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  1. ckpts/universal/global_step80/zero/12.attention.query_key_value.weight/exp_avg.pt +3 -0
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  6. venv/lib/python3.10/site-packages/sympy/integrals/__init__.py +43 -0
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  21. venv/lib/python3.10/site-packages/sympy/integrals/__pycache__/singularityfunctions.cpython-310.pyc +0 -0
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  23. venv/lib/python3.10/site-packages/sympy/integrals/__pycache__/trigonometry.cpython-310.pyc +0 -0
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  27. venv/lib/python3.10/site-packages/sympy/integrals/benchmarks/__pycache__/bench_trigintegrate.cpython-310.pyc +0 -0
  28. venv/lib/python3.10/site-packages/sympy/integrals/benchmarks/bench_integrate.py +21 -0
  29. venv/lib/python3.10/site-packages/sympy/integrals/benchmarks/bench_trigintegrate.py +13 -0
  30. venv/lib/python3.10/site-packages/sympy/integrals/deltafunctions.py +201 -0
  31. venv/lib/python3.10/site-packages/sympy/integrals/heurisch.py +771 -0
  32. venv/lib/python3.10/site-packages/sympy/integrals/integrals.py +1633 -0
  33. venv/lib/python3.10/site-packages/sympy/integrals/intpoly.py +1302 -0
  34. venv/lib/python3.10/site-packages/sympy/integrals/laplace.py +1761 -0
  35. venv/lib/python3.10/site-packages/sympy/integrals/manualintegrate.py +2171 -0
  36. venv/lib/python3.10/site-packages/sympy/integrals/meijerint.py +2190 -0
  37. venv/lib/python3.10/site-packages/sympy/integrals/meijerint_doc.py +37 -0
  38. venv/lib/python3.10/site-packages/sympy/integrals/prde.py +1332 -0
  39. venv/lib/python3.10/site-packages/sympy/integrals/quadrature.py +617 -0
  40. venv/lib/python3.10/site-packages/sympy/integrals/rationaltools.py +418 -0
  41. venv/lib/python3.10/site-packages/sympy/integrals/rde.py +800 -0
  42. venv/lib/python3.10/site-packages/sympy/integrals/risch.py +1858 -0
  43. venv/lib/python3.10/site-packages/sympy/integrals/singularityfunctions.py +63 -0
  44. venv/lib/python3.10/site-packages/sympy/integrals/tests/__init__.py +0 -0
  45. venv/lib/python3.10/site-packages/sympy/integrals/tests/__pycache__/test_heurisch.cpython-310.pyc +0 -0
  46. venv/lib/python3.10/site-packages/sympy/integrals/tests/__pycache__/test_integrals.cpython-310.pyc +0 -0
  47. venv/lib/python3.10/site-packages/sympy/integrals/tests/__pycache__/test_intpoly.cpython-310.pyc +0 -0
  48. venv/lib/python3.10/site-packages/sympy/integrals/tests/__pycache__/test_laplace.cpython-310.pyc +0 -0
  49. venv/lib/python3.10/site-packages/sympy/integrals/tests/__pycache__/test_risch.cpython-310.pyc +0 -0
  50. venv/lib/python3.10/site-packages/sympy/integrals/tests/__pycache__/test_transforms.cpython-310.pyc +0 -0
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@@ -0,0 +1,43 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """Integration functions that integrate a SymPy expression.
2
+
3
+ Examples
4
+ ========
5
+
6
+ >>> from sympy import integrate, sin
7
+ >>> from sympy.abc import x
8
+ >>> integrate(1/x,x)
9
+ log(x)
10
+ >>> integrate(sin(x),x)
11
+ -cos(x)
12
+ """
13
+ from .integrals import integrate, Integral, line_integrate
14
+ from .transforms import (mellin_transform, inverse_mellin_transform,
15
+ MellinTransform, InverseMellinTransform,
16
+ laplace_transform, inverse_laplace_transform,
17
+ LaplaceTransform, InverseLaplaceTransform,
18
+ fourier_transform, inverse_fourier_transform,
19
+ FourierTransform, InverseFourierTransform,
20
+ sine_transform, inverse_sine_transform,
21
+ SineTransform, InverseSineTransform,
22
+ cosine_transform, inverse_cosine_transform,
23
+ CosineTransform, InverseCosineTransform,
24
+ hankel_transform, inverse_hankel_transform,
25
+ HankelTransform, InverseHankelTransform)
26
+ from .singularityfunctions import singularityintegrate
27
+
28
+ __all__ = [
29
+ 'integrate', 'Integral', 'line_integrate',
30
+
31
+ 'mellin_transform', 'inverse_mellin_transform', 'MellinTransform',
32
+ 'InverseMellinTransform', 'laplace_transform',
33
+ 'inverse_laplace_transform', 'LaplaceTransform',
34
+ 'InverseLaplaceTransform', 'fourier_transform',
35
+ 'inverse_fourier_transform', 'FourierTransform',
36
+ 'InverseFourierTransform', 'sine_transform', 'inverse_sine_transform',
37
+ 'SineTransform', 'InverseSineTransform', 'cosine_transform',
38
+ 'inverse_cosine_transform', 'CosineTransform', 'InverseCosineTransform',
39
+ 'hankel_transform', 'inverse_hankel_transform', 'HankelTransform',
40
+ 'InverseHankelTransform',
41
+
42
+ 'singularityintegrate',
43
+ ]
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venv/lib/python3.10/site-packages/sympy/integrals/__pycache__/quadrature.cpython-310.pyc ADDED
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venv/lib/python3.10/site-packages/sympy/integrals/benchmarks/bench_integrate.py ADDED
@@ -0,0 +1,21 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ from sympy.core.symbol import Symbol
2
+ from sympy.functions.elementary.trigonometric import sin
3
+ from sympy.integrals.integrals import integrate
4
+
5
+ x = Symbol('x')
6
+
7
+
8
+ def bench_integrate_sin():
9
+ integrate(sin(x), x)
10
+
11
+
12
+ def bench_integrate_x1sin():
13
+ integrate(x**1*sin(x), x)
14
+
15
+
16
+ def bench_integrate_x2sin():
17
+ integrate(x**2*sin(x), x)
18
+
19
+
20
+ def bench_integrate_x3sin():
21
+ integrate(x**3*sin(x), x)
venv/lib/python3.10/site-packages/sympy/integrals/benchmarks/bench_trigintegrate.py ADDED
@@ -0,0 +1,13 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ from sympy.core.symbol import Symbol
2
+ from sympy.functions.elementary.trigonometric import sin
3
+ from sympy.integrals.trigonometry import trigintegrate
4
+
5
+ x = Symbol('x')
6
+
7
+
8
+ def timeit_trigintegrate_sin3x():
9
+ trigintegrate(sin(x)**3, x)
10
+
11
+
12
+ def timeit_trigintegrate_x2():
13
+ trigintegrate(x**2, x) # -> None
venv/lib/python3.10/site-packages/sympy/integrals/deltafunctions.py ADDED
@@ -0,0 +1,201 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ from sympy.core.mul import Mul
2
+ from sympy.core.singleton import S
3
+ from sympy.core.sorting import default_sort_key
4
+ from sympy.functions import DiracDelta, Heaviside
5
+ from .integrals import Integral, integrate
6
+
7
+
8
+ def change_mul(node, x):
9
+ """change_mul(node, x)
10
+
11
+ Rearranges the operands of a product, bringing to front any simple
12
+ DiracDelta expression.
13
+
14
+ Explanation
15
+ ===========
16
+
17
+ If no simple DiracDelta expression was found, then all the DiracDelta
18
+ expressions are simplified (using DiracDelta.expand(diracdelta=True, wrt=x)).
19
+
20
+ Return: (dirac, new node)
21
+ Where:
22
+ o dirac is either a simple DiracDelta expression or None (if no simple
23
+ expression was found);
24
+ o new node is either a simplified DiracDelta expressions or None (if it
25
+ could not be simplified).
26
+
27
+ Examples
28
+ ========
29
+
30
+ >>> from sympy import DiracDelta, cos
31
+ >>> from sympy.integrals.deltafunctions import change_mul
32
+ >>> from sympy.abc import x, y
33
+ >>> change_mul(x*y*DiracDelta(x)*cos(x), x)
34
+ (DiracDelta(x), x*y*cos(x))
35
+ >>> change_mul(x*y*DiracDelta(x**2 - 1)*cos(x), x)
36
+ (None, x*y*cos(x)*DiracDelta(x - 1)/2 + x*y*cos(x)*DiracDelta(x + 1)/2)
37
+ >>> change_mul(x*y*DiracDelta(cos(x))*cos(x), x)
38
+ (None, None)
39
+
40
+ See Also
41
+ ========
42
+
43
+ sympy.functions.special.delta_functions.DiracDelta
44
+ deltaintegrate
45
+ """
46
+
47
+ new_args = []
48
+ dirac = None
49
+
50
+ #Sorting is needed so that we consistently collapse the same delta;
51
+ #However, we must preserve the ordering of non-commutative terms
52
+ c, nc = node.args_cnc()
53
+ sorted_args = sorted(c, key=default_sort_key)
54
+ sorted_args.extend(nc)
55
+
56
+ for arg in sorted_args:
57
+ if arg.is_Pow and isinstance(arg.base, DiracDelta):
58
+ new_args.append(arg.func(arg.base, arg.exp - 1))
59
+ arg = arg.base
60
+ if dirac is None and (isinstance(arg, DiracDelta) and arg.is_simple(x)):
61
+ dirac = arg
62
+ else:
63
+ new_args.append(arg)
64
+ if not dirac: # there was no simple dirac
65
+ new_args = []
66
+ for arg in sorted_args:
67
+ if isinstance(arg, DiracDelta):
68
+ new_args.append(arg.expand(diracdelta=True, wrt=x))
69
+ elif arg.is_Pow and isinstance(arg.base, DiracDelta):
70
+ new_args.append(arg.func(arg.base.expand(diracdelta=True, wrt=x), arg.exp))
71
+ else:
72
+ new_args.append(arg)
73
+ if new_args != sorted_args:
74
+ nnode = Mul(*new_args).expand()
75
+ else: # if the node didn't change there is nothing to do
76
+ nnode = None
77
+ return (None, nnode)
78
+ return (dirac, Mul(*new_args))
79
+
80
+
81
+ def deltaintegrate(f, x):
82
+ """
83
+ deltaintegrate(f, x)
84
+
85
+ Explanation
86
+ ===========
87
+
88
+ The idea for integration is the following:
89
+
90
+ - If we are dealing with a DiracDelta expression, i.e. DiracDelta(g(x)),
91
+ we try to simplify it.
92
+
93
+ If we could simplify it, then we integrate the resulting expression.
94
+ We already know we can integrate a simplified expression, because only
95
+ simple DiracDelta expressions are involved.
96
+
97
+ If we couldn't simplify it, there are two cases:
98
+
99
+ 1) The expression is a simple expression: we return the integral,
100
+ taking care if we are dealing with a Derivative or with a proper
101
+ DiracDelta.
102
+
103
+ 2) The expression is not simple (i.e. DiracDelta(cos(x))): we can do
104
+ nothing at all.
105
+
106
+ - If the node is a multiplication node having a DiracDelta term:
107
+
108
+ First we expand it.
109
+
110
+ If the expansion did work, then we try to integrate the expansion.
111
+
112
+ If not, we try to extract a simple DiracDelta term, then we have two
113
+ cases:
114
+
115
+ 1) We have a simple DiracDelta term, so we return the integral.
116
+
117
+ 2) We didn't have a simple term, but we do have an expression with
118
+ simplified DiracDelta terms, so we integrate this expression.
119
+
120
+ Examples
121
+ ========
122
+
123
+ >>> from sympy.abc import x, y, z
124
+ >>> from sympy.integrals.deltafunctions import deltaintegrate
125
+ >>> from sympy import sin, cos, DiracDelta
126
+ >>> deltaintegrate(x*sin(x)*cos(x)*DiracDelta(x - 1), x)
127
+ sin(1)*cos(1)*Heaviside(x - 1)
128
+ >>> deltaintegrate(y**2*DiracDelta(x - z)*DiracDelta(y - z), y)
129
+ z**2*DiracDelta(x - z)*Heaviside(y - z)
130
+
131
+ See Also
132
+ ========
133
+
134
+ sympy.functions.special.delta_functions.DiracDelta
135
+ sympy.integrals.integrals.Integral
136
+ """
137
+ if not f.has(DiracDelta):
138
+ return None
139
+
140
+ # g(x) = DiracDelta(h(x))
141
+ if f.func == DiracDelta:
142
+ h = f.expand(diracdelta=True, wrt=x)
143
+ if h == f: # can't simplify the expression
144
+ #FIXME: the second term tells whether is DeltaDirac or Derivative
145
+ #For integrating derivatives of DiracDelta we need the chain rule
146
+ if f.is_simple(x):
147
+ if (len(f.args) <= 1 or f.args[1] == 0):
148
+ return Heaviside(f.args[0])
149
+ else:
150
+ return (DiracDelta(f.args[0], f.args[1] - 1) /
151
+ f.args[0].as_poly().LC())
152
+ else: # let's try to integrate the simplified expression
153
+ fh = integrate(h, x)
154
+ return fh
155
+ elif f.is_Mul or f.is_Pow: # g(x) = a*b*c*f(DiracDelta(h(x)))*d*e
156
+ g = f.expand()
157
+ if f != g: # the expansion worked
158
+ fh = integrate(g, x)
159
+ if fh is not None and not isinstance(fh, Integral):
160
+ return fh
161
+ else:
162
+ # no expansion performed, try to extract a simple DiracDelta term
163
+ deltaterm, rest_mult = change_mul(f, x)
164
+
165
+ if not deltaterm:
166
+ if rest_mult:
167
+ fh = integrate(rest_mult, x)
168
+ return fh
169
+ else:
170
+ from sympy.solvers import solve
171
+ deltaterm = deltaterm.expand(diracdelta=True, wrt=x)
172
+ if deltaterm.is_Mul: # Take out any extracted factors
173
+ deltaterm, rest_mult_2 = change_mul(deltaterm, x)
174
+ rest_mult = rest_mult*rest_mult_2
175
+ point = solve(deltaterm.args[0], x)[0]
176
+
177
+ # Return the largest hyperreal term left after
178
+ # repeated integration by parts. For example,
179
+ #
180
+ # integrate(y*DiracDelta(x, 1),x) == y*DiracDelta(x,0), not 0
181
+ #
182
+ # This is so Integral(y*DiracDelta(x).diff(x),x).doit()
183
+ # will return y*DiracDelta(x) instead of 0 or DiracDelta(x),
184
+ # both of which are correct everywhere the value is defined
185
+ # but give wrong answers for nested integration.
186
+ n = (0 if len(deltaterm.args)==1 else deltaterm.args[1])
187
+ m = 0
188
+ while n >= 0:
189
+ r = S.NegativeOne**n*rest_mult.diff(x, n).subs(x, point)
190
+ if r.is_zero:
191
+ n -= 1
192
+ m += 1
193
+ else:
194
+ if m == 0:
195
+ return r*Heaviside(x - point)
196
+ else:
197
+ return r*DiracDelta(x,m-1)
198
+ # In some very weak sense, x=0 is still a singularity,
199
+ # but we hope will not be of any practical consequence.
200
+ return S.Zero
201
+ return None
venv/lib/python3.10/site-packages/sympy/integrals/heurisch.py ADDED
@@ -0,0 +1,771 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ from __future__ import annotations
2
+
3
+ from itertools import permutations
4
+ from functools import reduce
5
+
6
+ from sympy.core.add import Add
7
+ from sympy.core.basic import Basic
8
+ from sympy.core.mul import Mul
9
+ from sympy.core.symbol import Wild, Dummy, Symbol
10
+ from sympy.core.basic import sympify
11
+ from sympy.core.numbers import Rational, pi, I
12
+ from sympy.core.relational import Eq, Ne
13
+ from sympy.core.singleton import S
14
+ from sympy.core.sorting import ordered
15
+ from sympy.core.traversal import iterfreeargs
16
+
17
+ from sympy.functions import exp, sin, cos, tan, cot, asin, atan
18
+ from sympy.functions import log, sinh, cosh, tanh, coth, asinh
19
+ from sympy.functions import sqrt, erf, erfi, li, Ei
20
+ from sympy.functions import besselj, bessely, besseli, besselk
21
+ from sympy.functions import hankel1, hankel2, jn, yn
22
+ from sympy.functions.elementary.complexes import Abs, re, im, sign, arg
23
+ from sympy.functions.elementary.exponential import LambertW
24
+ from sympy.functions.elementary.integers import floor, ceiling
25
+ from sympy.functions.elementary.piecewise import Piecewise
26
+ from sympy.functions.special.delta_functions import Heaviside, DiracDelta
27
+
28
+ from sympy.simplify.radsimp import collect
29
+
30
+ from sympy.logic.boolalg import And, Or
31
+ from sympy.utilities.iterables import uniq
32
+
33
+ from sympy.polys import quo, gcd, lcm, factor_list, cancel, PolynomialError
34
+ from sympy.polys.monomials import itermonomials
35
+ from sympy.polys.polyroots import root_factors
36
+
37
+ from sympy.polys.rings import PolyRing
38
+ from sympy.polys.solvers import solve_lin_sys
39
+ from sympy.polys.constructor import construct_domain
40
+
41
+ from sympy.integrals.integrals import integrate
42
+
43
+
44
+ def components(f, x):
45
+ """
46
+ Returns a set of all functional components of the given expression
47
+ which includes symbols, function applications and compositions and
48
+ non-integer powers. Fractional powers are collected with
49
+ minimal, positive exponents.
50
+
51
+ Examples
52
+ ========
53
+
54
+ >>> from sympy import cos, sin
55
+ >>> from sympy.abc import x
56
+ >>> from sympy.integrals.heurisch import components
57
+
58
+ >>> components(sin(x)*cos(x)**2, x)
59
+ {x, sin(x), cos(x)}
60
+
61
+ See Also
62
+ ========
63
+
64
+ heurisch
65
+ """
66
+ result = set()
67
+
68
+ if f.has_free(x):
69
+ if f.is_symbol and f.is_commutative:
70
+ result.add(f)
71
+ elif f.is_Function or f.is_Derivative:
72
+ for g in f.args:
73
+ result |= components(g, x)
74
+
75
+ result.add(f)
76
+ elif f.is_Pow:
77
+ result |= components(f.base, x)
78
+
79
+ if not f.exp.is_Integer:
80
+ if f.exp.is_Rational:
81
+ result.add(f.base**Rational(1, f.exp.q))
82
+ else:
83
+ result |= components(f.exp, x) | {f}
84
+ else:
85
+ for g in f.args:
86
+ result |= components(g, x)
87
+
88
+ return result
89
+
90
+ # name -> [] of symbols
91
+ _symbols_cache: dict[str, list[Dummy]] = {}
92
+
93
+
94
+ # NB @cacheit is not convenient here
95
+ def _symbols(name, n):
96
+ """get vector of symbols local to this module"""
97
+ try:
98
+ lsyms = _symbols_cache[name]
99
+ except KeyError:
100
+ lsyms = []
101
+ _symbols_cache[name] = lsyms
102
+
103
+ while len(lsyms) < n:
104
+ lsyms.append( Dummy('%s%i' % (name, len(lsyms))) )
105
+
106
+ return lsyms[:n]
107
+
108
+
109
+ def heurisch_wrapper(f, x, rewrite=False, hints=None, mappings=None, retries=3,
110
+ degree_offset=0, unnecessary_permutations=None,
111
+ _try_heurisch=None):
112
+ """
113
+ A wrapper around the heurisch integration algorithm.
114
+
115
+ Explanation
116
+ ===========
117
+
118
+ This method takes the result from heurisch and checks for poles in the
119
+ denominator. For each of these poles, the integral is reevaluated, and
120
+ the final integration result is given in terms of a Piecewise.
121
+
122
+ Examples
123
+ ========
124
+
125
+ >>> from sympy import cos, symbols
126
+ >>> from sympy.integrals.heurisch import heurisch, heurisch_wrapper
127
+ >>> n, x = symbols('n x')
128
+ >>> heurisch(cos(n*x), x)
129
+ sin(n*x)/n
130
+ >>> heurisch_wrapper(cos(n*x), x)
131
+ Piecewise((sin(n*x)/n, Ne(n, 0)), (x, True))
132
+
133
+ See Also
134
+ ========
135
+
136
+ heurisch
137
+ """
138
+ from sympy.solvers.solvers import solve, denoms
139
+ f = sympify(f)
140
+ if not f.has_free(x):
141
+ return f*x
142
+
143
+ res = heurisch(f, x, rewrite, hints, mappings, retries, degree_offset,
144
+ unnecessary_permutations, _try_heurisch)
145
+ if not isinstance(res, Basic):
146
+ return res
147
+
148
+ # We consider each denominator in the expression, and try to find
149
+ # cases where one or more symbolic denominator might be zero. The
150
+ # conditions for these cases are stored in the list slns.
151
+ #
152
+ # Since denoms returns a set we use ordered. This is important because the
153
+ # ordering of slns determines the order of the resulting Piecewise so we
154
+ # need a deterministic order here to make the output deterministic.
155
+ slns = []
156
+ for d in ordered(denoms(res)):
157
+ try:
158
+ slns += solve([d], dict=True, exclude=(x,))
159
+ except NotImplementedError:
160
+ pass
161
+ if not slns:
162
+ return res
163
+ slns = list(uniq(slns))
164
+ # Remove the solutions corresponding to poles in the original expression.
165
+ slns0 = []
166
+ for d in denoms(f):
167
+ try:
168
+ slns0 += solve([d], dict=True, exclude=(x,))
169
+ except NotImplementedError:
170
+ pass
171
+ slns = [s for s in slns if s not in slns0]
172
+ if not slns:
173
+ return res
174
+ if len(slns) > 1:
175
+ eqs = []
176
+ for sub_dict in slns:
177
+ eqs.extend([Eq(key, value) for key, value in sub_dict.items()])
178
+ slns = solve(eqs, dict=True, exclude=(x,)) + slns
179
+ # For each case listed in the list slns, we reevaluate the integral.
180
+ pairs = []
181
+ for sub_dict in slns:
182
+ expr = heurisch(f.subs(sub_dict), x, rewrite, hints, mappings, retries,
183
+ degree_offset, unnecessary_permutations,
184
+ _try_heurisch)
185
+ cond = And(*[Eq(key, value) for key, value in sub_dict.items()])
186
+ generic = Or(*[Ne(key, value) for key, value in sub_dict.items()])
187
+ if expr is None:
188
+ expr = integrate(f.subs(sub_dict),x)
189
+ pairs.append((expr, cond))
190
+ # If there is one condition, put the generic case first. Otherwise,
191
+ # doing so may lead to longer Piecewise formulas
192
+ if len(pairs) == 1:
193
+ pairs = [(heurisch(f, x, rewrite, hints, mappings, retries,
194
+ degree_offset, unnecessary_permutations,
195
+ _try_heurisch),
196
+ generic),
197
+ (pairs[0][0], True)]
198
+ else:
199
+ pairs.append((heurisch(f, x, rewrite, hints, mappings, retries,
200
+ degree_offset, unnecessary_permutations,
201
+ _try_heurisch),
202
+ True))
203
+ return Piecewise(*pairs)
204
+
205
+ class BesselTable:
206
+ """
207
+ Derivatives of Bessel functions of orders n and n-1
208
+ in terms of each other.
209
+
210
+ See the docstring of DiffCache.
211
+ """
212
+
213
+ def __init__(self):
214
+ self.table = {}
215
+ self.n = Dummy('n')
216
+ self.z = Dummy('z')
217
+ self._create_table()
218
+
219
+ def _create_table(t):
220
+ table, n, z = t.table, t.n, t.z
221
+ for f in (besselj, bessely, hankel1, hankel2):
222
+ table[f] = (f(n-1, z) - n*f(n, z)/z,
223
+ (n-1)*f(n-1, z)/z - f(n, z))
224
+
225
+ f = besseli
226
+ table[f] = (f(n-1, z) - n*f(n, z)/z,
227
+ (n-1)*f(n-1, z)/z + f(n, z))
228
+ f = besselk
229
+ table[f] = (-f(n-1, z) - n*f(n, z)/z,
230
+ (n-1)*f(n-1, z)/z - f(n, z))
231
+
232
+ for f in (jn, yn):
233
+ table[f] = (f(n-1, z) - (n+1)*f(n, z)/z,
234
+ (n-1)*f(n-1, z)/z - f(n, z))
235
+
236
+ def diffs(t, f, n, z):
237
+ if f in t.table:
238
+ diff0, diff1 = t.table[f]
239
+ repl = [(t.n, n), (t.z, z)]
240
+ return (diff0.subs(repl), diff1.subs(repl))
241
+
242
+ def has(t, f):
243
+ return f in t.table
244
+
245
+ _bessel_table = None
246
+
247
+ class DiffCache:
248
+ """
249
+ Store for derivatives of expressions.
250
+
251
+ Explanation
252
+ ===========
253
+
254
+ The standard form of the derivative of a Bessel function of order n
255
+ contains two Bessel functions of orders n-1 and n+1, respectively.
256
+ Such forms cannot be used in parallel Risch algorithm, because
257
+ there is a linear recurrence relation between the three functions
258
+ while the algorithm expects that functions and derivatives are
259
+ represented in terms of algebraically independent transcendentals.
260
+
261
+ The solution is to take two of the functions, e.g., those of orders
262
+ n and n-1, and to express the derivatives in terms of the pair.
263
+ To guarantee that the proper form is used the two derivatives are
264
+ cached as soon as one is encountered.
265
+
266
+ Derivatives of other functions are also cached at no extra cost.
267
+ All derivatives are with respect to the same variable `x`.
268
+ """
269
+
270
+ def __init__(self, x):
271
+ self.cache = {}
272
+ self.x = x
273
+
274
+ global _bessel_table
275
+ if not _bessel_table:
276
+ _bessel_table = BesselTable()
277
+
278
+ def get_diff(self, f):
279
+ cache = self.cache
280
+
281
+ if f in cache:
282
+ pass
283
+ elif (not hasattr(f, 'func') or
284
+ not _bessel_table.has(f.func)):
285
+ cache[f] = cancel(f.diff(self.x))
286
+ else:
287
+ n, z = f.args
288
+ d0, d1 = _bessel_table.diffs(f.func, n, z)
289
+ dz = self.get_diff(z)
290
+ cache[f] = d0*dz
291
+ cache[f.func(n-1, z)] = d1*dz
292
+
293
+ return cache[f]
294
+
295
+ def heurisch(f, x, rewrite=False, hints=None, mappings=None, retries=3,
296
+ degree_offset=0, unnecessary_permutations=None,
297
+ _try_heurisch=None):
298
+ """
299
+ Compute indefinite integral using heuristic Risch algorithm.
300
+
301
+ Explanation
302
+ ===========
303
+
304
+ This is a heuristic approach to indefinite integration in finite
305
+ terms using the extended heuristic (parallel) Risch algorithm, based
306
+ on Manuel Bronstein's "Poor Man's Integrator".
307
+
308
+ The algorithm supports various classes of functions including
309
+ transcendental elementary or special functions like Airy,
310
+ Bessel, Whittaker and Lambert.
311
+
312
+ Note that this algorithm is not a decision procedure. If it isn't
313
+ able to compute the antiderivative for a given function, then this is
314
+ not a proof that such a functions does not exist. One should use
315
+ recursive Risch algorithm in such case. It's an open question if
316
+ this algorithm can be made a full decision procedure.
317
+
318
+ This is an internal integrator procedure. You should use top level
319
+ 'integrate' function in most cases, as this procedure needs some
320
+ preprocessing steps and otherwise may fail.
321
+
322
+ Specification
323
+ =============
324
+
325
+ heurisch(f, x, rewrite=False, hints=None)
326
+
327
+ where
328
+ f : expression
329
+ x : symbol
330
+
331
+ rewrite -> force rewrite 'f' in terms of 'tan' and 'tanh'
332
+ hints -> a list of functions that may appear in anti-derivate
333
+
334
+ - hints = None --> no suggestions at all
335
+ - hints = [ ] --> try to figure out
336
+ - hints = [f1, ..., fn] --> we know better
337
+
338
+ Examples
339
+ ========
340
+
341
+ >>> from sympy import tan
342
+ >>> from sympy.integrals.heurisch import heurisch
343
+ >>> from sympy.abc import x, y
344
+
345
+ >>> heurisch(y*tan(x), x)
346
+ y*log(tan(x)**2 + 1)/2
347
+
348
+ See Manuel Bronstein's "Poor Man's Integrator":
349
+
350
+ References
351
+ ==========
352
+
353
+ .. [1] https://www-sop.inria.fr/cafe/Manuel.Bronstein/pmint/index.html
354
+
355
+ For more information on the implemented algorithm refer to:
356
+
357
+ .. [2] K. Geddes, L. Stefanus, On the Risch-Norman Integration
358
+ Method and its Implementation in Maple, Proceedings of
359
+ ISSAC'89, ACM Press, 212-217.
360
+
361
+ .. [3] J. H. Davenport, On the Parallel Risch Algorithm (I),
362
+ Proceedings of EUROCAM'82, LNCS 144, Springer, 144-157.
363
+
364
+ .. [4] J. H. Davenport, On the Parallel Risch Algorithm (III):
365
+ Use of Tangents, SIGSAM Bulletin 16 (1982), 3-6.
366
+
367
+ .. [5] J. H. Davenport, B. M. Trager, On the Parallel Risch
368
+ Algorithm (II), ACM Transactions on Mathematical
369
+ Software 11 (1985), 356-362.
370
+
371
+ See Also
372
+ ========
373
+
374
+ sympy.integrals.integrals.Integral.doit
375
+ sympy.integrals.integrals.Integral
376
+ sympy.integrals.heurisch.components
377
+ """
378
+ f = sympify(f)
379
+
380
+ # There are some functions that Heurisch cannot currently handle,
381
+ # so do not even try.
382
+ # Set _try_heurisch=True to skip this check
383
+ if _try_heurisch is not True:
384
+ if f.has(Abs, re, im, sign, Heaviside, DiracDelta, floor, ceiling, arg):
385
+ return
386
+
387
+ if not f.has_free(x):
388
+ return f*x
389
+
390
+ if not f.is_Add:
391
+ indep, f = f.as_independent(x)
392
+ else:
393
+ indep = S.One
394
+
395
+ rewritables = {
396
+ (sin, cos, cot): tan,
397
+ (sinh, cosh, coth): tanh,
398
+ }
399
+
400
+ if rewrite:
401
+ for candidates, rule in rewritables.items():
402
+ f = f.rewrite(candidates, rule)
403
+ else:
404
+ for candidates in rewritables.keys():
405
+ if f.has(*candidates):
406
+ break
407
+ else:
408
+ rewrite = True
409
+
410
+ terms = components(f, x)
411
+ dcache = DiffCache(x)
412
+
413
+ if hints is not None:
414
+ if not hints:
415
+ a = Wild('a', exclude=[x])
416
+ b = Wild('b', exclude=[x])
417
+ c = Wild('c', exclude=[x])
418
+
419
+ for g in set(terms): # using copy of terms
420
+ if g.is_Function:
421
+ if isinstance(g, li):
422
+ M = g.args[0].match(a*x**b)
423
+
424
+ if M is not None:
425
+ terms.add( x*(li(M[a]*x**M[b]) - (M[a]*x**M[b])**(-1/M[b])*Ei((M[b]+1)*log(M[a]*x**M[b])/M[b])) )
426
+ #terms.add( x*(li(M[a]*x**M[b]) - (x**M[b])**(-1/M[b])*Ei((M[b]+1)*log(M[a]*x**M[b])/M[b])) )
427
+ #terms.add( x*(li(M[a]*x**M[b]) - x*Ei((M[b]+1)*log(M[a]*x**M[b])/M[b])) )
428
+ #terms.add( li(M[a]*x**M[b]) - Ei((M[b]+1)*log(M[a]*x**M[b])/M[b]) )
429
+
430
+ elif isinstance(g, exp):
431
+ M = g.args[0].match(a*x**2)
432
+
433
+ if M is not None:
434
+ if M[a].is_positive:
435
+ terms.add(erfi(sqrt(M[a])*x))
436
+ else: # M[a].is_negative or unknown
437
+ terms.add(erf(sqrt(-M[a])*x))
438
+
439
+ M = g.args[0].match(a*x**2 + b*x + c)
440
+
441
+ if M is not None:
442
+ if M[a].is_positive:
443
+ terms.add(sqrt(pi/4*(-M[a]))*exp(M[c] - M[b]**2/(4*M[a]))*
444
+ erfi(sqrt(M[a])*x + M[b]/(2*sqrt(M[a]))))
445
+ elif M[a].is_negative:
446
+ terms.add(sqrt(pi/4*(-M[a]))*exp(M[c] - M[b]**2/(4*M[a]))*
447
+ erf(sqrt(-M[a])*x - M[b]/(2*sqrt(-M[a]))))
448
+
449
+ M = g.args[0].match(a*log(x)**2)
450
+
451
+ if M is not None:
452
+ if M[a].is_positive:
453
+ terms.add(erfi(sqrt(M[a])*log(x) + 1/(2*sqrt(M[a]))))
454
+ if M[a].is_negative:
455
+ terms.add(erf(sqrt(-M[a])*log(x) - 1/(2*sqrt(-M[a]))))
456
+
457
+ elif g.is_Pow:
458
+ if g.exp.is_Rational and g.exp.q == 2:
459
+ M = g.base.match(a*x**2 + b)
460
+
461
+ if M is not None and M[b].is_positive:
462
+ if M[a].is_positive:
463
+ terms.add(asinh(sqrt(M[a]/M[b])*x))
464
+ elif M[a].is_negative:
465
+ terms.add(asin(sqrt(-M[a]/M[b])*x))
466
+
467
+ M = g.base.match(a*x**2 - b)
468
+
469
+ if M is not None and M[b].is_positive:
470
+ if M[a].is_positive:
471
+ dF = 1/sqrt(M[a]*x**2 - M[b])
472
+ F = log(2*sqrt(M[a])*sqrt(M[a]*x**2 - M[b]) + 2*M[a]*x)/sqrt(M[a])
473
+ dcache.cache[F] = dF # hack: F.diff(x) doesn't automatically simplify to f
474
+ terms.add(F)
475
+ elif M[a].is_negative:
476
+ terms.add(-M[b]/2*sqrt(-M[a])*
477
+ atan(sqrt(-M[a])*x/sqrt(M[a]*x**2 - M[b])))
478
+
479
+ else:
480
+ terms |= set(hints)
481
+
482
+ for g in set(terms): # using copy of terms
483
+ terms |= components(dcache.get_diff(g), x)
484
+
485
+ # XXX: The commented line below makes heurisch more deterministic wrt
486
+ # PYTHONHASHSEED and the iteration order of sets. There are other places
487
+ # where sets are iterated over but this one is possibly the most important.
488
+ # Theoretically the order here should not matter but different orderings
489
+ # can expose potential bugs in the different code paths so potentially it
490
+ # is better to keep the non-determinism.
491
+ #
492
+ # terms = list(ordered(terms))
493
+
494
+ # TODO: caching is significant factor for why permutations work at all. Change this.
495
+ V = _symbols('x', len(terms))
496
+
497
+
498
+ # sort mapping expressions from largest to smallest (last is always x).
499
+ mapping = list(reversed(list(zip(*ordered( #
500
+ [(a[0].as_independent(x)[1], a) for a in zip(terms, V)])))[1])) #
501
+ rev_mapping = {v: k for k, v in mapping} #
502
+ if mappings is None: #
503
+ # optimizing the number of permutations of mapping #
504
+ assert mapping[-1][0] == x # if not, find it and correct this comment
505
+ unnecessary_permutations = [mapping.pop(-1)]
506
+ mappings = permutations(mapping)
507
+ else:
508
+ unnecessary_permutations = unnecessary_permutations or []
509
+
510
+ def _substitute(expr):
511
+ return expr.subs(mapping)
512
+
513
+ for mapping in mappings:
514
+ mapping = list(mapping)
515
+ mapping = mapping + unnecessary_permutations
516
+ diffs = [ _substitute(dcache.get_diff(g)) for g in terms ]
517
+ denoms = [ g.as_numer_denom()[1] for g in diffs ]
518
+ if all(h.is_polynomial(*V) for h in denoms) and _substitute(f).is_rational_function(*V):
519
+ denom = reduce(lambda p, q: lcm(p, q, *V), denoms)
520
+ break
521
+ else:
522
+ if not rewrite:
523
+ result = heurisch(f, x, rewrite=True, hints=hints,
524
+ unnecessary_permutations=unnecessary_permutations)
525
+
526
+ if result is not None:
527
+ return indep*result
528
+ return None
529
+
530
+ numers = [ cancel(denom*g) for g in diffs ]
531
+ def _derivation(h):
532
+ return Add(*[ d * h.diff(v) for d, v in zip(numers, V) ])
533
+
534
+ def _deflation(p):
535
+ for y in V:
536
+ if not p.has(y):
537
+ continue
538
+
539
+ if _derivation(p) is not S.Zero:
540
+ c, q = p.as_poly(y).primitive()
541
+ return _deflation(c)*gcd(q, q.diff(y)).as_expr()
542
+
543
+ return p
544
+
545
+ def _splitter(p):
546
+ for y in V:
547
+ if not p.has(y):
548
+ continue
549
+
550
+ if _derivation(y) is not S.Zero:
551
+ c, q = p.as_poly(y).primitive()
552
+
553
+ q = q.as_expr()
554
+
555
+ h = gcd(q, _derivation(q), y)
556
+ s = quo(h, gcd(q, q.diff(y), y), y)
557
+
558
+ c_split = _splitter(c)
559
+
560
+ if s.as_poly(y).degree() == 0:
561
+ return (c_split[0], q * c_split[1])
562
+
563
+ q_split = _splitter(cancel(q / s))
564
+
565
+ return (c_split[0]*q_split[0]*s, c_split[1]*q_split[1])
566
+
567
+ return (S.One, p)
568
+
569
+ special = {}
570
+
571
+ for term in terms:
572
+ if term.is_Function:
573
+ if isinstance(term, tan):
574
+ special[1 + _substitute(term)**2] = False
575
+ elif isinstance(term, tanh):
576
+ special[1 + _substitute(term)] = False
577
+ special[1 - _substitute(term)] = False
578
+ elif isinstance(term, LambertW):
579
+ special[_substitute(term)] = True
580
+
581
+ F = _substitute(f)
582
+
583
+ P, Q = F.as_numer_denom()
584
+
585
+ u_split = _splitter(denom)
586
+ v_split = _splitter(Q)
587
+
588
+ polys = set(list(v_split) + [ u_split[0] ] + list(special.keys()))
589
+
590
+ s = u_split[0] * Mul(*[ k for k, v in special.items() if v ])
591
+ polified = [ p.as_poly(*V) for p in [s, P, Q] ]
592
+
593
+ if None in polified:
594
+ return None
595
+
596
+ #--- definitions for _integrate
597
+ a, b, c = [ p.total_degree() for p in polified ]
598
+
599
+ poly_denom = (s * v_split[0] * _deflation(v_split[1])).as_expr()
600
+
601
+ def _exponent(g):
602
+ if g.is_Pow:
603
+ if g.exp.is_Rational and g.exp.q != 1:
604
+ if g.exp.p > 0:
605
+ return g.exp.p + g.exp.q - 1
606
+ else:
607
+ return abs(g.exp.p + g.exp.q)
608
+ else:
609
+ return 1
610
+ elif not g.is_Atom and g.args:
611
+ return max([ _exponent(h) for h in g.args ])
612
+ else:
613
+ return 1
614
+
615
+ A, B = _exponent(f), a + max(b, c)
616
+
617
+ if A > 1 and B > 1:
618
+ monoms = tuple(ordered(itermonomials(V, A + B - 1 + degree_offset)))
619
+ else:
620
+ monoms = tuple(ordered(itermonomials(V, A + B + degree_offset)))
621
+
622
+ poly_coeffs = _symbols('A', len(monoms))
623
+
624
+ poly_part = Add(*[ poly_coeffs[i]*monomial
625
+ for i, monomial in enumerate(monoms) ])
626
+
627
+ reducibles = set()
628
+
629
+ for poly in ordered(polys):
630
+ coeff, factors = factor_list(poly, *V)
631
+ reducibles.add(coeff)
632
+ for fact, mul in factors:
633
+ reducibles.add(fact)
634
+
635
+ def _integrate(field=None):
636
+ atans = set()
637
+ pairs = set()
638
+
639
+ if field == 'Q':
640
+ irreducibles = set(reducibles)
641
+ else:
642
+ setV = set(V)
643
+ irreducibles = set()
644
+ for poly in ordered(reducibles):
645
+ zV = setV & set(iterfreeargs(poly))
646
+ for z in ordered(zV):
647
+ s = set(root_factors(poly, z, filter=field))
648
+ irreducibles |= s
649
+ break
650
+
651
+ log_part, atan_part = [], []
652
+
653
+ for poly in ordered(irreducibles):
654
+ m = collect(poly, I, evaluate=False)
655
+ y = m.get(I, S.Zero)
656
+ if y:
657
+ x = m.get(S.One, S.Zero)
658
+ if x.has(I) or y.has(I):
659
+ continue # nontrivial x + I*y
660
+ pairs.add((x, y))
661
+ irreducibles.remove(poly)
662
+
663
+ while pairs:
664
+ x, y = pairs.pop()
665
+ if (x, -y) in pairs:
666
+ pairs.remove((x, -y))
667
+ # Choosing b with no minus sign
668
+ if y.could_extract_minus_sign():
669
+ y = -y
670
+ irreducibles.add(x*x + y*y)
671
+ atans.add(atan(x/y))
672
+ else:
673
+ irreducibles.add(x + I*y)
674
+
675
+
676
+ B = _symbols('B', len(irreducibles))
677
+ C = _symbols('C', len(atans))
678
+
679
+ # Note: the ordering matters here
680
+ for poly, b in reversed(list(zip(ordered(irreducibles), B))):
681
+ if poly.has(*V):
682
+ poly_coeffs.append(b)
683
+ log_part.append(b * log(poly))
684
+
685
+ for poly, c in reversed(list(zip(ordered(atans), C))):
686
+ if poly.has(*V):
687
+ poly_coeffs.append(c)
688
+ atan_part.append(c * poly)
689
+
690
+ # TODO: Currently it's better to use symbolic expressions here instead
691
+ # of rational functions, because it's simpler and FracElement doesn't
692
+ # give big speed improvement yet. This is because cancellation is slow
693
+ # due to slow polynomial GCD algorithms. If this gets improved then
694
+ # revise this code.
695
+ candidate = poly_part/poly_denom + Add(*log_part) + Add(*atan_part)
696
+ h = F - _derivation(candidate) / denom
697
+ raw_numer = h.as_numer_denom()[0]
698
+
699
+ # Rewrite raw_numer as a polynomial in K[coeffs][V] where K is a field
700
+ # that we have to determine. We can't use simply atoms() because log(3),
701
+ # sqrt(y) and similar expressions can appear, leading to non-trivial
702
+ # domains.
703
+ syms = set(poly_coeffs) | set(V)
704
+ non_syms = set()
705
+
706
+ def find_non_syms(expr):
707
+ if expr.is_Integer or expr.is_Rational:
708
+ pass # ignore trivial numbers
709
+ elif expr in syms:
710
+ pass # ignore variables
711
+ elif not expr.has_free(*syms):
712
+ non_syms.add(expr)
713
+ elif expr.is_Add or expr.is_Mul or expr.is_Pow:
714
+ list(map(find_non_syms, expr.args))
715
+ else:
716
+ # TODO: Non-polynomial expression. This should have been
717
+ # filtered out at an earlier stage.
718
+ raise PolynomialError
719
+
720
+ try:
721
+ find_non_syms(raw_numer)
722
+ except PolynomialError:
723
+ return None
724
+ else:
725
+ ground, _ = construct_domain(non_syms, field=True)
726
+
727
+ coeff_ring = PolyRing(poly_coeffs, ground)
728
+ ring = PolyRing(V, coeff_ring)
729
+ try:
730
+ numer = ring.from_expr(raw_numer)
731
+ except ValueError:
732
+ raise PolynomialError
733
+ solution = solve_lin_sys(numer.coeffs(), coeff_ring, _raw=False)
734
+
735
+ if solution is None:
736
+ return None
737
+ else:
738
+ return candidate.xreplace(solution).xreplace(
739
+ dict(zip(poly_coeffs, [S.Zero]*len(poly_coeffs))))
740
+
741
+ if all(isinstance(_, Symbol) for _ in V):
742
+ more_free = F.free_symbols - set(V)
743
+ else:
744
+ Fd = F.as_dummy()
745
+ more_free = Fd.xreplace(dict(zip(V, (Dummy() for _ in V)))
746
+ ).free_symbols & Fd.free_symbols
747
+ if not more_free:
748
+ # all free generators are identified in V
749
+ solution = _integrate('Q')
750
+
751
+ if solution is None:
752
+ solution = _integrate()
753
+ else:
754
+ solution = _integrate()
755
+
756
+ if solution is not None:
757
+ antideriv = solution.subs(rev_mapping)
758
+ antideriv = cancel(antideriv).expand()
759
+
760
+ if antideriv.is_Add:
761
+ antideriv = antideriv.as_independent(x)[1]
762
+
763
+ return indep*antideriv
764
+ else:
765
+ if retries >= 0:
766
+ result = heurisch(f, x, mappings=mappings, rewrite=rewrite, hints=hints, retries=retries - 1, unnecessary_permutations=unnecessary_permutations)
767
+
768
+ if result is not None:
769
+ return indep*result
770
+
771
+ return None
venv/lib/python3.10/site-packages/sympy/integrals/integrals.py ADDED
@@ -0,0 +1,1633 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ from typing import Tuple as tTuple
2
+
3
+ from sympy.concrete.expr_with_limits import AddWithLimits
4
+ from sympy.core.add import Add
5
+ from sympy.core.basic import Basic
6
+ from sympy.core.containers import Tuple
7
+ from sympy.core.expr import Expr
8
+ from sympy.core.exprtools import factor_terms
9
+ from sympy.core.function import diff
10
+ from sympy.core.logic import fuzzy_bool
11
+ from sympy.core.mul import Mul
12
+ from sympy.core.numbers import oo, pi
13
+ from sympy.core.relational import Ne
14
+ from sympy.core.singleton import S
15
+ from sympy.core.symbol import (Dummy, Symbol, Wild)
16
+ from sympy.core.sympify import sympify
17
+ from sympy.functions import Piecewise, sqrt, piecewise_fold, tan, cot, atan
18
+ from sympy.functions.elementary.exponential import log
19
+ from sympy.functions.elementary.integers import floor
20
+ from sympy.functions.elementary.complexes import Abs, sign
21
+ from sympy.functions.elementary.miscellaneous import Min, Max
22
+ from .rationaltools import ratint
23
+ from sympy.matrices import MatrixBase
24
+ from sympy.polys import Poly, PolynomialError
25
+ from sympy.series.formal import FormalPowerSeries
26
+ from sympy.series.limits import limit
27
+ from sympy.series.order import Order
28
+ from sympy.tensor.functions import shape
29
+ from sympy.utilities.exceptions import sympy_deprecation_warning
30
+ from sympy.utilities.iterables import is_sequence
31
+ from sympy.utilities.misc import filldedent
32
+
33
+
34
+ class Integral(AddWithLimits):
35
+ """Represents unevaluated integral."""
36
+
37
+ __slots__ = ()
38
+
39
+ args: tTuple[Expr, Tuple]
40
+
41
+ def __new__(cls, function, *symbols, **assumptions):
42
+ """Create an unevaluated integral.
43
+
44
+ Explanation
45
+ ===========
46
+
47
+ Arguments are an integrand followed by one or more limits.
48
+
49
+ If no limits are given and there is only one free symbol in the
50
+ expression, that symbol will be used, otherwise an error will be
51
+ raised.
52
+
53
+ >>> from sympy import Integral
54
+ >>> from sympy.abc import x, y
55
+ >>> Integral(x)
56
+ Integral(x, x)
57
+ >>> Integral(y)
58
+ Integral(y, y)
59
+
60
+ When limits are provided, they are interpreted as follows (using
61
+ ``x`` as though it were the variable of integration):
62
+
63
+ (x,) or x - indefinite integral
64
+ (x, a) - "evaluate at" integral is an abstract antiderivative
65
+ (x, a, b) - definite integral
66
+
67
+ The ``as_dummy`` method can be used to see which symbols cannot be
68
+ targeted by subs: those with a prepended underscore cannot be
69
+ changed with ``subs``. (Also, the integration variables themselves --
70
+ the first element of a limit -- can never be changed by subs.)
71
+
72
+ >>> i = Integral(x, x)
73
+ >>> at = Integral(x, (x, x))
74
+ >>> i.as_dummy()
75
+ Integral(x, x)
76
+ >>> at.as_dummy()
77
+ Integral(_0, (_0, x))
78
+
79
+ """
80
+
81
+ #This will help other classes define their own definitions
82
+ #of behaviour with Integral.
83
+ if hasattr(function, '_eval_Integral'):
84
+ return function._eval_Integral(*symbols, **assumptions)
85
+
86
+ if isinstance(function, Poly):
87
+ sympy_deprecation_warning(
88
+ """
89
+ integrate(Poly) and Integral(Poly) are deprecated. Instead,
90
+ use the Poly.integrate() method, or convert the Poly to an
91
+ Expr first with the Poly.as_expr() method.
92
+ """,
93
+ deprecated_since_version="1.6",
94
+ active_deprecations_target="deprecated-integrate-poly")
95
+
96
+ obj = AddWithLimits.__new__(cls, function, *symbols, **assumptions)
97
+ return obj
98
+
99
+ def __getnewargs__(self):
100
+ return (self.function,) + tuple([tuple(xab) for xab in self.limits])
101
+
102
+ @property
103
+ def free_symbols(self):
104
+ """
105
+ This method returns the symbols that will exist when the
106
+ integral is evaluated. This is useful if one is trying to
107
+ determine whether an integral depends on a certain
108
+ symbol or not.
109
+
110
+ Examples
111
+ ========
112
+
113
+ >>> from sympy import Integral
114
+ >>> from sympy.abc import x, y
115
+ >>> Integral(x, (x, y, 1)).free_symbols
116
+ {y}
117
+
118
+ See Also
119
+ ========
120
+
121
+ sympy.concrete.expr_with_limits.ExprWithLimits.function
122
+ sympy.concrete.expr_with_limits.ExprWithLimits.limits
123
+ sympy.concrete.expr_with_limits.ExprWithLimits.variables
124
+ """
125
+ return super().free_symbols
126
+
127
+ def _eval_is_zero(self):
128
+ # This is a very naive and quick test, not intended to do the integral to
129
+ # answer whether it is zero or not, e.g. Integral(sin(x), (x, 0, 2*pi))
130
+ # is zero but this routine should return None for that case. But, like
131
+ # Mul, there are trivial situations for which the integral will be
132
+ # zero so we check for those.
133
+ if self.function.is_zero:
134
+ return True
135
+ got_none = False
136
+ for l in self.limits:
137
+ if len(l) == 3:
138
+ z = (l[1] == l[2]) or (l[1] - l[2]).is_zero
139
+ if z:
140
+ return True
141
+ elif z is None:
142
+ got_none = True
143
+ free = self.function.free_symbols
144
+ for xab in self.limits:
145
+ if len(xab) == 1:
146
+ free.add(xab[0])
147
+ continue
148
+ if len(xab) == 2 and xab[0] not in free:
149
+ if xab[1].is_zero:
150
+ return True
151
+ elif xab[1].is_zero is None:
152
+ got_none = True
153
+ # take integration symbol out of free since it will be replaced
154
+ # with the free symbols in the limits
155
+ free.discard(xab[0])
156
+ # add in the new symbols
157
+ for i in xab[1:]:
158
+ free.update(i.free_symbols)
159
+ if self.function.is_zero is False and got_none is False:
160
+ return False
161
+
162
+ def transform(self, x, u):
163
+ r"""
164
+ Performs a change of variables from `x` to `u` using the relationship
165
+ given by `x` and `u` which will define the transformations `f` and `F`
166
+ (which are inverses of each other) as follows:
167
+
168
+ 1) If `x` is a Symbol (which is a variable of integration) then `u`
169
+ will be interpreted as some function, f(u), with inverse F(u).
170
+ This, in effect, just makes the substitution of x with f(x).
171
+
172
+ 2) If `u` is a Symbol then `x` will be interpreted as some function,
173
+ F(x), with inverse f(u). This is commonly referred to as
174
+ u-substitution.
175
+
176
+ Once f and F have been identified, the transformation is made as
177
+ follows:
178
+
179
+ .. math:: \int_a^b x \mathrm{d}x \rightarrow \int_{F(a)}^{F(b)} f(x)
180
+ \frac{\mathrm{d}}{\mathrm{d}x}
181
+
182
+ where `F(x)` is the inverse of `f(x)` and the limits and integrand have
183
+ been corrected so as to retain the same value after integration.
184
+
185
+ Notes
186
+ =====
187
+
188
+ The mappings, F(x) or f(u), must lead to a unique integral. Linear
189
+ or rational linear expression, ``2*x``, ``1/x`` and ``sqrt(x)``, will
190
+ always work; quadratic expressions like ``x**2 - 1`` are acceptable
191
+ as long as the resulting integrand does not depend on the sign of
192
+ the solutions (see examples).
193
+
194
+ The integral will be returned unchanged if ``x`` is not a variable of
195
+ integration.
196
+
197
+ ``x`` must be (or contain) only one of of the integration variables. If
198
+ ``u`` has more than one free symbol then it should be sent as a tuple
199
+ (``u``, ``uvar``) where ``uvar`` identifies which variable is replacing
200
+ the integration variable.
201
+ XXX can it contain another integration variable?
202
+
203
+ Examples
204
+ ========
205
+
206
+ >>> from sympy.abc import a, x, u
207
+ >>> from sympy import Integral, cos, sqrt
208
+
209
+ >>> i = Integral(x*cos(x**2 - 1), (x, 0, 1))
210
+
211
+ transform can change the variable of integration
212
+
213
+ >>> i.transform(x, u)
214
+ Integral(u*cos(u**2 - 1), (u, 0, 1))
215
+
216
+ transform can perform u-substitution as long as a unique
217
+ integrand is obtained:
218
+
219
+ >>> i.transform(x**2 - 1, u)
220
+ Integral(cos(u)/2, (u, -1, 0))
221
+
222
+ This attempt fails because x = +/-sqrt(u + 1) and the
223
+ sign does not cancel out of the integrand:
224
+
225
+ >>> Integral(cos(x**2 - 1), (x, 0, 1)).transform(x**2 - 1, u)
226
+ Traceback (most recent call last):
227
+ ...
228
+ ValueError:
229
+ The mapping between F(x) and f(u) did not give a unique integrand.
230
+
231
+ transform can do a substitution. Here, the previous
232
+ result is transformed back into the original expression
233
+ using "u-substitution":
234
+
235
+ >>> ui = _
236
+ >>> _.transform(sqrt(u + 1), x) == i
237
+ True
238
+
239
+ We can accomplish the same with a regular substitution:
240
+
241
+ >>> ui.transform(u, x**2 - 1) == i
242
+ True
243
+
244
+ If the `x` does not contain a symbol of integration then
245
+ the integral will be returned unchanged. Integral `i` does
246
+ not have an integration variable `a` so no change is made:
247
+
248
+ >>> i.transform(a, x) == i
249
+ True
250
+
251
+ When `u` has more than one free symbol the symbol that is
252
+ replacing `x` must be identified by passing `u` as a tuple:
253
+
254
+ >>> Integral(x, (x, 0, 1)).transform(x, (u + a, u))
255
+ Integral(a + u, (u, -a, 1 - a))
256
+ >>> Integral(x, (x, 0, 1)).transform(x, (u + a, a))
257
+ Integral(a + u, (a, -u, 1 - u))
258
+
259
+ See Also
260
+ ========
261
+
262
+ sympy.concrete.expr_with_limits.ExprWithLimits.variables : Lists the integration variables
263
+ as_dummy : Replace integration variables with dummy ones
264
+ """
265
+ d = Dummy('d')
266
+
267
+ xfree = x.free_symbols.intersection(self.variables)
268
+ if len(xfree) > 1:
269
+ raise ValueError(
270
+ 'F(x) can only contain one of: %s' % self.variables)
271
+ xvar = xfree.pop() if xfree else d
272
+
273
+ if xvar not in self.variables:
274
+ return self
275
+
276
+ u = sympify(u)
277
+ if isinstance(u, Expr):
278
+ ufree = u.free_symbols
279
+ if len(ufree) == 0:
280
+ raise ValueError(filldedent('''
281
+ f(u) cannot be a constant'''))
282
+ if len(ufree) > 1:
283
+ raise ValueError(filldedent('''
284
+ When f(u) has more than one free symbol, the one replacing x
285
+ must be identified: pass f(u) as (f(u), u)'''))
286
+ uvar = ufree.pop()
287
+ else:
288
+ u, uvar = u
289
+ if uvar not in u.free_symbols:
290
+ raise ValueError(filldedent('''
291
+ Expecting a tuple (expr, symbol) where symbol identified
292
+ a free symbol in expr, but symbol is not in expr's free
293
+ symbols.'''))
294
+ if not isinstance(uvar, Symbol):
295
+ # This probably never evaluates to True
296
+ raise ValueError(filldedent('''
297
+ Expecting a tuple (expr, symbol) but didn't get
298
+ a symbol; got %s''' % uvar))
299
+
300
+ if x.is_Symbol and u.is_Symbol:
301
+ return self.xreplace({x: u})
302
+
303
+ if not x.is_Symbol and not u.is_Symbol:
304
+ raise ValueError('either x or u must be a symbol')
305
+
306
+ if uvar == xvar:
307
+ return self.transform(x, (u.subs(uvar, d), d)).xreplace({d: uvar})
308
+
309
+ if uvar in self.limits:
310
+ raise ValueError(filldedent('''
311
+ u must contain the same variable as in x
312
+ or a variable that is not already an integration variable'''))
313
+
314
+ from sympy.solvers.solvers import solve
315
+ if not x.is_Symbol:
316
+ F = [x.subs(xvar, d)]
317
+ soln = solve(u - x, xvar, check=False)
318
+ if not soln:
319
+ raise ValueError('no solution for solve(F(x) - f(u), x)')
320
+ f = [fi.subs(uvar, d) for fi in soln]
321
+ else:
322
+ f = [u.subs(uvar, d)]
323
+ from sympy.simplify.simplify import posify
324
+ pdiff, reps = posify(u - x)
325
+ puvar = uvar.subs([(v, k) for k, v in reps.items()])
326
+ soln = [s.subs(reps) for s in solve(pdiff, puvar)]
327
+ if not soln:
328
+ raise ValueError('no solution for solve(F(x) - f(u), u)')
329
+ F = [fi.subs(xvar, d) for fi in soln]
330
+
331
+ newfuncs = {(self.function.subs(xvar, fi)*fi.diff(d)
332
+ ).subs(d, uvar) for fi in f}
333
+ if len(newfuncs) > 1:
334
+ raise ValueError(filldedent('''
335
+ The mapping between F(x) and f(u) did not give
336
+ a unique integrand.'''))
337
+ newfunc = newfuncs.pop()
338
+
339
+ def _calc_limit_1(F, a, b):
340
+ """
341
+ replace d with a, using subs if possible, otherwise limit
342
+ where sign of b is considered
343
+ """
344
+ wok = F.subs(d, a)
345
+ if wok is S.NaN or wok.is_finite is False and a.is_finite:
346
+ return limit(sign(b)*F, d, a)
347
+ return wok
348
+
349
+ def _calc_limit(a, b):
350
+ """
351
+ replace d with a, using subs if possible, otherwise limit
352
+ where sign of b is considered
353
+ """
354
+ avals = list({_calc_limit_1(Fi, a, b) for Fi in F})
355
+ if len(avals) > 1:
356
+ raise ValueError(filldedent('''
357
+ The mapping between F(x) and f(u) did not
358
+ give a unique limit.'''))
359
+ return avals[0]
360
+
361
+ newlimits = []
362
+ for xab in self.limits:
363
+ sym = xab[0]
364
+ if sym == xvar:
365
+ if len(xab) == 3:
366
+ a, b = xab[1:]
367
+ a, b = _calc_limit(a, b), _calc_limit(b, a)
368
+ if fuzzy_bool(a - b > 0):
369
+ a, b = b, a
370
+ newfunc = -newfunc
371
+ newlimits.append((uvar, a, b))
372
+ elif len(xab) == 2:
373
+ a = _calc_limit(xab[1], 1)
374
+ newlimits.append((uvar, a))
375
+ else:
376
+ newlimits.append(uvar)
377
+ else:
378
+ newlimits.append(xab)
379
+
380
+ return self.func(newfunc, *newlimits)
381
+
382
+ def doit(self, **hints):
383
+ """
384
+ Perform the integration using any hints given.
385
+
386
+ Examples
387
+ ========
388
+
389
+ >>> from sympy import Piecewise, S
390
+ >>> from sympy.abc import x, t
391
+ >>> p = x**2 + Piecewise((0, x/t < 0), (1, True))
392
+ >>> p.integrate((t, S(4)/5, 1), (x, -1, 1))
393
+ 1/3
394
+
395
+ See Also
396
+ ========
397
+
398
+ sympy.integrals.trigonometry.trigintegrate
399
+ sympy.integrals.heurisch.heurisch
400
+ sympy.integrals.rationaltools.ratint
401
+ as_sum : Approximate the integral using a sum
402
+ """
403
+ if not hints.get('integrals', True):
404
+ return self
405
+
406
+ deep = hints.get('deep', True)
407
+ meijerg = hints.get('meijerg', None)
408
+ conds = hints.get('conds', 'piecewise')
409
+ risch = hints.get('risch', None)
410
+ heurisch = hints.get('heurisch', None)
411
+ manual = hints.get('manual', None)
412
+ if len(list(filter(None, (manual, meijerg, risch, heurisch)))) > 1:
413
+ raise ValueError("At most one of manual, meijerg, risch, heurisch can be True")
414
+ elif manual:
415
+ meijerg = risch = heurisch = False
416
+ elif meijerg:
417
+ manual = risch = heurisch = False
418
+ elif risch:
419
+ manual = meijerg = heurisch = False
420
+ elif heurisch:
421
+ manual = meijerg = risch = False
422
+ eval_kwargs = {"meijerg": meijerg, "risch": risch, "manual": manual, "heurisch": heurisch,
423
+ "conds": conds}
424
+
425
+ if conds not in ('separate', 'piecewise', 'none'):
426
+ raise ValueError('conds must be one of "separate", "piecewise", '
427
+ '"none", got: %s' % conds)
428
+
429
+ if risch and any(len(xab) > 1 for xab in self.limits):
430
+ raise ValueError('risch=True is only allowed for indefinite integrals.')
431
+
432
+ # check for the trivial zero
433
+ if self.is_zero:
434
+ return S.Zero
435
+
436
+ # hacks to handle integrals of
437
+ # nested summations
438
+ from sympy.concrete.summations import Sum
439
+ if isinstance(self.function, Sum):
440
+ if any(v in self.function.limits[0] for v in self.variables):
441
+ raise ValueError('Limit of the sum cannot be an integration variable.')
442
+ if any(l.is_infinite for l in self.function.limits[0][1:]):
443
+ return self
444
+ _i = self
445
+ _sum = self.function
446
+ return _sum.func(_i.func(_sum.function, *_i.limits).doit(), *_sum.limits).doit()
447
+
448
+ # now compute and check the function
449
+ function = self.function
450
+ if deep:
451
+ function = function.doit(**hints)
452
+ if function.is_zero:
453
+ return S.Zero
454
+
455
+ # hacks to handle special cases
456
+ if isinstance(function, MatrixBase):
457
+ return function.applyfunc(
458
+ lambda f: self.func(f, *self.limits).doit(**hints))
459
+
460
+ if isinstance(function, FormalPowerSeries):
461
+ if len(self.limits) > 1:
462
+ raise NotImplementedError
463
+ xab = self.limits[0]
464
+ if len(xab) > 1:
465
+ return function.integrate(xab, **eval_kwargs)
466
+ else:
467
+ return function.integrate(xab[0], **eval_kwargs)
468
+
469
+ # There is no trivial answer and special handling
470
+ # is done so continue
471
+
472
+ # first make sure any definite limits have integration
473
+ # variables with matching assumptions
474
+ reps = {}
475
+ for xab in self.limits:
476
+ if len(xab) != 3:
477
+ # it makes sense to just make
478
+ # all x real but in practice with the
479
+ # current state of integration...this
480
+ # doesn't work out well
481
+ # x = xab[0]
482
+ # if x not in reps and not x.is_real:
483
+ # reps[x] = Dummy(real=True)
484
+ continue
485
+ x, a, b = xab
486
+ l = (a, b)
487
+ if all(i.is_nonnegative for i in l) and not x.is_nonnegative:
488
+ d = Dummy(positive=True)
489
+ elif all(i.is_nonpositive for i in l) and not x.is_nonpositive:
490
+ d = Dummy(negative=True)
491
+ elif all(i.is_real for i in l) and not x.is_real:
492
+ d = Dummy(real=True)
493
+ else:
494
+ d = None
495
+ if d:
496
+ reps[x] = d
497
+ if reps:
498
+ undo = {v: k for k, v in reps.items()}
499
+ did = self.xreplace(reps).doit(**hints)
500
+ if isinstance(did, tuple): # when separate=True
501
+ did = tuple([i.xreplace(undo) for i in did])
502
+ else:
503
+ did = did.xreplace(undo)
504
+ return did
505
+
506
+ # continue with existing assumptions
507
+ undone_limits = []
508
+ # ulj = free symbols of any undone limits' upper and lower limits
509
+ ulj = set()
510
+ for xab in self.limits:
511
+ # compute uli, the free symbols in the
512
+ # Upper and Lower limits of limit I
513
+ if len(xab) == 1:
514
+ uli = set(xab[:1])
515
+ elif len(xab) == 2:
516
+ uli = xab[1].free_symbols
517
+ elif len(xab) == 3:
518
+ uli = xab[1].free_symbols.union(xab[2].free_symbols)
519
+ # this integral can be done as long as there is no blocking
520
+ # limit that has been undone. An undone limit is blocking if
521
+ # it contains an integration variable that is in this limit's
522
+ # upper or lower free symbols or vice versa
523
+ if xab[0] in ulj or any(v[0] in uli for v in undone_limits):
524
+ undone_limits.append(xab)
525
+ ulj.update(uli)
526
+ function = self.func(*([function] + [xab]))
527
+ factored_function = function.factor()
528
+ if not isinstance(factored_function, Integral):
529
+ function = factored_function
530
+ continue
531
+
532
+ if function.has(Abs, sign) and (
533
+ (len(xab) < 3 and all(x.is_extended_real for x in xab)) or
534
+ (len(xab) == 3 and all(x.is_extended_real and not x.is_infinite for
535
+ x in xab[1:]))):
536
+ # some improper integrals are better off with Abs
537
+ xr = Dummy("xr", real=True)
538
+ function = (function.xreplace({xab[0]: xr})
539
+ .rewrite(Piecewise).xreplace({xr: xab[0]}))
540
+ elif function.has(Min, Max):
541
+ function = function.rewrite(Piecewise)
542
+ if (function.has(Piecewise) and
543
+ not isinstance(function, Piecewise)):
544
+ function = piecewise_fold(function)
545
+ if isinstance(function, Piecewise):
546
+ if len(xab) == 1:
547
+ antideriv = function._eval_integral(xab[0],
548
+ **eval_kwargs)
549
+ else:
550
+ antideriv = self._eval_integral(
551
+ function, xab[0], **eval_kwargs)
552
+ else:
553
+ # There are a number of tradeoffs in using the
554
+ # Meijer G method. It can sometimes be a lot faster
555
+ # than other methods, and sometimes slower. And
556
+ # there are certain types of integrals for which it
557
+ # is more likely to work than others. These
558
+ # heuristics are incorporated in deciding what
559
+ # integration methods to try, in what order. See the
560
+ # integrate() docstring for details.
561
+ def try_meijerg(function, xab):
562
+ ret = None
563
+ if len(xab) == 3 and meijerg is not False:
564
+ x, a, b = xab
565
+ try:
566
+ res = meijerint_definite(function, x, a, b)
567
+ except NotImplementedError:
568
+ _debug('NotImplementedError '
569
+ 'from meijerint_definite')
570
+ res = None
571
+ if res is not None:
572
+ f, cond = res
573
+ if conds == 'piecewise':
574
+ u = self.func(function, (x, a, b))
575
+ # if Piecewise modifies cond too
576
+ # much it may not be recognized by
577
+ # _condsimp pattern matching so just
578
+ # turn off all evaluation
579
+ return Piecewise((f, cond), (u, True),
580
+ evaluate=False)
581
+ elif conds == 'separate':
582
+ if len(self.limits) != 1:
583
+ raise ValueError(filldedent('''
584
+ conds=separate not supported in
585
+ multiple integrals'''))
586
+ ret = f, cond
587
+ else:
588
+ ret = f
589
+ return ret
590
+
591
+ meijerg1 = meijerg
592
+ if (meijerg is not False and
593
+ len(xab) == 3 and xab[1].is_extended_real and xab[2].is_extended_real
594
+ and not function.is_Poly and
595
+ (xab[1].has(oo, -oo) or xab[2].has(oo, -oo))):
596
+ ret = try_meijerg(function, xab)
597
+ if ret is not None:
598
+ function = ret
599
+ continue
600
+ meijerg1 = False
601
+ # If the special meijerg code did not succeed in
602
+ # finding a definite integral, then the code using
603
+ # meijerint_indefinite will not either (it might
604
+ # find an antiderivative, but the answer is likely
605
+ # to be nonsensical). Thus if we are requested to
606
+ # only use Meijer G-function methods, we give up at
607
+ # this stage. Otherwise we just disable G-function
608
+ # methods.
609
+ if meijerg1 is False and meijerg is True:
610
+ antideriv = None
611
+ else:
612
+ antideriv = self._eval_integral(
613
+ function, xab[0], **eval_kwargs)
614
+ if antideriv is None and meijerg is True:
615
+ ret = try_meijerg(function, xab)
616
+ if ret is not None:
617
+ function = ret
618
+ continue
619
+
620
+ final = hints.get('final', True)
621
+ # dotit may be iterated but floor terms making atan and acot
622
+ # continuous should only be added in the final round
623
+ if (final and not isinstance(antideriv, Integral) and
624
+ antideriv is not None):
625
+ for atan_term in antideriv.atoms(atan):
626
+ atan_arg = atan_term.args[0]
627
+ # Checking `atan_arg` to be linear combination of `tan` or `cot`
628
+ for tan_part in atan_arg.atoms(tan):
629
+ x1 = Dummy('x1')
630
+ tan_exp1 = atan_arg.subs(tan_part, x1)
631
+ # The coefficient of `tan` should be constant
632
+ coeff = tan_exp1.diff(x1)
633
+ if x1 not in coeff.free_symbols:
634
+ a = tan_part.args[0]
635
+ antideriv = antideriv.subs(atan_term, Add(atan_term,
636
+ sign(coeff)*pi*floor((a-pi/2)/pi)))
637
+ for cot_part in atan_arg.atoms(cot):
638
+ x1 = Dummy('x1')
639
+ cot_exp1 = atan_arg.subs(cot_part, x1)
640
+ # The coefficient of `cot` should be constant
641
+ coeff = cot_exp1.diff(x1)
642
+ if x1 not in coeff.free_symbols:
643
+ a = cot_part.args[0]
644
+ antideriv = antideriv.subs(atan_term, Add(atan_term,
645
+ sign(coeff)*pi*floor((a)/pi)))
646
+
647
+ if antideriv is None:
648
+ undone_limits.append(xab)
649
+ function = self.func(*([function] + [xab])).factor()
650
+ factored_function = function.factor()
651
+ if not isinstance(factored_function, Integral):
652
+ function = factored_function
653
+ continue
654
+ else:
655
+ if len(xab) == 1:
656
+ function = antideriv
657
+ else:
658
+ if len(xab) == 3:
659
+ x, a, b = xab
660
+ elif len(xab) == 2:
661
+ x, b = xab
662
+ a = None
663
+ else:
664
+ raise NotImplementedError
665
+
666
+ if deep:
667
+ if isinstance(a, Basic):
668
+ a = a.doit(**hints)
669
+ if isinstance(b, Basic):
670
+ b = b.doit(**hints)
671
+
672
+ if antideriv.is_Poly:
673
+ gens = list(antideriv.gens)
674
+ gens.remove(x)
675
+
676
+ antideriv = antideriv.as_expr()
677
+
678
+ function = antideriv._eval_interval(x, a, b)
679
+ function = Poly(function, *gens)
680
+ else:
681
+ def is_indef_int(g, x):
682
+ return (isinstance(g, Integral) and
683
+ any(i == (x,) for i in g.limits))
684
+
685
+ def eval_factored(f, x, a, b):
686
+ # _eval_interval for integrals with
687
+ # (constant) factors
688
+ # a single indefinite integral is assumed
689
+ args = []
690
+ for g in Mul.make_args(f):
691
+ if is_indef_int(g, x):
692
+ args.append(g._eval_interval(x, a, b))
693
+ else:
694
+ args.append(g)
695
+ return Mul(*args)
696
+
697
+ integrals, others, piecewises = [], [], []
698
+ for f in Add.make_args(antideriv):
699
+ if any(is_indef_int(g, x)
700
+ for g in Mul.make_args(f)):
701
+ integrals.append(f)
702
+ elif any(isinstance(g, Piecewise)
703
+ for g in Mul.make_args(f)):
704
+ piecewises.append(piecewise_fold(f))
705
+ else:
706
+ others.append(f)
707
+ uneval = Add(*[eval_factored(f, x, a, b)
708
+ for f in integrals])
709
+ try:
710
+ evalued = Add(*others)._eval_interval(x, a, b)
711
+ evalued_pw = piecewise_fold(Add(*piecewises))._eval_interval(x, a, b)
712
+ function = uneval + evalued + evalued_pw
713
+ except NotImplementedError:
714
+ # This can happen if _eval_interval depends in a
715
+ # complicated way on limits that cannot be computed
716
+ undone_limits.append(xab)
717
+ function = self.func(*([function] + [xab]))
718
+ factored_function = function.factor()
719
+ if not isinstance(factored_function, Integral):
720
+ function = factored_function
721
+ return function
722
+
723
+ def _eval_derivative(self, sym):
724
+ """Evaluate the derivative of the current Integral object by
725
+ differentiating under the integral sign [1], using the Fundamental
726
+ Theorem of Calculus [2] when possible.
727
+
728
+ Explanation
729
+ ===========
730
+
731
+ Whenever an Integral is encountered that is equivalent to zero or
732
+ has an integrand that is independent of the variable of integration
733
+ those integrals are performed. All others are returned as Integral
734
+ instances which can be resolved with doit() (provided they are integrable).
735
+
736
+ References
737
+ ==========
738
+
739
+ .. [1] https://en.wikipedia.org/wiki/Differentiation_under_the_integral_sign
740
+ .. [2] https://en.wikipedia.org/wiki/Fundamental_theorem_of_calculus
741
+
742
+ Examples
743
+ ========
744
+
745
+ >>> from sympy import Integral
746
+ >>> from sympy.abc import x, y
747
+ >>> i = Integral(x + y, y, (y, 1, x))
748
+ >>> i.diff(x)
749
+ Integral(x + y, (y, x)) + Integral(1, y, (y, 1, x))
750
+ >>> i.doit().diff(x) == i.diff(x).doit()
751
+ True
752
+ >>> i.diff(y)
753
+ 0
754
+
755
+ The previous must be true since there is no y in the evaluated integral:
756
+
757
+ >>> i.free_symbols
758
+ {x}
759
+ >>> i.doit()
760
+ 2*x**3/3 - x/2 - 1/6
761
+
762
+ """
763
+
764
+ # differentiate under the integral sign; we do not
765
+ # check for regularity conditions (TODO), see issue 4215
766
+
767
+ # get limits and the function
768
+ f, limits = self.function, list(self.limits)
769
+
770
+ # the order matters if variables of integration appear in the limits
771
+ # so work our way in from the outside to the inside.
772
+ limit = limits.pop(-1)
773
+ if len(limit) == 3:
774
+ x, a, b = limit
775
+ elif len(limit) == 2:
776
+ x, b = limit
777
+ a = None
778
+ else:
779
+ a = b = None
780
+ x = limit[0]
781
+
782
+ if limits: # f is the argument to an integral
783
+ f = self.func(f, *tuple(limits))
784
+
785
+ # assemble the pieces
786
+ def _do(f, ab):
787
+ dab_dsym = diff(ab, sym)
788
+ if not dab_dsym:
789
+ return S.Zero
790
+ if isinstance(f, Integral):
791
+ limits = [(x, x) if (len(l) == 1 and l[0] == x) else l
792
+ for l in f.limits]
793
+ f = self.func(f.function, *limits)
794
+ return f.subs(x, ab)*dab_dsym
795
+
796
+ rv = S.Zero
797
+ if b is not None:
798
+ rv += _do(f, b)
799
+ if a is not None:
800
+ rv -= _do(f, a)
801
+ if len(limit) == 1 and sym == x:
802
+ # the dummy variable *is* also the real-world variable
803
+ arg = f
804
+ rv += arg
805
+ else:
806
+ # the dummy variable might match sym but it's
807
+ # only a dummy and the actual variable is determined
808
+ # by the limits, so mask off the variable of integration
809
+ # while differentiating
810
+ u = Dummy('u')
811
+ arg = f.subs(x, u).diff(sym).subs(u, x)
812
+ if arg:
813
+ rv += self.func(arg, (x, a, b))
814
+ return rv
815
+
816
+ def _eval_integral(self, f, x, meijerg=None, risch=None, manual=None,
817
+ heurisch=None, conds='piecewise',final=None):
818
+ """
819
+ Calculate the anti-derivative to the function f(x).
820
+
821
+ Explanation
822
+ ===========
823
+
824
+ The following algorithms are applied (roughly in this order):
825
+
826
+ 1. Simple heuristics (based on pattern matching and integral table):
827
+
828
+ - most frequently used functions (e.g. polynomials, products of
829
+ trig functions)
830
+
831
+ 2. Integration of rational functions:
832
+
833
+ - A complete algorithm for integrating rational functions is
834
+ implemented (the Lazard-Rioboo-Trager algorithm). The algorithm
835
+ also uses the partial fraction decomposition algorithm
836
+ implemented in apart() as a preprocessor to make this process
837
+ faster. Note that the integral of a rational function is always
838
+ elementary, but in general, it may include a RootSum.
839
+
840
+ 3. Full Risch algorithm:
841
+
842
+ - The Risch algorithm is a complete decision
843
+ procedure for integrating elementary functions, which means that
844
+ given any elementary function, it will either compute an
845
+ elementary antiderivative, or else prove that none exists.
846
+ Currently, part of transcendental case is implemented, meaning
847
+ elementary integrals containing exponentials, logarithms, and
848
+ (soon!) trigonometric functions can be computed. The algebraic
849
+ case, e.g., functions containing roots, is much more difficult
850
+ and is not implemented yet.
851
+
852
+ - If the routine fails (because the integrand is not elementary, or
853
+ because a case is not implemented yet), it continues on to the
854
+ next algorithms below. If the routine proves that the integrals
855
+ is nonelementary, it still moves on to the algorithms below,
856
+ because we might be able to find a closed-form solution in terms
857
+ of special functions. If risch=True, however, it will stop here.
858
+
859
+ 4. The Meijer G-Function algorithm:
860
+
861
+ - This algorithm works by first rewriting the integrand in terms of
862
+ very general Meijer G-Function (meijerg in SymPy), integrating
863
+ it, and then rewriting the result back, if possible. This
864
+ algorithm is particularly powerful for definite integrals (which
865
+ is actually part of a different method of Integral), since it can
866
+ compute closed-form solutions of definite integrals even when no
867
+ closed-form indefinite integral exists. But it also is capable
868
+ of computing many indefinite integrals as well.
869
+
870
+ - Another advantage of this method is that it can use some results
871
+ about the Meijer G-Function to give a result in terms of a
872
+ Piecewise expression, which allows to express conditionally
873
+ convergent integrals.
874
+
875
+ - Setting meijerg=True will cause integrate() to use only this
876
+ method.
877
+
878
+ 5. The "manual integration" algorithm:
879
+
880
+ - This algorithm tries to mimic how a person would find an
881
+ antiderivative by hand, for example by looking for a
882
+ substitution or applying integration by parts. This algorithm
883
+ does not handle as many integrands but can return results in a
884
+ more familiar form.
885
+
886
+ - Sometimes this algorithm can evaluate parts of an integral; in
887
+ this case integrate() will try to evaluate the rest of the
888
+ integrand using the other methods here.
889
+
890
+ - Setting manual=True will cause integrate() to use only this
891
+ method.
892
+
893
+ 6. The Heuristic Risch algorithm:
894
+
895
+ - This is a heuristic version of the Risch algorithm, meaning that
896
+ it is not deterministic. This is tried as a last resort because
897
+ it can be very slow. It is still used because not enough of the
898
+ full Risch algorithm is implemented, so that there are still some
899
+ integrals that can only be computed using this method. The goal
900
+ is to implement enough of the Risch and Meijer G-function methods
901
+ so that this can be deleted.
902
+
903
+ Setting heurisch=True will cause integrate() to use only this
904
+ method. Set heurisch=False to not use it.
905
+
906
+ """
907
+
908
+ from sympy.integrals.risch import risch_integrate, NonElementaryIntegral
909
+ from sympy.integrals.manualintegrate import manualintegrate
910
+
911
+ if risch:
912
+ try:
913
+ return risch_integrate(f, x, conds=conds)
914
+ except NotImplementedError:
915
+ return None
916
+
917
+ if manual:
918
+ try:
919
+ result = manualintegrate(f, x)
920
+ if result is not None and result.func != Integral:
921
+ return result
922
+ except (ValueError, PolynomialError):
923
+ pass
924
+
925
+ eval_kwargs = {"meijerg": meijerg, "risch": risch, "manual": manual,
926
+ "heurisch": heurisch, "conds": conds}
927
+
928
+ # if it is a poly(x) then let the polynomial integrate itself (fast)
929
+ #
930
+ # It is important to make this check first, otherwise the other code
931
+ # will return a SymPy expression instead of a Polynomial.
932
+ #
933
+ # see Polynomial for details.
934
+ if isinstance(f, Poly) and not (manual or meijerg or risch):
935
+ # Note: this is deprecated, but the deprecation warning is already
936
+ # issued in the Integral constructor.
937
+ return f.integrate(x)
938
+
939
+ # Piecewise antiderivatives need to call special integrate.
940
+ if isinstance(f, Piecewise):
941
+ return f.piecewise_integrate(x, **eval_kwargs)
942
+
943
+ # let's cut it short if `f` does not depend on `x`; if
944
+ # x is only a dummy, that will be handled below
945
+ if not f.has(x):
946
+ return f*x
947
+
948
+ # try to convert to poly(x) and then integrate if successful (fast)
949
+ poly = f.as_poly(x)
950
+ if poly is not None and not (manual or meijerg or risch):
951
+ return poly.integrate().as_expr()
952
+
953
+ if risch is not False:
954
+ try:
955
+ result, i = risch_integrate(f, x, separate_integral=True,
956
+ conds=conds)
957
+ except NotImplementedError:
958
+ pass
959
+ else:
960
+ if i:
961
+ # There was a nonelementary integral. Try integrating it.
962
+
963
+ # if no part of the NonElementaryIntegral is integrated by
964
+ # the Risch algorithm, then use the original function to
965
+ # integrate, instead of re-written one
966
+ if result == 0:
967
+ return NonElementaryIntegral(f, x).doit(risch=False)
968
+ else:
969
+ return result + i.doit(risch=False)
970
+ else:
971
+ return result
972
+
973
+ # since Integral(f=g1+g2+...) == Integral(g1) + Integral(g2) + ...
974
+ # we are going to handle Add terms separately,
975
+ # if `f` is not Add -- we only have one term
976
+
977
+ # Note that in general, this is a bad idea, because Integral(g1) +
978
+ # Integral(g2) might not be computable, even if Integral(g1 + g2) is.
979
+ # For example, Integral(x**x + x**x*log(x)). But many heuristics only
980
+ # work term-wise. So we compute this step last, after trying
981
+ # risch_integrate. We also try risch_integrate again in this loop,
982
+ # because maybe the integral is a sum of an elementary part and a
983
+ # nonelementary part (like erf(x) + exp(x)). risch_integrate() is
984
+ # quite fast, so this is acceptable.
985
+ from sympy.simplify.fu import sincos_to_sum
986
+ parts = []
987
+ args = Add.make_args(f)
988
+ for g in args:
989
+ coeff, g = g.as_independent(x)
990
+
991
+ # g(x) = const
992
+ if g is S.One and not meijerg:
993
+ parts.append(coeff*x)
994
+ continue
995
+
996
+ # g(x) = expr + O(x**n)
997
+ order_term = g.getO()
998
+
999
+ if order_term is not None:
1000
+ h = self._eval_integral(g.removeO(), x, **eval_kwargs)
1001
+
1002
+ if h is not None:
1003
+ h_order_expr = self._eval_integral(order_term.expr, x, **eval_kwargs)
1004
+
1005
+ if h_order_expr is not None:
1006
+ h_order_term = order_term.func(
1007
+ h_order_expr, *order_term.variables)
1008
+ parts.append(coeff*(h + h_order_term))
1009
+ continue
1010
+
1011
+ # NOTE: if there is O(x**n) and we fail to integrate then
1012
+ # there is no point in trying other methods because they
1013
+ # will fail, too.
1014
+ return None
1015
+
1016
+ # c
1017
+ # g(x) = (a*x+b)
1018
+ if g.is_Pow and not g.exp.has(x) and not meijerg:
1019
+ a = Wild('a', exclude=[x])
1020
+ b = Wild('b', exclude=[x])
1021
+
1022
+ M = g.base.match(a*x + b)
1023
+
1024
+ if M is not None:
1025
+ if g.exp == -1:
1026
+ h = log(g.base)
1027
+ elif conds != 'piecewise':
1028
+ h = g.base**(g.exp + 1) / (g.exp + 1)
1029
+ else:
1030
+ h1 = log(g.base)
1031
+ h2 = g.base**(g.exp + 1) / (g.exp + 1)
1032
+ h = Piecewise((h2, Ne(g.exp, -1)), (h1, True))
1033
+
1034
+ parts.append(coeff * h / M[a])
1035
+ continue
1036
+
1037
+ # poly(x)
1038
+ # g(x) = -------
1039
+ # poly(x)
1040
+ if g.is_rational_function(x) and not (manual or meijerg or risch):
1041
+ parts.append(coeff * ratint(g, x))
1042
+ continue
1043
+
1044
+ if not (manual or meijerg or risch):
1045
+ # g(x) = Mul(trig)
1046
+ h = trigintegrate(g, x, conds=conds)
1047
+ if h is not None:
1048
+ parts.append(coeff * h)
1049
+ continue
1050
+
1051
+ # g(x) has at least a DiracDelta term
1052
+ h = deltaintegrate(g, x)
1053
+ if h is not None:
1054
+ parts.append(coeff * h)
1055
+ continue
1056
+
1057
+ from .singularityfunctions import singularityintegrate
1058
+ # g(x) has at least a Singularity Function term
1059
+ h = singularityintegrate(g, x)
1060
+ if h is not None:
1061
+ parts.append(coeff * h)
1062
+ continue
1063
+
1064
+ # Try risch again.
1065
+ if risch is not False:
1066
+ try:
1067
+ h, i = risch_integrate(g, x,
1068
+ separate_integral=True, conds=conds)
1069
+ except NotImplementedError:
1070
+ h = None
1071
+ else:
1072
+ if i:
1073
+ h = h + i.doit(risch=False)
1074
+
1075
+ parts.append(coeff*h)
1076
+ continue
1077
+
1078
+ # fall back to heurisch
1079
+ if heurisch is not False:
1080
+ from sympy.integrals.heurisch import (heurisch as heurisch_,
1081
+ heurisch_wrapper)
1082
+ try:
1083
+ if conds == 'piecewise':
1084
+ h = heurisch_wrapper(g, x, hints=[])
1085
+ else:
1086
+ h = heurisch_(g, x, hints=[])
1087
+ except PolynomialError:
1088
+ # XXX: this exception means there is a bug in the
1089
+ # implementation of heuristic Risch integration
1090
+ # algorithm.
1091
+ h = None
1092
+ else:
1093
+ h = None
1094
+
1095
+ if meijerg is not False and h is None:
1096
+ # rewrite using G functions
1097
+ try:
1098
+ h = meijerint_indefinite(g, x)
1099
+ except NotImplementedError:
1100
+ _debug('NotImplementedError from meijerint_definite')
1101
+ if h is not None:
1102
+ parts.append(coeff * h)
1103
+ continue
1104
+
1105
+ if h is None and manual is not False:
1106
+ try:
1107
+ result = manualintegrate(g, x)
1108
+ if result is not None and not isinstance(result, Integral):
1109
+ if result.has(Integral) and not manual:
1110
+ # Try to have other algorithms do the integrals
1111
+ # manualintegrate can't handle,
1112
+ # unless we were asked to use manual only.
1113
+ # Keep the rest of eval_kwargs in case another
1114
+ # method was set to False already
1115
+ new_eval_kwargs = eval_kwargs
1116
+ new_eval_kwargs["manual"] = False
1117
+ new_eval_kwargs["final"] = False
1118
+ result = result.func(*[
1119
+ arg.doit(**new_eval_kwargs) if
1120
+ arg.has(Integral) else arg
1121
+ for arg in result.args
1122
+ ]).expand(multinomial=False,
1123
+ log=False,
1124
+ power_exp=False,
1125
+ power_base=False)
1126
+ if not result.has(Integral):
1127
+ parts.append(coeff * result)
1128
+ continue
1129
+ except (ValueError, PolynomialError):
1130
+ # can't handle some SymPy expressions
1131
+ pass
1132
+
1133
+ # if we failed maybe it was because we had
1134
+ # a product that could have been expanded,
1135
+ # so let's try an expansion of the whole
1136
+ # thing before giving up; we don't try this
1137
+ # at the outset because there are things
1138
+ # that cannot be solved unless they are
1139
+ # NOT expanded e.g., x**x*(1+log(x)). There
1140
+ # should probably be a checker somewhere in this
1141
+ # routine to look for such cases and try to do
1142
+ # collection on the expressions if they are already
1143
+ # in an expanded form
1144
+ if not h and len(args) == 1:
1145
+ f = sincos_to_sum(f).expand(mul=True, deep=False)
1146
+ if f.is_Add:
1147
+ # Note: risch will be identical on the expanded
1148
+ # expression, but maybe it will be able to pick out parts,
1149
+ # like x*(exp(x) + erf(x)).
1150
+ return self._eval_integral(f, x, **eval_kwargs)
1151
+
1152
+ if h is not None:
1153
+ parts.append(coeff * h)
1154
+ else:
1155
+ return None
1156
+
1157
+ return Add(*parts)
1158
+
1159
+ def _eval_lseries(self, x, logx=None, cdir=0):
1160
+ expr = self.as_dummy()
1161
+ symb = x
1162
+ for l in expr.limits:
1163
+ if x in l[1:]:
1164
+ symb = l[0]
1165
+ break
1166
+ for term in expr.function.lseries(symb, logx):
1167
+ yield integrate(term, *expr.limits)
1168
+
1169
+ def _eval_nseries(self, x, n, logx=None, cdir=0):
1170
+ expr = self.as_dummy()
1171
+ symb = x
1172
+ for l in expr.limits:
1173
+ if x in l[1:]:
1174
+ symb = l[0]
1175
+ break
1176
+ terms, order = expr.function.nseries(
1177
+ x=symb, n=n, logx=logx).as_coeff_add(Order)
1178
+ order = [o.subs(symb, x) for o in order]
1179
+ return integrate(terms, *expr.limits) + Add(*order)*x
1180
+
1181
+ def _eval_as_leading_term(self, x, logx=None, cdir=0):
1182
+ series_gen = self.args[0].lseries(x)
1183
+ for leading_term in series_gen:
1184
+ if leading_term != 0:
1185
+ break
1186
+ return integrate(leading_term, *self.args[1:])
1187
+
1188
+ def _eval_simplify(self, **kwargs):
1189
+ expr = factor_terms(self)
1190
+ if isinstance(expr, Integral):
1191
+ from sympy.simplify.simplify import simplify
1192
+ return expr.func(*[simplify(i, **kwargs) for i in expr.args])
1193
+ return expr.simplify(**kwargs)
1194
+
1195
+ def as_sum(self, n=None, method="midpoint", evaluate=True):
1196
+ """
1197
+ Approximates a definite integral by a sum.
1198
+
1199
+ Parameters
1200
+ ==========
1201
+
1202
+ n :
1203
+ The number of subintervals to use, optional.
1204
+ method :
1205
+ One of: 'left', 'right', 'midpoint', 'trapezoid'.
1206
+ evaluate : bool
1207
+ If False, returns an unevaluated Sum expression. The default
1208
+ is True, evaluate the sum.
1209
+
1210
+ Notes
1211
+ =====
1212
+
1213
+ These methods of approximate integration are described in [1].
1214
+
1215
+ Examples
1216
+ ========
1217
+
1218
+ >>> from sympy import Integral, sin, sqrt
1219
+ >>> from sympy.abc import x, n
1220
+ >>> e = Integral(sin(x), (x, 3, 7))
1221
+ >>> e
1222
+ Integral(sin(x), (x, 3, 7))
1223
+
1224
+ For demonstration purposes, this interval will only be split into 2
1225
+ regions, bounded by [3, 5] and [5, 7].
1226
+
1227
+ The left-hand rule uses function evaluations at the left of each
1228
+ interval:
1229
+
1230
+ >>> e.as_sum(2, 'left')
1231
+ 2*sin(5) + 2*sin(3)
1232
+
1233
+ The midpoint rule uses evaluations at the center of each interval:
1234
+
1235
+ >>> e.as_sum(2, 'midpoint')
1236
+ 2*sin(4) + 2*sin(6)
1237
+
1238
+ The right-hand rule uses function evaluations at the right of each
1239
+ interval:
1240
+
1241
+ >>> e.as_sum(2, 'right')
1242
+ 2*sin(5) + 2*sin(7)
1243
+
1244
+ The trapezoid rule uses function evaluations on both sides of the
1245
+ intervals. This is equivalent to taking the average of the left and
1246
+ right hand rule results:
1247
+
1248
+ >>> e.as_sum(2, 'trapezoid')
1249
+ 2*sin(5) + sin(3) + sin(7)
1250
+ >>> (e.as_sum(2, 'left') + e.as_sum(2, 'right'))/2 == _
1251
+ True
1252
+
1253
+ Here, the discontinuity at x = 0 can be avoided by using the
1254
+ midpoint or right-hand method:
1255
+
1256
+ >>> e = Integral(1/sqrt(x), (x, 0, 1))
1257
+ >>> e.as_sum(5).n(4)
1258
+ 1.730
1259
+ >>> e.as_sum(10).n(4)
1260
+ 1.809
1261
+ >>> e.doit().n(4) # the actual value is 2
1262
+ 2.000
1263
+
1264
+ The left- or trapezoid method will encounter the discontinuity and
1265
+ return infinity:
1266
+
1267
+ >>> e.as_sum(5, 'left')
1268
+ zoo
1269
+
1270
+ The number of intervals can be symbolic. If omitted, a dummy symbol
1271
+ will be used for it.
1272
+
1273
+ >>> e = Integral(x**2, (x, 0, 2))
1274
+ >>> e.as_sum(n, 'right').expand()
1275
+ 8/3 + 4/n + 4/(3*n**2)
1276
+
1277
+ This shows that the midpoint rule is more accurate, as its error
1278
+ term decays as the square of n:
1279
+
1280
+ >>> e.as_sum(method='midpoint').expand()
1281
+ 8/3 - 2/(3*_n**2)
1282
+
1283
+ A symbolic sum is returned with evaluate=False:
1284
+
1285
+ >>> e.as_sum(n, 'midpoint', evaluate=False)
1286
+ 2*Sum((2*_k/n - 1/n)**2, (_k, 1, n))/n
1287
+
1288
+ See Also
1289
+ ========
1290
+
1291
+ Integral.doit : Perform the integration using any hints
1292
+
1293
+ References
1294
+ ==========
1295
+
1296
+ .. [1] https://en.wikipedia.org/wiki/Riemann_sum#Riemann_summation_methods
1297
+ """
1298
+
1299
+ from sympy.concrete.summations import Sum
1300
+ limits = self.limits
1301
+ if len(limits) > 1:
1302
+ raise NotImplementedError(
1303
+ "Multidimensional midpoint rule not implemented yet")
1304
+ else:
1305
+ limit = limits[0]
1306
+ if (len(limit) != 3 or limit[1].is_finite is False or
1307
+ limit[2].is_finite is False):
1308
+ raise ValueError("Expecting a definite integral over "
1309
+ "a finite interval.")
1310
+ if n is None:
1311
+ n = Dummy('n', integer=True, positive=True)
1312
+ else:
1313
+ n = sympify(n)
1314
+ if (n.is_positive is False or n.is_integer is False or
1315
+ n.is_finite is False):
1316
+ raise ValueError("n must be a positive integer, got %s" % n)
1317
+ x, a, b = limit
1318
+ dx = (b - a)/n
1319
+ k = Dummy('k', integer=True, positive=True)
1320
+ f = self.function
1321
+
1322
+ if method == "left":
1323
+ result = dx*Sum(f.subs(x, a + (k-1)*dx), (k, 1, n))
1324
+ elif method == "right":
1325
+ result = dx*Sum(f.subs(x, a + k*dx), (k, 1, n))
1326
+ elif method == "midpoint":
1327
+ result = dx*Sum(f.subs(x, a + k*dx - dx/2), (k, 1, n))
1328
+ elif method == "trapezoid":
1329
+ result = dx*((f.subs(x, a) + f.subs(x, b))/2 +
1330
+ Sum(f.subs(x, a + k*dx), (k, 1, n - 1)))
1331
+ else:
1332
+ raise ValueError("Unknown method %s" % method)
1333
+ return result.doit() if evaluate else result
1334
+
1335
+ def principal_value(self, **kwargs):
1336
+ """
1337
+ Compute the Cauchy Principal Value of the definite integral of a real function in the given interval
1338
+ on the real axis.
1339
+
1340
+ Explanation
1341
+ ===========
1342
+
1343
+ In mathematics, the Cauchy principal value, is a method for assigning values to certain improper
1344
+ integrals which would otherwise be undefined.
1345
+
1346
+ Examples
1347
+ ========
1348
+
1349
+ >>> from sympy import Integral, oo
1350
+ >>> from sympy.abc import x
1351
+ >>> Integral(x+1, (x, -oo, oo)).principal_value()
1352
+ oo
1353
+ >>> f = 1 / (x**3)
1354
+ >>> Integral(f, (x, -oo, oo)).principal_value()
1355
+ 0
1356
+ >>> Integral(f, (x, -10, 10)).principal_value()
1357
+ 0
1358
+ >>> Integral(f, (x, -10, oo)).principal_value() + Integral(f, (x, -oo, 10)).principal_value()
1359
+ 0
1360
+
1361
+ References
1362
+ ==========
1363
+
1364
+ .. [1] https://en.wikipedia.org/wiki/Cauchy_principal_value
1365
+ .. [2] https://mathworld.wolfram.com/CauchyPrincipalValue.html
1366
+ """
1367
+ if len(self.limits) != 1 or len(list(self.limits[0])) != 3:
1368
+ raise ValueError("You need to insert a variable, lower_limit, and upper_limit correctly to calculate "
1369
+ "cauchy's principal value")
1370
+ x, a, b = self.limits[0]
1371
+ if not (a.is_comparable and b.is_comparable and a <= b):
1372
+ raise ValueError("The lower_limit must be smaller than or equal to the upper_limit to calculate "
1373
+ "cauchy's principal value. Also, a and b need to be comparable.")
1374
+ if a == b:
1375
+ return S.Zero
1376
+
1377
+ from sympy.calculus.singularities import singularities
1378
+
1379
+ r = Dummy('r')
1380
+ f = self.function
1381
+ singularities_list = [s for s in singularities(f, x) if s.is_comparable and a <= s <= b]
1382
+ for i in singularities_list:
1383
+ if i in (a, b):
1384
+ raise ValueError(
1385
+ 'The principal value is not defined in the given interval due to singularity at %d.' % (i))
1386
+ F = integrate(f, x, **kwargs)
1387
+ if F.has(Integral):
1388
+ return self
1389
+ if a is -oo and b is oo:
1390
+ I = limit(F - F.subs(x, -x), x, oo)
1391
+ else:
1392
+ I = limit(F, x, b, '-') - limit(F, x, a, '+')
1393
+ for s in singularities_list:
1394
+ I += limit(((F.subs(x, s - r)) - F.subs(x, s + r)), r, 0, '+')
1395
+ return I
1396
+
1397
+
1398
+
1399
+ def integrate(*args, meijerg=None, conds='piecewise', risch=None, heurisch=None, manual=None, **kwargs):
1400
+ """integrate(f, var, ...)
1401
+
1402
+ .. deprecated:: 1.6
1403
+
1404
+ Using ``integrate()`` with :class:`~.Poly` is deprecated. Use
1405
+ :meth:`.Poly.integrate` instead. See :ref:`deprecated-integrate-poly`.
1406
+
1407
+ Explanation
1408
+ ===========
1409
+
1410
+ Compute definite or indefinite integral of one or more variables
1411
+ using Risch-Norman algorithm and table lookup. This procedure is
1412
+ able to handle elementary algebraic and transcendental functions
1413
+ and also a huge class of special functions, including Airy,
1414
+ Bessel, Whittaker and Lambert.
1415
+
1416
+ var can be:
1417
+
1418
+ - a symbol -- indefinite integration
1419
+ - a tuple (symbol, a) -- indefinite integration with result
1420
+ given with ``a`` replacing ``symbol``
1421
+ - a tuple (symbol, a, b) -- definite integration
1422
+
1423
+ Several variables can be specified, in which case the result is
1424
+ multiple integration. (If var is omitted and the integrand is
1425
+ univariate, the indefinite integral in that variable will be performed.)
1426
+
1427
+ Indefinite integrals are returned without terms that are independent
1428
+ of the integration variables. (see examples)
1429
+
1430
+ Definite improper integrals often entail delicate convergence
1431
+ conditions. Pass conds='piecewise', 'separate' or 'none' to have
1432
+ these returned, respectively, as a Piecewise function, as a separate
1433
+ result (i.e. result will be a tuple), or not at all (default is
1434
+ 'piecewise').
1435
+
1436
+ **Strategy**
1437
+
1438
+ SymPy uses various approaches to definite integration. One method is to
1439
+ find an antiderivative for the integrand, and then use the fundamental
1440
+ theorem of calculus. Various functions are implemented to integrate
1441
+ polynomial, rational and trigonometric functions, and integrands
1442
+ containing DiracDelta terms.
1443
+
1444
+ SymPy also implements the part of the Risch algorithm, which is a decision
1445
+ procedure for integrating elementary functions, i.e., the algorithm can
1446
+ either find an elementary antiderivative, or prove that one does not
1447
+ exist. There is also a (very successful, albeit somewhat slow) general
1448
+ implementation of the heuristic Risch algorithm. This algorithm will
1449
+ eventually be phased out as more of the full Risch algorithm is
1450
+ implemented. See the docstring of Integral._eval_integral() for more
1451
+ details on computing the antiderivative using algebraic methods.
1452
+
1453
+ The option risch=True can be used to use only the (full) Risch algorithm.
1454
+ This is useful if you want to know if an elementary function has an
1455
+ elementary antiderivative. If the indefinite Integral returned by this
1456
+ function is an instance of NonElementaryIntegral, that means that the
1457
+ Risch algorithm has proven that integral to be non-elementary. Note that
1458
+ by default, additional methods (such as the Meijer G method outlined
1459
+ below) are tried on these integrals, as they may be expressible in terms
1460
+ of special functions, so if you only care about elementary answers, use
1461
+ risch=True. Also note that an unevaluated Integral returned by this
1462
+ function is not necessarily a NonElementaryIntegral, even with risch=True,
1463
+ as it may just be an indication that the particular part of the Risch
1464
+ algorithm needed to integrate that function is not yet implemented.
1465
+
1466
+ Another family of strategies comes from re-writing the integrand in
1467
+ terms of so-called Meijer G-functions. Indefinite integrals of a
1468
+ single G-function can always be computed, and the definite integral
1469
+ of a product of two G-functions can be computed from zero to
1470
+ infinity. Various strategies are implemented to rewrite integrands
1471
+ as G-functions, and use this information to compute integrals (see
1472
+ the ``meijerint`` module).
1473
+
1474
+ The option manual=True can be used to use only an algorithm that tries
1475
+ to mimic integration by hand. This algorithm does not handle as many
1476
+ integrands as the other algorithms implemented but may return results in
1477
+ a more familiar form. The ``manualintegrate`` module has functions that
1478
+ return the steps used (see the module docstring for more information).
1479
+
1480
+ In general, the algebraic methods work best for computing
1481
+ antiderivatives of (possibly complicated) combinations of elementary
1482
+ functions. The G-function methods work best for computing definite
1483
+ integrals from zero to infinity of moderately complicated
1484
+ combinations of special functions, or indefinite integrals of very
1485
+ simple combinations of special functions.
1486
+
1487
+ The strategy employed by the integration code is as follows:
1488
+
1489
+ - If computing a definite integral, and both limits are real,
1490
+ and at least one limit is +- oo, try the G-function method of
1491
+ definite integration first.
1492
+
1493
+ - Try to find an antiderivative, using all available methods, ordered
1494
+ by performance (that is try fastest method first, slowest last; in
1495
+ particular polynomial integration is tried first, Meijer
1496
+ G-functions second to last, and heuristic Risch last).
1497
+
1498
+ - If still not successful, try G-functions irrespective of the
1499
+ limits.
1500
+
1501
+ The option meijerg=True, False, None can be used to, respectively:
1502
+ always use G-function methods and no others, never use G-function
1503
+ methods, or use all available methods (in order as described above).
1504
+ It defaults to None.
1505
+
1506
+ Examples
1507
+ ========
1508
+
1509
+ >>> from sympy import integrate, log, exp, oo
1510
+ >>> from sympy.abc import a, x, y
1511
+
1512
+ >>> integrate(x*y, x)
1513
+ x**2*y/2
1514
+
1515
+ >>> integrate(log(x), x)
1516
+ x*log(x) - x
1517
+
1518
+ >>> integrate(log(x), (x, 1, a))
1519
+ a*log(a) - a + 1
1520
+
1521
+ >>> integrate(x)
1522
+ x**2/2
1523
+
1524
+ Terms that are independent of x are dropped by indefinite integration:
1525
+
1526
+ >>> from sympy import sqrt
1527
+ >>> integrate(sqrt(1 + x), (x, 0, x))
1528
+ 2*(x + 1)**(3/2)/3 - 2/3
1529
+ >>> integrate(sqrt(1 + x), x)
1530
+ 2*(x + 1)**(3/2)/3
1531
+
1532
+ >>> integrate(x*y)
1533
+ Traceback (most recent call last):
1534
+ ...
1535
+ ValueError: specify integration variables to integrate x*y
1536
+
1537
+ Note that ``integrate(x)`` syntax is meant only for convenience
1538
+ in interactive sessions and should be avoided in library code.
1539
+
1540
+ >>> integrate(x**a*exp(-x), (x, 0, oo)) # same as conds='piecewise'
1541
+ Piecewise((gamma(a + 1), re(a) > -1),
1542
+ (Integral(x**a*exp(-x), (x, 0, oo)), True))
1543
+
1544
+ >>> integrate(x**a*exp(-x), (x, 0, oo), conds='none')
1545
+ gamma(a + 1)
1546
+
1547
+ >>> integrate(x**a*exp(-x), (x, 0, oo), conds='separate')
1548
+ (gamma(a + 1), re(a) > -1)
1549
+
1550
+ See Also
1551
+ ========
1552
+
1553
+ Integral, Integral.doit
1554
+
1555
+ """
1556
+ doit_flags = {
1557
+ 'deep': False,
1558
+ 'meijerg': meijerg,
1559
+ 'conds': conds,
1560
+ 'risch': risch,
1561
+ 'heurisch': heurisch,
1562
+ 'manual': manual
1563
+ }
1564
+ integral = Integral(*args, **kwargs)
1565
+
1566
+ if isinstance(integral, Integral):
1567
+ return integral.doit(**doit_flags)
1568
+ else:
1569
+ new_args = [a.doit(**doit_flags) if isinstance(a, Integral) else a
1570
+ for a in integral.args]
1571
+ return integral.func(*new_args)
1572
+
1573
+
1574
+ def line_integrate(field, curve, vars):
1575
+ """line_integrate(field, Curve, variables)
1576
+
1577
+ Compute the line integral.
1578
+
1579
+ Examples
1580
+ ========
1581
+
1582
+ >>> from sympy import Curve, line_integrate, E, ln
1583
+ >>> from sympy.abc import x, y, t
1584
+ >>> C = Curve([E**t + 1, E**t - 1], (t, 0, ln(2)))
1585
+ >>> line_integrate(x + y, C, [x, y])
1586
+ 3*sqrt(2)
1587
+
1588
+ See Also
1589
+ ========
1590
+
1591
+ sympy.integrals.integrals.integrate, Integral
1592
+ """
1593
+ from sympy.geometry import Curve
1594
+ F = sympify(field)
1595
+ if not F:
1596
+ raise ValueError(
1597
+ "Expecting function specifying field as first argument.")
1598
+ if not isinstance(curve, Curve):
1599
+ raise ValueError("Expecting Curve entity as second argument.")
1600
+ if not is_sequence(vars):
1601
+ raise ValueError("Expecting ordered iterable for variables.")
1602
+ if len(curve.functions) != len(vars):
1603
+ raise ValueError("Field variable size does not match curve dimension.")
1604
+
1605
+ if curve.parameter in vars:
1606
+ raise ValueError("Curve parameter clashes with field parameters.")
1607
+
1608
+ # Calculate derivatives for line parameter functions
1609
+ # F(r) -> F(r(t)) and finally F(r(t)*r'(t))
1610
+ Ft = F
1611
+ dldt = 0
1612
+ for i, var in enumerate(vars):
1613
+ _f = curve.functions[i]
1614
+ _dn = diff(_f, curve.parameter)
1615
+ # ...arc length
1616
+ dldt = dldt + (_dn * _dn)
1617
+ Ft = Ft.subs(var, _f)
1618
+ Ft = Ft * sqrt(dldt)
1619
+
1620
+ integral = Integral(Ft, curve.limits).doit(deep=False)
1621
+ return integral
1622
+
1623
+
1624
+ ### Property function dispatching ###
1625
+
1626
+ @shape.register(Integral)
1627
+ def _(expr):
1628
+ return shape(expr.function)
1629
+
1630
+ # Delayed imports
1631
+ from .deltafunctions import deltaintegrate
1632
+ from .meijerint import meijerint_definite, meijerint_indefinite, _debug
1633
+ from .trigonometry import trigintegrate
venv/lib/python3.10/site-packages/sympy/integrals/intpoly.py ADDED
@@ -0,0 +1,1302 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """
2
+ Module to implement integration of uni/bivariate polynomials over
3
+ 2D Polytopes and uni/bi/trivariate polynomials over 3D Polytopes.
4
+
5
+ Uses evaluation techniques as described in Chin et al. (2015) [1].
6
+
7
+
8
+ References
9
+ ===========
10
+
11
+ .. [1] Chin, Eric B., Jean B. Lasserre, and N. Sukumar. "Numerical integration
12
+ of homogeneous functions on convex and nonconvex polygons and polyhedra."
13
+ Computational Mechanics 56.6 (2015): 967-981
14
+
15
+ PDF link : http://dilbert.engr.ucdavis.edu/~suku/quadrature/cls-integration.pdf
16
+ """
17
+
18
+ from functools import cmp_to_key
19
+
20
+ from sympy.abc import x, y, z
21
+ from sympy.core import S, diff, Expr, Symbol
22
+ from sympy.core.sympify import _sympify
23
+ from sympy.geometry import Segment2D, Polygon, Point, Point2D
24
+ from sympy.polys.polytools import LC, gcd_list, degree_list, Poly
25
+ from sympy.simplify.simplify import nsimplify
26
+
27
+
28
+ def polytope_integrate(poly, expr=None, *, clockwise=False, max_degree=None):
29
+ """Integrates polynomials over 2/3-Polytopes.
30
+
31
+ Explanation
32
+ ===========
33
+
34
+ This function accepts the polytope in ``poly`` and the function in ``expr``
35
+ (uni/bi/trivariate polynomials are implemented) and returns
36
+ the exact integral of ``expr`` over ``poly``.
37
+
38
+ Parameters
39
+ ==========
40
+
41
+ poly : The input Polygon.
42
+
43
+ expr : The input polynomial.
44
+
45
+ clockwise : Binary value to sort input points of 2-Polytope clockwise.(Optional)
46
+
47
+ max_degree : The maximum degree of any monomial of the input polynomial.(Optional)
48
+
49
+ Examples
50
+ ========
51
+
52
+ >>> from sympy.abc import x, y
53
+ >>> from sympy import Point, Polygon
54
+ >>> from sympy.integrals.intpoly import polytope_integrate
55
+ >>> polygon = Polygon(Point(0, 0), Point(0, 1), Point(1, 1), Point(1, 0))
56
+ >>> polys = [1, x, y, x*y, x**2*y, x*y**2]
57
+ >>> expr = x*y
58
+ >>> polytope_integrate(polygon, expr)
59
+ 1/4
60
+ >>> polytope_integrate(polygon, polys, max_degree=3)
61
+ {1: 1, x: 1/2, y: 1/2, x*y: 1/4, x*y**2: 1/6, x**2*y: 1/6}
62
+ """
63
+ if clockwise:
64
+ if isinstance(poly, Polygon):
65
+ poly = Polygon(*point_sort(poly.vertices), evaluate=False)
66
+ else:
67
+ raise TypeError("clockwise=True works for only 2-Polytope"
68
+ "V-representation input")
69
+
70
+ if isinstance(poly, Polygon):
71
+ # For Vertex Representation(2D case)
72
+ hp_params = hyperplane_parameters(poly)
73
+ facets = poly.sides
74
+ elif len(poly[0]) == 2:
75
+ # For Hyperplane Representation(2D case)
76
+ plen = len(poly)
77
+ if len(poly[0][0]) == 2:
78
+ intersections = [intersection(poly[(i - 1) % plen], poly[i],
79
+ "plane2D")
80
+ for i in range(0, plen)]
81
+ hp_params = poly
82
+ lints = len(intersections)
83
+ facets = [Segment2D(intersections[i],
84
+ intersections[(i + 1) % lints])
85
+ for i in range(lints)]
86
+ else:
87
+ raise NotImplementedError("Integration for H-representation 3D"
88
+ "case not implemented yet.")
89
+ else:
90
+ # For Vertex Representation(3D case)
91
+ vertices = poly[0]
92
+ facets = poly[1:]
93
+ hp_params = hyperplane_parameters(facets, vertices)
94
+
95
+ if max_degree is None:
96
+ if expr is None:
97
+ raise TypeError('Input expression must be a valid SymPy expression')
98
+ return main_integrate3d(expr, facets, vertices, hp_params)
99
+
100
+ if max_degree is not None:
101
+ result = {}
102
+ if expr is not None:
103
+ f_expr = []
104
+ for e in expr:
105
+ _ = decompose(e)
106
+ if len(_) == 1 and not _.popitem()[0]:
107
+ f_expr.append(e)
108
+ elif Poly(e).total_degree() <= max_degree:
109
+ f_expr.append(e)
110
+ expr = f_expr
111
+
112
+ if not isinstance(expr, list) and expr is not None:
113
+ raise TypeError('Input polynomials must be list of expressions')
114
+
115
+ if len(hp_params[0][0]) == 3:
116
+ result_dict = main_integrate3d(0, facets, vertices, hp_params,
117
+ max_degree)
118
+ else:
119
+ result_dict = main_integrate(0, facets, hp_params, max_degree)
120
+
121
+ if expr is None:
122
+ return result_dict
123
+
124
+ for poly in expr:
125
+ poly = _sympify(poly)
126
+ if poly not in result:
127
+ if poly.is_zero:
128
+ result[S.Zero] = S.Zero
129
+ continue
130
+ integral_value = S.Zero
131
+ monoms = decompose(poly, separate=True)
132
+ for monom in monoms:
133
+ monom = nsimplify(monom)
134
+ coeff, m = strip(monom)
135
+ integral_value += result_dict[m] * coeff
136
+ result[poly] = integral_value
137
+ return result
138
+
139
+ if expr is None:
140
+ raise TypeError('Input expression must be a valid SymPy expression')
141
+
142
+ return main_integrate(expr, facets, hp_params)
143
+
144
+
145
+ def strip(monom):
146
+ if monom.is_zero:
147
+ return S.Zero, S.Zero
148
+ elif monom.is_number:
149
+ return monom, S.One
150
+ else:
151
+ coeff = LC(monom)
152
+ return coeff, monom / coeff
153
+
154
+ def _polynomial_integrate(polynomials, facets, hp_params):
155
+ dims = (x, y)
156
+ dim_length = len(dims)
157
+ integral_value = S.Zero
158
+ for deg in polynomials:
159
+ poly_contribute = S.Zero
160
+ facet_count = 0
161
+ for hp in hp_params:
162
+ value_over_boundary = integration_reduction(facets,
163
+ facet_count,
164
+ hp[0], hp[1],
165
+ polynomials[deg],
166
+ dims, deg)
167
+ poly_contribute += value_over_boundary * (hp[1] / norm(hp[0]))
168
+ facet_count += 1
169
+ poly_contribute /= (dim_length + deg)
170
+ integral_value += poly_contribute
171
+
172
+ return integral_value
173
+
174
+
175
+ def main_integrate3d(expr, facets, vertices, hp_params, max_degree=None):
176
+ """Function to translate the problem of integrating uni/bi/tri-variate
177
+ polynomials over a 3-Polytope to integrating over its faces.
178
+ This is done using Generalized Stokes' Theorem and Euler's Theorem.
179
+
180
+ Parameters
181
+ ==========
182
+
183
+ expr :
184
+ The input polynomial.
185
+ facets :
186
+ Faces of the 3-Polytope(expressed as indices of `vertices`).
187
+ vertices :
188
+ Vertices that constitute the Polytope.
189
+ hp_params :
190
+ Hyperplane Parameters of the facets.
191
+ max_degree : optional
192
+ Max degree of constituent monomial in given list of polynomial.
193
+
194
+ Examples
195
+ ========
196
+
197
+ >>> from sympy.integrals.intpoly import main_integrate3d, \
198
+ hyperplane_parameters
199
+ >>> cube = [[(0, 0, 0), (0, 0, 5), (0, 5, 0), (0, 5, 5), (5, 0, 0),\
200
+ (5, 0, 5), (5, 5, 0), (5, 5, 5)],\
201
+ [2, 6, 7, 3], [3, 7, 5, 1], [7, 6, 4, 5], [1, 5, 4, 0],\
202
+ [3, 1, 0, 2], [0, 4, 6, 2]]
203
+ >>> vertices = cube[0]
204
+ >>> faces = cube[1:]
205
+ >>> hp_params = hyperplane_parameters(faces, vertices)
206
+ >>> main_integrate3d(1, faces, vertices, hp_params)
207
+ -125
208
+ """
209
+ result = {}
210
+ dims = (x, y, z)
211
+ dim_length = len(dims)
212
+ if max_degree:
213
+ grad_terms = gradient_terms(max_degree, 3)
214
+ flat_list = [term for z_terms in grad_terms
215
+ for x_term in z_terms
216
+ for term in x_term]
217
+
218
+ for term in flat_list:
219
+ result[term[0]] = 0
220
+
221
+ for facet_count, hp in enumerate(hp_params):
222
+ a, b = hp[0], hp[1]
223
+ x0 = vertices[facets[facet_count][0]]
224
+
225
+ for i, monom in enumerate(flat_list):
226
+ # Every monomial is a tuple :
227
+ # (term, x_degree, y_degree, z_degree, value over boundary)
228
+ expr, x_d, y_d, z_d, z_index, y_index, x_index, _ = monom
229
+ degree = x_d + y_d + z_d
230
+ if b.is_zero:
231
+ value_over_face = S.Zero
232
+ else:
233
+ value_over_face = \
234
+ integration_reduction_dynamic(facets, facet_count, a,
235
+ b, expr, degree, dims,
236
+ x_index, y_index,
237
+ z_index, x0, grad_terms,
238
+ i, vertices, hp)
239
+ monom[7] = value_over_face
240
+ result[expr] += value_over_face * \
241
+ (b / norm(a)) / (dim_length + x_d + y_d + z_d)
242
+ return result
243
+ else:
244
+ integral_value = S.Zero
245
+ polynomials = decompose(expr)
246
+ for deg in polynomials:
247
+ poly_contribute = S.Zero
248
+ facet_count = 0
249
+ for i, facet in enumerate(facets):
250
+ hp = hp_params[i]
251
+ if hp[1].is_zero:
252
+ continue
253
+ pi = polygon_integrate(facet, hp, i, facets, vertices, expr, deg)
254
+ poly_contribute += pi *\
255
+ (hp[1] / norm(tuple(hp[0])))
256
+ facet_count += 1
257
+ poly_contribute /= (dim_length + deg)
258
+ integral_value += poly_contribute
259
+ return integral_value
260
+
261
+
262
+ def main_integrate(expr, facets, hp_params, max_degree=None):
263
+ """Function to translate the problem of integrating univariate/bivariate
264
+ polynomials over a 2-Polytope to integrating over its boundary facets.
265
+ This is done using Generalized Stokes's Theorem and Euler's Theorem.
266
+
267
+ Parameters
268
+ ==========
269
+
270
+ expr :
271
+ The input polynomial.
272
+ facets :
273
+ Facets(Line Segments) of the 2-Polytope.
274
+ hp_params :
275
+ Hyperplane Parameters of the facets.
276
+ max_degree : optional
277
+ The maximum degree of any monomial of the input polynomial.
278
+
279
+ >>> from sympy.abc import x, y
280
+ >>> from sympy.integrals.intpoly import main_integrate,\
281
+ hyperplane_parameters
282
+ >>> from sympy import Point, Polygon
283
+ >>> triangle = Polygon(Point(0, 3), Point(5, 3), Point(1, 1))
284
+ >>> facets = triangle.sides
285
+ >>> hp_params = hyperplane_parameters(triangle)
286
+ >>> main_integrate(x**2 + y**2, facets, hp_params)
287
+ 325/6
288
+ """
289
+ dims = (x, y)
290
+ dim_length = len(dims)
291
+ result = {}
292
+
293
+ if max_degree:
294
+ grad_terms = [[0, 0, 0, 0]] + gradient_terms(max_degree)
295
+
296
+ for facet_count, hp in enumerate(hp_params):
297
+ a, b = hp[0], hp[1]
298
+ x0 = facets[facet_count].points[0]
299
+
300
+ for i, monom in enumerate(grad_terms):
301
+ # Every monomial is a tuple :
302
+ # (term, x_degree, y_degree, value over boundary)
303
+ m, x_d, y_d, _ = monom
304
+ value = result.get(m, None)
305
+ degree = S.Zero
306
+ if b.is_zero:
307
+ value_over_boundary = S.Zero
308
+ else:
309
+ degree = x_d + y_d
310
+ value_over_boundary = \
311
+ integration_reduction_dynamic(facets, facet_count, a,
312
+ b, m, degree, dims, x_d,
313
+ y_d, max_degree, x0,
314
+ grad_terms, i)
315
+ monom[3] = value_over_boundary
316
+ if value is not None:
317
+ result[m] += value_over_boundary * \
318
+ (b / norm(a)) / (dim_length + degree)
319
+ else:
320
+ result[m] = value_over_boundary * \
321
+ (b / norm(a)) / (dim_length + degree)
322
+ return result
323
+ else:
324
+ if not isinstance(expr, list):
325
+ polynomials = decompose(expr)
326
+ return _polynomial_integrate(polynomials, facets, hp_params)
327
+ else:
328
+ return {e: _polynomial_integrate(decompose(e), facets, hp_params) for e in expr}
329
+
330
+
331
+ def polygon_integrate(facet, hp_param, index, facets, vertices, expr, degree):
332
+ """Helper function to integrate the input uni/bi/trivariate polynomial
333
+ over a certain face of the 3-Polytope.
334
+
335
+ Parameters
336
+ ==========
337
+
338
+ facet :
339
+ Particular face of the 3-Polytope over which ``expr`` is integrated.
340
+ index :
341
+ The index of ``facet`` in ``facets``.
342
+ facets :
343
+ Faces of the 3-Polytope(expressed as indices of `vertices`).
344
+ vertices :
345
+ Vertices that constitute the facet.
346
+ expr :
347
+ The input polynomial.
348
+ degree :
349
+ Degree of ``expr``.
350
+
351
+ Examples
352
+ ========
353
+
354
+ >>> from sympy.integrals.intpoly import polygon_integrate
355
+ >>> cube = [[(0, 0, 0), (0, 0, 5), (0, 5, 0), (0, 5, 5), (5, 0, 0),\
356
+ (5, 0, 5), (5, 5, 0), (5, 5, 5)],\
357
+ [2, 6, 7, 3], [3, 7, 5, 1], [7, 6, 4, 5], [1, 5, 4, 0],\
358
+ [3, 1, 0, 2], [0, 4, 6, 2]]
359
+ >>> facet = cube[1]
360
+ >>> facets = cube[1:]
361
+ >>> vertices = cube[0]
362
+ >>> polygon_integrate(facet, [(0, 1, 0), 5], 0, facets, vertices, 1, 0)
363
+ -25
364
+ """
365
+ expr = S(expr)
366
+ if expr.is_zero:
367
+ return S.Zero
368
+ result = S.Zero
369
+ x0 = vertices[facet[0]]
370
+ facet_len = len(facet)
371
+ for i, fac in enumerate(facet):
372
+ side = (vertices[fac], vertices[facet[(i + 1) % facet_len]])
373
+ result += distance_to_side(x0, side, hp_param[0]) *\
374
+ lineseg_integrate(facet, i, side, expr, degree)
375
+ if not expr.is_number:
376
+ expr = diff(expr, x) * x0[0] + diff(expr, y) * x0[1] +\
377
+ diff(expr, z) * x0[2]
378
+ result += polygon_integrate(facet, hp_param, index, facets, vertices,
379
+ expr, degree - 1)
380
+ result /= (degree + 2)
381
+ return result
382
+
383
+
384
+ def distance_to_side(point, line_seg, A):
385
+ """Helper function to compute the signed distance between given 3D point
386
+ and a line segment.
387
+
388
+ Parameters
389
+ ==========
390
+
391
+ point : 3D Point
392
+ line_seg : Line Segment
393
+
394
+ Examples
395
+ ========
396
+
397
+ >>> from sympy.integrals.intpoly import distance_to_side
398
+ >>> point = (0, 0, 0)
399
+ >>> distance_to_side(point, [(0, 0, 1), (0, 1, 0)], (1, 0, 0))
400
+ -sqrt(2)/2
401
+ """
402
+ x1, x2 = line_seg
403
+ rev_normal = [-1 * S(i)/norm(A) for i in A]
404
+ vector = [x2[i] - x1[i] for i in range(0, 3)]
405
+ vector = [vector[i]/norm(vector) for i in range(0, 3)]
406
+
407
+ n_side = cross_product((0, 0, 0), rev_normal, vector)
408
+ vectorx0 = [line_seg[0][i] - point[i] for i in range(0, 3)]
409
+ dot_product = sum([vectorx0[i] * n_side[i] for i in range(0, 3)])
410
+
411
+ return dot_product
412
+
413
+
414
+ def lineseg_integrate(polygon, index, line_seg, expr, degree):
415
+ """Helper function to compute the line integral of ``expr`` over ``line_seg``.
416
+
417
+ Parameters
418
+ ===========
419
+
420
+ polygon :
421
+ Face of a 3-Polytope.
422
+ index :
423
+ Index of line_seg in polygon.
424
+ line_seg :
425
+ Line Segment.
426
+
427
+ Examples
428
+ ========
429
+
430
+ >>> from sympy.integrals.intpoly import lineseg_integrate
431
+ >>> polygon = [(0, 5, 0), (5, 5, 0), (5, 5, 5), (0, 5, 5)]
432
+ >>> line_seg = [(0, 5, 0), (5, 5, 0)]
433
+ >>> lineseg_integrate(polygon, 0, line_seg, 1, 0)
434
+ 5
435
+ """
436
+ expr = _sympify(expr)
437
+ if expr.is_zero:
438
+ return S.Zero
439
+ result = S.Zero
440
+ x0 = line_seg[0]
441
+ distance = norm(tuple([line_seg[1][i] - line_seg[0][i] for i in
442
+ range(3)]))
443
+ if isinstance(expr, Expr):
444
+ expr_dict = {x: line_seg[1][0],
445
+ y: line_seg[1][1],
446
+ z: line_seg[1][2]}
447
+ result += distance * expr.subs(expr_dict)
448
+ else:
449
+ result += distance * expr
450
+
451
+ expr = diff(expr, x) * x0[0] + diff(expr, y) * x0[1] +\
452
+ diff(expr, z) * x0[2]
453
+
454
+ result += lineseg_integrate(polygon, index, line_seg, expr, degree - 1)
455
+ result /= (degree + 1)
456
+ return result
457
+
458
+
459
+ def integration_reduction(facets, index, a, b, expr, dims, degree):
460
+ """Helper method for main_integrate. Returns the value of the input
461
+ expression evaluated over the polytope facet referenced by a given index.
462
+
463
+ Parameters
464
+ ===========
465
+
466
+ facets :
467
+ List of facets of the polytope.
468
+ index :
469
+ Index referencing the facet to integrate the expression over.
470
+ a :
471
+ Hyperplane parameter denoting direction.
472
+ b :
473
+ Hyperplane parameter denoting distance.
474
+ expr :
475
+ The expression to integrate over the facet.
476
+ dims :
477
+ List of symbols denoting axes.
478
+ degree :
479
+ Degree of the homogeneous polynomial.
480
+
481
+ Examples
482
+ ========
483
+
484
+ >>> from sympy.abc import x, y
485
+ >>> from sympy.integrals.intpoly import integration_reduction,\
486
+ hyperplane_parameters
487
+ >>> from sympy import Point, Polygon
488
+ >>> triangle = Polygon(Point(0, 3), Point(5, 3), Point(1, 1))
489
+ >>> facets = triangle.sides
490
+ >>> a, b = hyperplane_parameters(triangle)[0]
491
+ >>> integration_reduction(facets, 0, a, b, 1, (x, y), 0)
492
+ 5
493
+ """
494
+ expr = _sympify(expr)
495
+ if expr.is_zero:
496
+ return expr
497
+
498
+ value = S.Zero
499
+ x0 = facets[index].points[0]
500
+ m = len(facets)
501
+ gens = (x, y)
502
+
503
+ inner_product = diff(expr, gens[0]) * x0[0] + diff(expr, gens[1]) * x0[1]
504
+
505
+ if inner_product != 0:
506
+ value += integration_reduction(facets, index, a, b,
507
+ inner_product, dims, degree - 1)
508
+
509
+ value += left_integral2D(m, index, facets, x0, expr, gens)
510
+
511
+ return value/(len(dims) + degree - 1)
512
+
513
+
514
+ def left_integral2D(m, index, facets, x0, expr, gens):
515
+ """Computes the left integral of Eq 10 in Chin et al.
516
+ For the 2D case, the integral is just an evaluation of the polynomial
517
+ at the intersection of two facets which is multiplied by the distance
518
+ between the first point of facet and that intersection.
519
+
520
+ Parameters
521
+ ==========
522
+
523
+ m :
524
+ No. of hyperplanes.
525
+ index :
526
+ Index of facet to find intersections with.
527
+ facets :
528
+ List of facets(Line Segments in 2D case).
529
+ x0 :
530
+ First point on facet referenced by index.
531
+ expr :
532
+ Input polynomial
533
+ gens :
534
+ Generators which generate the polynomial
535
+
536
+ Examples
537
+ ========
538
+
539
+ >>> from sympy.abc import x, y
540
+ >>> from sympy.integrals.intpoly import left_integral2D
541
+ >>> from sympy import Point, Polygon
542
+ >>> triangle = Polygon(Point(0, 3), Point(5, 3), Point(1, 1))
543
+ >>> facets = triangle.sides
544
+ >>> left_integral2D(3, 0, facets, facets[0].points[0], 1, (x, y))
545
+ 5
546
+ """
547
+ value = S.Zero
548
+ for j in range(m):
549
+ intersect = ()
550
+ if j in ((index - 1) % m, (index + 1) % m):
551
+ intersect = intersection(facets[index], facets[j], "segment2D")
552
+ if intersect:
553
+ distance_origin = norm(tuple(map(lambda x, y: x - y,
554
+ intersect, x0)))
555
+ if is_vertex(intersect):
556
+ if isinstance(expr, Expr):
557
+ if len(gens) == 3:
558
+ expr_dict = {gens[0]: intersect[0],
559
+ gens[1]: intersect[1],
560
+ gens[2]: intersect[2]}
561
+ else:
562
+ expr_dict = {gens[0]: intersect[0],
563
+ gens[1]: intersect[1]}
564
+ value += distance_origin * expr.subs(expr_dict)
565
+ else:
566
+ value += distance_origin * expr
567
+ return value
568
+
569
+
570
+ def integration_reduction_dynamic(facets, index, a, b, expr, degree, dims,
571
+ x_index, y_index, max_index, x0,
572
+ monomial_values, monom_index, vertices=None,
573
+ hp_param=None):
574
+ """The same integration_reduction function which uses a dynamic
575
+ programming approach to compute terms by using the values of the integral
576
+ of previously computed terms.
577
+
578
+ Parameters
579
+ ==========
580
+
581
+ facets :
582
+ Facets of the Polytope.
583
+ index :
584
+ Index of facet to find intersections with.(Used in left_integral()).
585
+ a, b :
586
+ Hyperplane parameters.
587
+ expr :
588
+ Input monomial.
589
+ degree :
590
+ Total degree of ``expr``.
591
+ dims :
592
+ Tuple denoting axes variables.
593
+ x_index :
594
+ Exponent of 'x' in ``expr``.
595
+ y_index :
596
+ Exponent of 'y' in ``expr``.
597
+ max_index :
598
+ Maximum exponent of any monomial in ``monomial_values``.
599
+ x0 :
600
+ First point on ``facets[index]``.
601
+ monomial_values :
602
+ List of monomial values constituting the polynomial.
603
+ monom_index :
604
+ Index of monomial whose integration is being found.
605
+ vertices : optional
606
+ Coordinates of vertices constituting the 3-Polytope.
607
+ hp_param : optional
608
+ Hyperplane Parameter of the face of the facets[index].
609
+
610
+ Examples
611
+ ========
612
+
613
+ >>> from sympy.abc import x, y
614
+ >>> from sympy.integrals.intpoly import (integration_reduction_dynamic, \
615
+ hyperplane_parameters)
616
+ >>> from sympy import Point, Polygon
617
+ >>> triangle = Polygon(Point(0, 3), Point(5, 3), Point(1, 1))
618
+ >>> facets = triangle.sides
619
+ >>> a, b = hyperplane_parameters(triangle)[0]
620
+ >>> x0 = facets[0].points[0]
621
+ >>> monomial_values = [[0, 0, 0, 0], [1, 0, 0, 5],\
622
+ [y, 0, 1, 15], [x, 1, 0, None]]
623
+ >>> integration_reduction_dynamic(facets, 0, a, b, x, 1, (x, y), 1, 0, 1,\
624
+ x0, monomial_values, 3)
625
+ 25/2
626
+ """
627
+ value = S.Zero
628
+ m = len(facets)
629
+
630
+ if expr == S.Zero:
631
+ return expr
632
+
633
+ if len(dims) == 2:
634
+ if not expr.is_number:
635
+ _, x_degree, y_degree, _ = monomial_values[monom_index]
636
+ x_index = monom_index - max_index + \
637
+ x_index - 2 if x_degree > 0 else 0
638
+ y_index = monom_index - 1 if y_degree > 0 else 0
639
+ x_value, y_value =\
640
+ monomial_values[x_index][3], monomial_values[y_index][3]
641
+
642
+ value += x_degree * x_value * x0[0] + y_degree * y_value * x0[1]
643
+
644
+ value += left_integral2D(m, index, facets, x0, expr, dims)
645
+ else:
646
+ # For 3D use case the max_index contains the z_degree of the term
647
+ z_index = max_index
648
+ if not expr.is_number:
649
+ x_degree, y_degree, z_degree = y_index,\
650
+ z_index - x_index - y_index, x_index
651
+ x_value = monomial_values[z_index - 1][y_index - 1][x_index][7]\
652
+ if x_degree > 0 else 0
653
+ y_value = monomial_values[z_index - 1][y_index][x_index][7]\
654
+ if y_degree > 0 else 0
655
+ z_value = monomial_values[z_index - 1][y_index][x_index - 1][7]\
656
+ if z_degree > 0 else 0
657
+
658
+ value += x_degree * x_value * x0[0] + y_degree * y_value * x0[1] \
659
+ + z_degree * z_value * x0[2]
660
+
661
+ value += left_integral3D(facets, index, expr,
662
+ vertices, hp_param, degree)
663
+ return value / (len(dims) + degree - 1)
664
+
665
+
666
+ def left_integral3D(facets, index, expr, vertices, hp_param, degree):
667
+ """Computes the left integral of Eq 10 in Chin et al.
668
+
669
+ Explanation
670
+ ===========
671
+
672
+ For the 3D case, this is the sum of the integral values over constituting
673
+ line segments of the face (which is accessed by facets[index]) multiplied
674
+ by the distance between the first point of facet and that line segment.
675
+
676
+ Parameters
677
+ ==========
678
+
679
+ facets :
680
+ List of faces of the 3-Polytope.
681
+ index :
682
+ Index of face over which integral is to be calculated.
683
+ expr :
684
+ Input polynomial.
685
+ vertices :
686
+ List of vertices that constitute the 3-Polytope.
687
+ hp_param :
688
+ The hyperplane parameters of the face.
689
+ degree :
690
+ Degree of the ``expr``.
691
+
692
+ Examples
693
+ ========
694
+
695
+ >>> from sympy.integrals.intpoly import left_integral3D
696
+ >>> cube = [[(0, 0, 0), (0, 0, 5), (0, 5, 0), (0, 5, 5), (5, 0, 0),\
697
+ (5, 0, 5), (5, 5, 0), (5, 5, 5)],\
698
+ [2, 6, 7, 3], [3, 7, 5, 1], [7, 6, 4, 5], [1, 5, 4, 0],\
699
+ [3, 1, 0, 2], [0, 4, 6, 2]]
700
+ >>> facets = cube[1:]
701
+ >>> vertices = cube[0]
702
+ >>> left_integral3D(facets, 3, 1, vertices, ([0, -1, 0], -5), 0)
703
+ -50
704
+ """
705
+ value = S.Zero
706
+ facet = facets[index]
707
+ x0 = vertices[facet[0]]
708
+ facet_len = len(facet)
709
+ for i, fac in enumerate(facet):
710
+ side = (vertices[fac], vertices[facet[(i + 1) % facet_len]])
711
+ value += distance_to_side(x0, side, hp_param[0]) * \
712
+ lineseg_integrate(facet, i, side, expr, degree)
713
+ return value
714
+
715
+
716
+ def gradient_terms(binomial_power=0, no_of_gens=2):
717
+ """Returns a list of all the possible monomials between
718
+ 0 and y**binomial_power for 2D case and z**binomial_power
719
+ for 3D case.
720
+
721
+ Parameters
722
+ ==========
723
+
724
+ binomial_power :
725
+ Power upto which terms are generated.
726
+ no_of_gens :
727
+ Denotes whether terms are being generated for 2D or 3D case.
728
+
729
+ Examples
730
+ ========
731
+
732
+ >>> from sympy.integrals.intpoly import gradient_terms
733
+ >>> gradient_terms(2)
734
+ [[1, 0, 0, 0], [y, 0, 1, 0], [y**2, 0, 2, 0], [x, 1, 0, 0],
735
+ [x*y, 1, 1, 0], [x**2, 2, 0, 0]]
736
+ >>> gradient_terms(2, 3)
737
+ [[[[1, 0, 0, 0, 0, 0, 0, 0]]], [[[y, 0, 1, 0, 1, 0, 0, 0],
738
+ [z, 0, 0, 1, 1, 0, 1, 0]], [[x, 1, 0, 0, 1, 1, 0, 0]]],
739
+ [[[y**2, 0, 2, 0, 2, 0, 0, 0], [y*z, 0, 1, 1, 2, 0, 1, 0],
740
+ [z**2, 0, 0, 2, 2, 0, 2, 0]], [[x*y, 1, 1, 0, 2, 1, 0, 0],
741
+ [x*z, 1, 0, 1, 2, 1, 1, 0]], [[x**2, 2, 0, 0, 2, 2, 0, 0]]]]
742
+ """
743
+ if no_of_gens == 2:
744
+ count = 0
745
+ terms = [None] * int((binomial_power ** 2 + 3 * binomial_power + 2) / 2)
746
+ for x_count in range(0, binomial_power + 1):
747
+ for y_count in range(0, binomial_power - x_count + 1):
748
+ terms[count] = [x**x_count*y**y_count,
749
+ x_count, y_count, 0]
750
+ count += 1
751
+ else:
752
+ terms = [[[[x ** x_count * y ** y_count *
753
+ z ** (z_count - y_count - x_count),
754
+ x_count, y_count, z_count - y_count - x_count,
755
+ z_count, x_count, z_count - y_count - x_count, 0]
756
+ for y_count in range(z_count - x_count, -1, -1)]
757
+ for x_count in range(0, z_count + 1)]
758
+ for z_count in range(0, binomial_power + 1)]
759
+ return terms
760
+
761
+
762
+ def hyperplane_parameters(poly, vertices=None):
763
+ """A helper function to return the hyperplane parameters
764
+ of which the facets of the polytope are a part of.
765
+
766
+ Parameters
767
+ ==========
768
+
769
+ poly :
770
+ The input 2/3-Polytope.
771
+ vertices :
772
+ Vertex indices of 3-Polytope.
773
+
774
+ Examples
775
+ ========
776
+
777
+ >>> from sympy import Point, Polygon
778
+ >>> from sympy.integrals.intpoly import hyperplane_parameters
779
+ >>> hyperplane_parameters(Polygon(Point(0, 3), Point(5, 3), Point(1, 1)))
780
+ [((0, 1), 3), ((1, -2), -1), ((-2, -1), -3)]
781
+ >>> cube = [[(0, 0, 0), (0, 0, 5), (0, 5, 0), (0, 5, 5), (5, 0, 0),\
782
+ (5, 0, 5), (5, 5, 0), (5, 5, 5)],\
783
+ [2, 6, 7, 3], [3, 7, 5, 1], [7, 6, 4, 5], [1, 5, 4, 0],\
784
+ [3, 1, 0, 2], [0, 4, 6, 2]]
785
+ >>> hyperplane_parameters(cube[1:], cube[0])
786
+ [([0, -1, 0], -5), ([0, 0, -1], -5), ([-1, 0, 0], -5),
787
+ ([0, 1, 0], 0), ([1, 0, 0], 0), ([0, 0, 1], 0)]
788
+ """
789
+ if isinstance(poly, Polygon):
790
+ vertices = list(poly.vertices) + [poly.vertices[0]] # Close the polygon
791
+ params = [None] * (len(vertices) - 1)
792
+
793
+ for i in range(len(vertices) - 1):
794
+ v1 = vertices[i]
795
+ v2 = vertices[i + 1]
796
+
797
+ a1 = v1[1] - v2[1]
798
+ a2 = v2[0] - v1[0]
799
+ b = v2[0] * v1[1] - v2[1] * v1[0]
800
+
801
+ factor = gcd_list([a1, a2, b])
802
+
803
+ b = S(b) / factor
804
+ a = (S(a1) / factor, S(a2) / factor)
805
+ params[i] = (a, b)
806
+ else:
807
+ params = [None] * len(poly)
808
+ for i, polygon in enumerate(poly):
809
+ v1, v2, v3 = [vertices[vertex] for vertex in polygon[:3]]
810
+ normal = cross_product(v1, v2, v3)
811
+ b = sum([normal[j] * v1[j] for j in range(0, 3)])
812
+ fac = gcd_list(normal)
813
+ if fac.is_zero:
814
+ fac = 1
815
+ normal = [j / fac for j in normal]
816
+ b = b / fac
817
+ params[i] = (normal, b)
818
+ return params
819
+
820
+
821
+ def cross_product(v1, v2, v3):
822
+ """Returns the cross-product of vectors (v2 - v1) and (v3 - v1)
823
+ That is : (v2 - v1) X (v3 - v1)
824
+ """
825
+ v2 = [v2[j] - v1[j] for j in range(0, 3)]
826
+ v3 = [v3[j] - v1[j] for j in range(0, 3)]
827
+ return [v3[2] * v2[1] - v3[1] * v2[2],
828
+ v3[0] * v2[2] - v3[2] * v2[0],
829
+ v3[1] * v2[0] - v3[0] * v2[1]]
830
+
831
+
832
+ def best_origin(a, b, lineseg, expr):
833
+ """Helper method for polytope_integrate. Currently not used in the main
834
+ algorithm.
835
+
836
+ Explanation
837
+ ===========
838
+
839
+ Returns a point on the lineseg whose vector inner product with the
840
+ divergence of `expr` yields an expression with the least maximum
841
+ total power.
842
+
843
+ Parameters
844
+ ==========
845
+
846
+ a :
847
+ Hyperplane parameter denoting direction.
848
+ b :
849
+ Hyperplane parameter denoting distance.
850
+ lineseg :
851
+ Line segment on which to find the origin.
852
+ expr :
853
+ The expression which determines the best point.
854
+
855
+ Algorithm(currently works only for 2D use case)
856
+ ===============================================
857
+
858
+ 1 > Firstly, check for edge cases. Here that would refer to vertical
859
+ or horizontal lines.
860
+
861
+ 2 > If input expression is a polynomial containing more than one generator
862
+ then find out the total power of each of the generators.
863
+
864
+ x**2 + 3 + x*y + x**4*y**5 ---> {x: 7, y: 6}
865
+
866
+ If expression is a constant value then pick the first boundary point
867
+ of the line segment.
868
+
869
+ 3 > First check if a point exists on the line segment where the value of
870
+ the highest power generator becomes 0. If not check if the value of
871
+ the next highest becomes 0. If none becomes 0 within line segment
872
+ constraints then pick the first boundary point of the line segment.
873
+ Actually, any point lying on the segment can be picked as best origin
874
+ in the last case.
875
+
876
+ Examples
877
+ ========
878
+
879
+ >>> from sympy.integrals.intpoly import best_origin
880
+ >>> from sympy.abc import x, y
881
+ >>> from sympy import Point, Segment2D
882
+ >>> l = Segment2D(Point(0, 3), Point(1, 1))
883
+ >>> expr = x**3*y**7
884
+ >>> best_origin((2, 1), 3, l, expr)
885
+ (0, 3.0)
886
+ """
887
+ a1, b1 = lineseg.points[0]
888
+
889
+ def x_axis_cut(ls):
890
+ """Returns the point where the input line segment
891
+ intersects the x-axis.
892
+
893
+ Parameters
894
+ ==========
895
+
896
+ ls :
897
+ Line segment
898
+ """
899
+ p, q = ls.points
900
+ if p.y.is_zero:
901
+ return tuple(p)
902
+ elif q.y.is_zero:
903
+ return tuple(q)
904
+ elif p.y/q.y < S.Zero:
905
+ return p.y * (p.x - q.x)/(q.y - p.y) + p.x, S.Zero
906
+ else:
907
+ return ()
908
+
909
+ def y_axis_cut(ls):
910
+ """Returns the point where the input line segment
911
+ intersects the y-axis.
912
+
913
+ Parameters
914
+ ==========
915
+
916
+ ls :
917
+ Line segment
918
+ """
919
+ p, q = ls.points
920
+ if p.x.is_zero:
921
+ return tuple(p)
922
+ elif q.x.is_zero:
923
+ return tuple(q)
924
+ elif p.x/q.x < S.Zero:
925
+ return S.Zero, p.x * (p.y - q.y)/(q.x - p.x) + p.y
926
+ else:
927
+ return ()
928
+
929
+ gens = (x, y)
930
+ power_gens = {}
931
+
932
+ for i in gens:
933
+ power_gens[i] = S.Zero
934
+
935
+ if len(gens) > 1:
936
+ # Special case for vertical and horizontal lines
937
+ if len(gens) == 2:
938
+ if a[0] == 0:
939
+ if y_axis_cut(lineseg):
940
+ return S.Zero, b/a[1]
941
+ else:
942
+ return a1, b1
943
+ elif a[1] == 0:
944
+ if x_axis_cut(lineseg):
945
+ return b/a[0], S.Zero
946
+ else:
947
+ return a1, b1
948
+
949
+ if isinstance(expr, Expr): # Find the sum total of power of each
950
+ if expr.is_Add: # generator and store in a dictionary.
951
+ for monomial in expr.args:
952
+ if monomial.is_Pow:
953
+ if monomial.args[0] in gens:
954
+ power_gens[monomial.args[0]] += monomial.args[1]
955
+ else:
956
+ for univariate in monomial.args:
957
+ term_type = len(univariate.args)
958
+ if term_type == 0 and univariate in gens:
959
+ power_gens[univariate] += 1
960
+ elif term_type == 2 and univariate.args[0] in gens:
961
+ power_gens[univariate.args[0]] +=\
962
+ univariate.args[1]
963
+ elif expr.is_Mul:
964
+ for term in expr.args:
965
+ term_type = len(term.args)
966
+ if term_type == 0 and term in gens:
967
+ power_gens[term] += 1
968
+ elif term_type == 2 and term.args[0] in gens:
969
+ power_gens[term.args[0]] += term.args[1]
970
+ elif expr.is_Pow:
971
+ power_gens[expr.args[0]] = expr.args[1]
972
+ elif expr.is_Symbol:
973
+ power_gens[expr] += 1
974
+ else: # If `expr` is a constant take first vertex of the line segment.
975
+ return a1, b1
976
+
977
+ # TODO : This part is quite hacky. Should be made more robust with
978
+ # TODO : respect to symbol names and scalable w.r.t higher dimensions.
979
+ power_gens = sorted(power_gens.items(), key=lambda k: str(k[0]))
980
+ if power_gens[0][1] >= power_gens[1][1]:
981
+ if y_axis_cut(lineseg):
982
+ x0 = (S.Zero, b / a[1])
983
+ elif x_axis_cut(lineseg):
984
+ x0 = (b / a[0], S.Zero)
985
+ else:
986
+ x0 = (a1, b1)
987
+ else:
988
+ if x_axis_cut(lineseg):
989
+ x0 = (b/a[0], S.Zero)
990
+ elif y_axis_cut(lineseg):
991
+ x0 = (S.Zero, b/a[1])
992
+ else:
993
+ x0 = (a1, b1)
994
+ else:
995
+ x0 = (b/a[0])
996
+ return x0
997
+
998
+
999
+ def decompose(expr, separate=False):
1000
+ """Decomposes an input polynomial into homogeneous ones of
1001
+ smaller or equal degree.
1002
+
1003
+ Explanation
1004
+ ===========
1005
+
1006
+ Returns a dictionary with keys as the degree of the smaller
1007
+ constituting polynomials. Values are the constituting polynomials.
1008
+
1009
+ Parameters
1010
+ ==========
1011
+
1012
+ expr : Expr
1013
+ Polynomial(SymPy expression).
1014
+ separate : bool
1015
+ If True then simply return a list of the constituent monomials
1016
+ If not then break up the polynomial into constituent homogeneous
1017
+ polynomials.
1018
+
1019
+ Examples
1020
+ ========
1021
+
1022
+ >>> from sympy.abc import x, y
1023
+ >>> from sympy.integrals.intpoly import decompose
1024
+ >>> decompose(x**2 + x*y + x + y + x**3*y**2 + y**5)
1025
+ {1: x + y, 2: x**2 + x*y, 5: x**3*y**2 + y**5}
1026
+ >>> decompose(x**2 + x*y + x + y + x**3*y**2 + y**5, True)
1027
+ {x, x**2, y, y**5, x*y, x**3*y**2}
1028
+ """
1029
+ poly_dict = {}
1030
+
1031
+ if isinstance(expr, Expr) and not expr.is_number:
1032
+ if expr.is_Symbol:
1033
+ poly_dict[1] = expr
1034
+ elif expr.is_Add:
1035
+ symbols = expr.atoms(Symbol)
1036
+ degrees = [(sum(degree_list(monom, *symbols)), monom)
1037
+ for monom in expr.args]
1038
+ if separate:
1039
+ return {monom[1] for monom in degrees}
1040
+ else:
1041
+ for monom in degrees:
1042
+ degree, term = monom
1043
+ if poly_dict.get(degree):
1044
+ poly_dict[degree] += term
1045
+ else:
1046
+ poly_dict[degree] = term
1047
+ elif expr.is_Pow:
1048
+ _, degree = expr.args
1049
+ poly_dict[degree] = expr
1050
+ else: # Now expr can only be of `Mul` type
1051
+ degree = 0
1052
+ for term in expr.args:
1053
+ term_type = len(term.args)
1054
+ if term_type == 0 and term.is_Symbol:
1055
+ degree += 1
1056
+ elif term_type == 2:
1057
+ degree += term.args[1]
1058
+ poly_dict[degree] = expr
1059
+ else:
1060
+ poly_dict[0] = expr
1061
+
1062
+ if separate:
1063
+ return set(poly_dict.values())
1064
+ return poly_dict
1065
+
1066
+
1067
+ def point_sort(poly, normal=None, clockwise=True):
1068
+ """Returns the same polygon with points sorted in clockwise or
1069
+ anti-clockwise order.
1070
+
1071
+ Note that it's necessary for input points to be sorted in some order
1072
+ (clockwise or anti-clockwise) for the integration algorithm to work.
1073
+ As a convention algorithm has been implemented keeping clockwise
1074
+ orientation in mind.
1075
+
1076
+ Parameters
1077
+ ==========
1078
+
1079
+ poly:
1080
+ 2D or 3D Polygon.
1081
+ normal : optional
1082
+ The normal of the plane which the 3-Polytope is a part of.
1083
+ clockwise : bool, optional
1084
+ Returns points sorted in clockwise order if True and
1085
+ anti-clockwise if False.
1086
+
1087
+ Examples
1088
+ ========
1089
+
1090
+ >>> from sympy.integrals.intpoly import point_sort
1091
+ >>> from sympy import Point
1092
+ >>> point_sort([Point(0, 0), Point(1, 0), Point(1, 1)])
1093
+ [Point2D(1, 1), Point2D(1, 0), Point2D(0, 0)]
1094
+ """
1095
+ pts = poly.vertices if isinstance(poly, Polygon) else poly
1096
+ n = len(pts)
1097
+ if n < 2:
1098
+ return list(pts)
1099
+
1100
+ order = S.One if clockwise else S.NegativeOne
1101
+ dim = len(pts[0])
1102
+ if dim == 2:
1103
+ center = Point(sum((vertex.x for vertex in pts)) / n,
1104
+ sum((vertex.y for vertex in pts)) / n)
1105
+ else:
1106
+ center = Point(sum((vertex.x for vertex in pts)) / n,
1107
+ sum((vertex.y for vertex in pts)) / n,
1108
+ sum((vertex.z for vertex in pts)) / n)
1109
+
1110
+ def compare(a, b):
1111
+ if a.x - center.x >= S.Zero and b.x - center.x < S.Zero:
1112
+ return -order
1113
+ elif a.x - center.x < 0 and b.x - center.x >= 0:
1114
+ return order
1115
+ elif a.x - center.x == 0 and b.x - center.x == 0:
1116
+ if a.y - center.y >= 0 or b.y - center.y >= 0:
1117
+ return -order if a.y > b.y else order
1118
+ return -order if b.y > a.y else order
1119
+
1120
+ det = (a.x - center.x) * (b.y - center.y) -\
1121
+ (b.x - center.x) * (a.y - center.y)
1122
+ if det < 0:
1123
+ return -order
1124
+ elif det > 0:
1125
+ return order
1126
+
1127
+ first = (a.x - center.x) * (a.x - center.x) +\
1128
+ (a.y - center.y) * (a.y - center.y)
1129
+ second = (b.x - center.x) * (b.x - center.x) +\
1130
+ (b.y - center.y) * (b.y - center.y)
1131
+ return -order if first > second else order
1132
+
1133
+ def compare3d(a, b):
1134
+ det = cross_product(center, a, b)
1135
+ dot_product = sum([det[i] * normal[i] for i in range(0, 3)])
1136
+ if dot_product < 0:
1137
+ return -order
1138
+ elif dot_product > 0:
1139
+ return order
1140
+
1141
+ return sorted(pts, key=cmp_to_key(compare if dim==2 else compare3d))
1142
+
1143
+
1144
+ def norm(point):
1145
+ """Returns the Euclidean norm of a point from origin.
1146
+
1147
+ Parameters
1148
+ ==========
1149
+
1150
+ point:
1151
+ This denotes a point in the dimension_al spac_e.
1152
+
1153
+ Examples
1154
+ ========
1155
+
1156
+ >>> from sympy.integrals.intpoly import norm
1157
+ >>> from sympy import Point
1158
+ >>> norm(Point(2, 7))
1159
+ sqrt(53)
1160
+ """
1161
+ half = S.Half
1162
+ if isinstance(point, (list, tuple)):
1163
+ return sum([coord ** 2 for coord in point]) ** half
1164
+ elif isinstance(point, Point):
1165
+ if isinstance(point, Point2D):
1166
+ return (point.x ** 2 + point.y ** 2) ** half
1167
+ else:
1168
+ return (point.x ** 2 + point.y ** 2 + point.z) ** half
1169
+ elif isinstance(point, dict):
1170
+ return sum(i**2 for i in point.values()) ** half
1171
+
1172
+
1173
+ def intersection(geom_1, geom_2, intersection_type):
1174
+ """Returns intersection between geometric objects.
1175
+
1176
+ Explanation
1177
+ ===========
1178
+
1179
+ Note that this function is meant for use in integration_reduction and
1180
+ at that point in the calling function the lines denoted by the segments
1181
+ surely intersect within segment boundaries. Coincident lines are taken
1182
+ to be non-intersecting. Also, the hyperplane intersection for 2D case is
1183
+ also implemented.
1184
+
1185
+ Parameters
1186
+ ==========
1187
+
1188
+ geom_1, geom_2:
1189
+ The input line segments.
1190
+
1191
+ Examples
1192
+ ========
1193
+
1194
+ >>> from sympy.integrals.intpoly import intersection
1195
+ >>> from sympy import Point, Segment2D
1196
+ >>> l1 = Segment2D(Point(1, 1), Point(3, 5))
1197
+ >>> l2 = Segment2D(Point(2, 0), Point(2, 5))
1198
+ >>> intersection(l1, l2, "segment2D")
1199
+ (2, 3)
1200
+ >>> p1 = ((-1, 0), 0)
1201
+ >>> p2 = ((0, 1), 1)
1202
+ >>> intersection(p1, p2, "plane2D")
1203
+ (0, 1)
1204
+ """
1205
+ if intersection_type[:-2] == "segment":
1206
+ if intersection_type == "segment2D":
1207
+ x1, y1 = geom_1.points[0]
1208
+ x2, y2 = geom_1.points[1]
1209
+ x3, y3 = geom_2.points[0]
1210
+ x4, y4 = geom_2.points[1]
1211
+ elif intersection_type == "segment3D":
1212
+ x1, y1, z1 = geom_1.points[0]
1213
+ x2, y2, z2 = geom_1.points[1]
1214
+ x3, y3, z3 = geom_2.points[0]
1215
+ x4, y4, z4 = geom_2.points[1]
1216
+
1217
+ denom = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4)
1218
+ if denom:
1219
+ t1 = x1 * y2 - y1 * x2
1220
+ t2 = x3 * y4 - x4 * y3
1221
+ return (S(t1 * (x3 - x4) - t2 * (x1 - x2)) / denom,
1222
+ S(t1 * (y3 - y4) - t2 * (y1 - y2)) / denom)
1223
+ if intersection_type[:-2] == "plane":
1224
+ if intersection_type == "plane2D": # Intersection of hyperplanes
1225
+ a1x, a1y = geom_1[0]
1226
+ a2x, a2y = geom_2[0]
1227
+ b1, b2 = geom_1[1], geom_2[1]
1228
+
1229
+ denom = a1x * a2y - a2x * a1y
1230
+ if denom:
1231
+ return (S(b1 * a2y - b2 * a1y) / denom,
1232
+ S(b2 * a1x - b1 * a2x) / denom)
1233
+
1234
+
1235
+ def is_vertex(ent):
1236
+ """If the input entity is a vertex return True.
1237
+
1238
+ Parameter
1239
+ =========
1240
+
1241
+ ent :
1242
+ Denotes a geometric entity representing a point.
1243
+
1244
+ Examples
1245
+ ========
1246
+
1247
+ >>> from sympy import Point
1248
+ >>> from sympy.integrals.intpoly import is_vertex
1249
+ >>> is_vertex((2, 3))
1250
+ True
1251
+ >>> is_vertex((2, 3, 6))
1252
+ True
1253
+ >>> is_vertex(Point(2, 3))
1254
+ True
1255
+ """
1256
+ if isinstance(ent, tuple):
1257
+ if len(ent) in [2, 3]:
1258
+ return True
1259
+ elif isinstance(ent, Point):
1260
+ return True
1261
+ return False
1262
+
1263
+
1264
+ def plot_polytope(poly):
1265
+ """Plots the 2D polytope using the functions written in plotting
1266
+ module which in turn uses matplotlib backend.
1267
+
1268
+ Parameter
1269
+ =========
1270
+
1271
+ poly:
1272
+ Denotes a 2-Polytope.
1273
+ """
1274
+ from sympy.plotting.plot import Plot, List2DSeries
1275
+
1276
+ xl = [vertex.x for vertex in poly.vertices]
1277
+ yl = [vertex.y for vertex in poly.vertices]
1278
+
1279
+ xl.append(poly.vertices[0].x) # Closing the polygon
1280
+ yl.append(poly.vertices[0].y)
1281
+
1282
+ l2ds = List2DSeries(xl, yl)
1283
+ p = Plot(l2ds, axes='label_axes=True')
1284
+ p.show()
1285
+
1286
+
1287
+ def plot_polynomial(expr):
1288
+ """Plots the polynomial using the functions written in
1289
+ plotting module which in turn uses matplotlib backend.
1290
+
1291
+ Parameter
1292
+ =========
1293
+
1294
+ expr:
1295
+ Denotes a polynomial(SymPy expression).
1296
+ """
1297
+ from sympy.plotting.plot import plot3d, plot
1298
+ gens = expr.free_symbols
1299
+ if len(gens) == 2:
1300
+ plot3d(expr)
1301
+ else:
1302
+ plot(expr)
venv/lib/python3.10/site-packages/sympy/integrals/laplace.py ADDED
@@ -0,0 +1,1761 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """Laplace Transforms"""
2
+ from sympy.core import S, pi, I
3
+ from sympy.core.add import Add
4
+ from sympy.core.cache import cacheit
5
+ from sympy.core.function import (
6
+ AppliedUndef, Derivative, expand, expand_complex, expand_mul, expand_trig,
7
+ Lambda, WildFunction, diff)
8
+ from sympy.core.mul import Mul, prod
9
+ from sympy.core.relational import _canonical, Ge, Gt, Lt, Unequality, Eq
10
+ from sympy.core.sorting import ordered
11
+ from sympy.core.symbol import Dummy, symbols, Wild
12
+ from sympy.functions.elementary.complexes import (
13
+ re, im, arg, Abs, polar_lift, periodic_argument)
14
+ from sympy.functions.elementary.exponential import exp, log
15
+ from sympy.functions.elementary.hyperbolic import cosh, coth, sinh, asinh
16
+ from sympy.functions.elementary.miscellaneous import Max, Min, sqrt
17
+ from sympy.functions.elementary.piecewise import Piecewise
18
+ from sympy.functions.elementary.trigonometric import cos, sin, atan
19
+ from sympy.functions.special.bessel import besseli, besselj, besselk, bessely
20
+ from sympy.functions.special.delta_functions import DiracDelta, Heaviside
21
+ from sympy.functions.special.error_functions import erf, erfc, Ei
22
+ from sympy.functions.special.gamma_functions import digamma, gamma, lowergamma
23
+ from sympy.integrals import integrate, Integral
24
+ from sympy.integrals.transforms import (
25
+ _simplify, IntegralTransform, IntegralTransformError)
26
+ from sympy.logic.boolalg import to_cnf, conjuncts, disjuncts, Or, And
27
+ from sympy.matrices.matrices import MatrixBase
28
+ from sympy.polys.matrices.linsolve import _lin_eq2dict
29
+ from sympy.polys.polyerrors import PolynomialError
30
+ from sympy.polys.polyroots import roots
31
+ from sympy.polys.polytools import Poly
32
+ from sympy.polys.rationaltools import together
33
+ from sympy.polys.rootoftools import RootSum
34
+ from sympy.utilities.exceptions import (
35
+ sympy_deprecation_warning, SymPyDeprecationWarning, ignore_warnings)
36
+ from sympy.utilities.misc import debug, debugf
37
+
38
+
39
+ def _simplifyconds(expr, s, a):
40
+ r"""
41
+ Naively simplify some conditions occurring in ``expr``,
42
+ given that `\operatorname{Re}(s) > a`.
43
+
44
+ Examples
45
+ ========
46
+
47
+ >>> from sympy.integrals.laplace import _simplifyconds
48
+ >>> from sympy.abc import x
49
+ >>> from sympy import sympify as S
50
+ >>> _simplifyconds(abs(x**2) < 1, x, 1)
51
+ False
52
+ >>> _simplifyconds(abs(x**2) < 1, x, 2)
53
+ False
54
+ >>> _simplifyconds(abs(x**2) < 1, x, 0)
55
+ Abs(x**2) < 1
56
+ >>> _simplifyconds(abs(1/x**2) < 1, x, 1)
57
+ True
58
+ >>> _simplifyconds(S(1) < abs(x), x, 1)
59
+ True
60
+ >>> _simplifyconds(S(1) < abs(1/x), x, 1)
61
+ False
62
+
63
+ >>> from sympy import Ne
64
+ >>> _simplifyconds(Ne(1, x**3), x, 1)
65
+ True
66
+ >>> _simplifyconds(Ne(1, x**3), x, 2)
67
+ True
68
+ >>> _simplifyconds(Ne(1, x**3), x, 0)
69
+ Ne(1, x**3)
70
+ """
71
+
72
+ def power(ex):
73
+ if ex == s:
74
+ return 1
75
+ if ex.is_Pow and ex.base == s:
76
+ return ex.exp
77
+ return None
78
+
79
+ def bigger(ex1, ex2):
80
+ """ Return True only if |ex1| > |ex2|, False only if |ex1| < |ex2|.
81
+ Else return None. """
82
+ if ex1.has(s) and ex2.has(s):
83
+ return None
84
+ if isinstance(ex1, Abs):
85
+ ex1 = ex1.args[0]
86
+ if isinstance(ex2, Abs):
87
+ ex2 = ex2.args[0]
88
+ if ex1.has(s):
89
+ return bigger(1/ex2, 1/ex1)
90
+ n = power(ex2)
91
+ if n is None:
92
+ return None
93
+ try:
94
+ if n > 0 and (Abs(ex1) <= Abs(a)**n) == S.true:
95
+ return False
96
+ if n < 0 and (Abs(ex1) >= Abs(a)**n) == S.true:
97
+ return True
98
+ except TypeError:
99
+ pass
100
+
101
+ def replie(x, y):
102
+ """ simplify x < y """
103
+ if (not (x.is_positive or isinstance(x, Abs))
104
+ or not (y.is_positive or isinstance(y, Abs))):
105
+ return (x < y)
106
+ r = bigger(x, y)
107
+ if r is not None:
108
+ return not r
109
+ return (x < y)
110
+
111
+ def replue(x, y):
112
+ b = bigger(x, y)
113
+ if b in (True, False):
114
+ return True
115
+ return Unequality(x, y)
116
+
117
+ def repl(ex, *args):
118
+ if ex in (True, False):
119
+ return bool(ex)
120
+ return ex.replace(*args)
121
+ from sympy.simplify.radsimp import collect_abs
122
+ expr = collect_abs(expr)
123
+ expr = repl(expr, Lt, replie)
124
+ expr = repl(expr, Gt, lambda x, y: replie(y, x))
125
+ expr = repl(expr, Unequality, replue)
126
+ return S(expr)
127
+
128
+
129
+ def expand_dirac_delta(expr):
130
+ """
131
+ Expand an expression involving DiractDelta to get it as a linear
132
+ combination of DiracDelta functions.
133
+ """
134
+ return _lin_eq2dict(expr, expr.atoms(DiracDelta))
135
+
136
+
137
+ def _laplace_transform_integration(f, t, s_, simplify=True):
138
+ """ The backend function for doing Laplace transforms by integration.
139
+
140
+ This backend assumes that the frontend has already split sums
141
+ such that `f` is to an addition anymore.
142
+ """
143
+ s = Dummy('s')
144
+ debugf('[LT _l_t_i ] started with (%s, %s, %s)', (f, t, s))
145
+ debugf('[LT _l_t_i ] and simplify=%s', (simplify, ))
146
+
147
+ if f.has(DiracDelta):
148
+ return None
149
+
150
+ F = integrate(f*exp(-s*t), (t, S.Zero, S.Infinity))
151
+ debugf('[LT _l_t_i ] integrated: %s', (F, ))
152
+
153
+ if not F.has(Integral):
154
+ return _simplify(F.subs(s, s_), simplify), S.NegativeInfinity, S.true
155
+
156
+ if not F.is_Piecewise:
157
+ debug('[LT _l_t_i ] not piecewise.')
158
+ return None
159
+
160
+ F, cond = F.args[0]
161
+ if F.has(Integral):
162
+ debug('[LT _l_t_i ] integral in unexpected form.')
163
+ return None
164
+
165
+ def process_conds(conds):
166
+ """ Turn ``conds`` into a strip and auxiliary conditions. """
167
+ from sympy.solvers.inequalities import _solve_inequality
168
+ a = S.NegativeInfinity
169
+ aux = S.true
170
+ conds = conjuncts(to_cnf(conds))
171
+ p, q, w1, w2, w3, w4, w5 = symbols(
172
+ 'p q w1 w2 w3 w4 w5', cls=Wild, exclude=[s])
173
+ patterns = (
174
+ p*Abs(arg((s + w3)*q)) < w2,
175
+ p*Abs(arg((s + w3)*q)) <= w2,
176
+ Abs(periodic_argument((s + w3)**p*q, w1)) < w2,
177
+ Abs(periodic_argument((s + w3)**p*q, w1)) <= w2,
178
+ Abs(periodic_argument((polar_lift(s + w3))**p*q, w1)) < w2,
179
+ Abs(periodic_argument((polar_lift(s + w3))**p*q, w1)) <= w2)
180
+ for c in conds:
181
+ a_ = S.Infinity
182
+ aux_ = []
183
+ for d in disjuncts(c):
184
+ if d.is_Relational and s in d.rhs.free_symbols:
185
+ d = d.reversed
186
+ if d.is_Relational and isinstance(d, (Ge, Gt)):
187
+ d = d.reversedsign
188
+ for pat in patterns:
189
+ m = d.match(pat)
190
+ if m:
191
+ break
192
+ if m and m[q].is_positive and m[w2]/m[p] == pi/2:
193
+ d = -re(s + m[w3]) < 0
194
+ m = d.match(p - cos(w1*Abs(arg(s*w5))*w2)*Abs(s**w3)**w4 < 0)
195
+ if not m:
196
+ m = d.match(
197
+ cos(p - Abs(periodic_argument(s**w1*w5, q))*w2) *
198
+ Abs(s**w3)**w4 < 0)
199
+ if not m:
200
+ m = d.match(
201
+ p - cos(
202
+ Abs(periodic_argument(polar_lift(s)**w1*w5, q))*w2
203
+ )*Abs(s**w3)**w4 < 0)
204
+ if m and all(m[wild].is_positive for wild in [
205
+ w1, w2, w3, w4, w5]):
206
+ d = re(s) > m[p]
207
+ d_ = d.replace(
208
+ re, lambda x: x.expand().as_real_imag()[0]).subs(re(s), t)
209
+ if (
210
+ not d.is_Relational or d.rel_op in ('==', '!=')
211
+ or d_.has(s) or not d_.has(t)):
212
+ aux_ += [d]
213
+ continue
214
+ soln = _solve_inequality(d_, t)
215
+ if not soln.is_Relational or soln.rel_op in ('==', '!='):
216
+ aux_ += [d]
217
+ continue
218
+ if soln.lts == t:
219
+ debug('[LT _l_t_i ] convergence not in half-plane.')
220
+ return None
221
+ else:
222
+ a_ = Min(soln.lts, a_)
223
+ if a_ is not S.Infinity:
224
+ a = Max(a_, a)
225
+ else:
226
+ aux = And(aux, Or(*aux_))
227
+ return a, aux.canonical if aux.is_Relational else aux
228
+
229
+ conds = [process_conds(c) for c in disjuncts(cond)]
230
+ conds2 = [x for x in conds if x[1] !=
231
+ S.false and x[0] is not S.NegativeInfinity]
232
+ if not conds2:
233
+ conds2 = [x for x in conds if x[1] != S.false]
234
+ conds = list(ordered(conds2))
235
+
236
+ def cnt(expr):
237
+ if expr in (True, False):
238
+ return 0
239
+ return expr.count_ops()
240
+ conds.sort(key=lambda x: (-x[0], cnt(x[1])))
241
+
242
+ if not conds:
243
+ debug('[LT _l_t_i ] no convergence found.')
244
+ return None
245
+ a, aux = conds[0] # XXX is [0] always the right one?
246
+
247
+ def sbs(expr):
248
+ return expr.subs(s, s_)
249
+ if simplify:
250
+ F = _simplifyconds(F, s, a)
251
+ aux = _simplifyconds(aux, s, a)
252
+ return _simplify(F.subs(s, s_), simplify), sbs(a), _canonical(sbs(aux))
253
+
254
+
255
+ def _laplace_deep_collect(f, t):
256
+ """
257
+ This is an internal helper function that traverses through the epression
258
+ tree of `f(t)` and collects arguments. The purpose of it is that
259
+ anything like `f(w*t-1*t-c)` will be written as `f((w-1)*t-c)` such that
260
+ it can match `f(a*t+b)`.
261
+ """
262
+ func = f.func
263
+ args = list(f.args)
264
+ if len(f.args) == 0:
265
+ return f
266
+ else:
267
+ args = [_laplace_deep_collect(arg, t) for arg in args]
268
+ if func.is_Add:
269
+ return func(*args).collect(t)
270
+ else:
271
+ return func(*args)
272
+
273
+
274
+ @cacheit
275
+ def _laplace_build_rules():
276
+ """
277
+ This is an internal helper function that returns the table of Laplace
278
+ transform rules in terms of the time variable `t` and the frequency
279
+ variable `s`. It is used by ``_laplace_apply_rules``. Each entry is a
280
+ tuple containing:
281
+
282
+ (time domain pattern,
283
+ frequency-domain replacement,
284
+ condition for the rule to be applied,
285
+ convergence plane,
286
+ preparation function)
287
+
288
+ The preparation function is a function with one argument that is applied
289
+ to the expression before matching. For most rules it should be
290
+ ``_laplace_deep_collect``.
291
+ """
292
+ t = Dummy('t')
293
+ s = Dummy('s')
294
+ a = Wild('a', exclude=[t])
295
+ b = Wild('b', exclude=[t])
296
+ n = Wild('n', exclude=[t])
297
+ tau = Wild('tau', exclude=[t])
298
+ omega = Wild('omega', exclude=[t])
299
+ def dco(f): return _laplace_deep_collect(f, t)
300
+ debug('_laplace_build_rules is building rules')
301
+
302
+ laplace_transform_rules = [
303
+ (a, a/s,
304
+ S.true, S.Zero, dco), # 4.2.1
305
+ (DiracDelta(a*t-b), exp(-s*b/a)/Abs(a),
306
+ Or(And(a > 0, b >= 0), And(a < 0, b <= 0)),
307
+ S.NegativeInfinity, dco), # Not in Bateman54
308
+ (DiracDelta(a*t-b), S(0),
309
+ Or(And(a < 0, b >= 0), And(a > 0, b <= 0)),
310
+ S.NegativeInfinity, dco), # Not in Bateman54
311
+ (Heaviside(a*t-b), exp(-s*b/a)/s,
312
+ And(a > 0, b > 0), S.Zero, dco), # 4.4.1
313
+ (Heaviside(a*t-b), (1-exp(-s*b/a))/s,
314
+ And(a < 0, b < 0), S.Zero, dco), # 4.4.1
315
+ (Heaviside(a*t-b), 1/s,
316
+ And(a > 0, b <= 0), S.Zero, dco), # 4.4.1
317
+ (Heaviside(a*t-b), 0,
318
+ And(a < 0, b > 0), S.Zero, dco), # 4.4.1
319
+ (t, 1/s**2,
320
+ S.true, S.Zero, dco), # 4.2.3
321
+ (1/(a*t+b), -exp(-b/a*s)*Ei(-b/a*s)/a,
322
+ Abs(arg(b/a)) < pi, S.Zero, dco), # 4.2.6
323
+ (1/sqrt(a*t+b), sqrt(a*pi/s)*exp(b/a*s)*erfc(sqrt(b/a*s))/a,
324
+ Abs(arg(b/a)) < pi, S.Zero, dco), # 4.2.18
325
+ ((a*t+b)**(-S(3)/2),
326
+ 2*b**(-S(1)/2)-2*(pi*s/a)**(S(1)/2)*exp(b/a*s) * erfc(sqrt(b/a*s))/a,
327
+ Abs(arg(b/a)) < pi, S.Zero, dco), # 4.2.20
328
+ (sqrt(t)/(t+b), sqrt(pi/s)-pi*sqrt(b)*exp(b*s)*erfc(sqrt(b*s)),
329
+ Abs(arg(b)) < pi, S.Zero, dco), # 4.2.22
330
+ (1/(a*sqrt(t) + t**(3/2)), pi*a**(S(1)/2)*exp(a*s)*erfc(sqrt(a*s)),
331
+ S.true, S.Zero, dco), # Not in Bateman54
332
+ (t**n, gamma(n+1)/s**(n+1),
333
+ n > -1, S.Zero, dco), # 4.3.1
334
+ ((a*t+b)**n, lowergamma(n+1, b/a*s)*exp(-b/a*s)/s**(n+1)/a,
335
+ And(n > -1, Abs(arg(b/a)) < pi), S.Zero, dco), # 4.3.4
336
+ (t**n/(t+a), a**n*gamma(n+1)*lowergamma(-n, a*s),
337
+ And(n > -1, Abs(arg(a)) < pi), S.Zero, dco), # 4.3.7
338
+ (exp(a*t-tau), exp(-tau)/(s-a),
339
+ S.true, re(a), dco), # 4.5.1
340
+ (t*exp(a*t-tau), exp(-tau)/(s-a)**2,
341
+ S.true, re(a), dco), # 4.5.2
342
+ (t**n*exp(a*t), gamma(n+1)/(s-a)**(n+1),
343
+ re(n) > -1, re(a), dco), # 4.5.3
344
+ (exp(-a*t**2), sqrt(pi/4/a)*exp(s**2/4/a)*erfc(s/sqrt(4*a)),
345
+ re(a) > 0, S.Zero, dco), # 4.5.21
346
+ (t*exp(-a*t**2),
347
+ 1/(2*a)-2/sqrt(pi)/(4*a)**(S(3)/2)*s*erfc(s/sqrt(4*a)),
348
+ re(a) > 0, S.Zero, dco), # 4.5.22
349
+ (exp(-a/t), 2*sqrt(a/s)*besselk(1, 2*sqrt(a*s)),
350
+ re(a) >= 0, S.Zero, dco), # 4.5.25
351
+ (sqrt(t)*exp(-a/t),
352
+ S(1)/2*sqrt(pi/s**3)*(1+2*sqrt(a*s))*exp(-2*sqrt(a*s)),
353
+ re(a) >= 0, S.Zero, dco), # 4.5.26
354
+ (exp(-a/t)/sqrt(t), sqrt(pi/s)*exp(-2*sqrt(a*s)),
355
+ re(a) >= 0, S.Zero, dco), # 4.5.27
356
+ (exp(-a/t)/(t*sqrt(t)), sqrt(pi/a)*exp(-2*sqrt(a*s)),
357
+ re(a) > 0, S.Zero, dco), # 4.5.28
358
+ (t**n*exp(-a/t), 2*(a/s)**((n+1)/2)*besselk(n+1, 2*sqrt(a*s)),
359
+ re(a) > 0, S.Zero, dco), # 4.5.29
360
+ (exp(-2*sqrt(a*t)),
361
+ s**(-1)-sqrt(pi*a)*s**(-S(3)/2)*exp(a/s) * erfc(sqrt(a/s)),
362
+ Abs(arg(a)) < pi, S.Zero, dco), # 4.5.31
363
+ (exp(-2*sqrt(a*t))/sqrt(t), (pi/s)**(S(1)/2)*exp(a/s)*erfc(sqrt(a/s)),
364
+ Abs(arg(a)) < pi, S.Zero, dco), # 4.5.33
365
+ (log(a*t), -log(exp(S.EulerGamma)*s/a)/s,
366
+ a > 0, S.Zero, dco), # 4.6.1
367
+ (log(1+a*t), -exp(s/a)/s*Ei(-s/a),
368
+ Abs(arg(a)) < pi, S.Zero, dco), # 4.6.4
369
+ (log(a*t+b), (log(b)-exp(s/b/a)/s*a*Ei(-s/b))/s*a,
370
+ And(a > 0, Abs(arg(b)) < pi), S.Zero, dco), # 4.6.5
371
+ (log(t)/sqrt(t), -sqrt(pi/s)*log(4*s*exp(S.EulerGamma)),
372
+ S.true, S.Zero, dco), # 4.6.9
373
+ (t**n*log(t), gamma(n+1)*s**(-n-1)*(digamma(n+1)-log(s)),
374
+ re(n) > -1, S.Zero, dco), # 4.6.11
375
+ (log(a*t)**2, (log(exp(S.EulerGamma)*s/a)**2+pi**2/6)/s,
376
+ a > 0, S.Zero, dco), # 4.6.13
377
+ (sin(omega*t), omega/(s**2+omega**2),
378
+ S.true, Abs(im(omega)), dco), # 4,7,1
379
+ (Abs(sin(omega*t)), omega/(s**2+omega**2)*coth(pi*s/2/omega),
380
+ omega > 0, S.Zero, dco), # 4.7.2
381
+ (sin(omega*t)/t, atan(omega/s),
382
+ S.true, Abs(im(omega)), dco), # 4.7.16
383
+ (sin(omega*t)**2/t, log(1+4*omega**2/s**2)/4,
384
+ S.true, 2*Abs(im(omega)), dco), # 4.7.17
385
+ (sin(omega*t)**2/t**2,
386
+ omega*atan(2*omega/s)-s*log(1+4*omega**2/s**2)/4,
387
+ S.true, 2*Abs(im(omega)), dco), # 4.7.20
388
+ (sin(2*sqrt(a*t)), sqrt(pi*a)/s/sqrt(s)*exp(-a/s),
389
+ S.true, S.Zero, dco), # 4.7.32
390
+ (sin(2*sqrt(a*t))/t, pi*erf(sqrt(a/s)),
391
+ S.true, S.Zero, dco), # 4.7.34
392
+ (cos(omega*t), s/(s**2+omega**2),
393
+ S.true, Abs(im(omega)), dco), # 4.7.43
394
+ (cos(omega*t)**2, (s**2+2*omega**2)/(s**2+4*omega**2)/s,
395
+ S.true, 2*Abs(im(omega)), dco), # 4.7.45
396
+ (sqrt(t)*cos(2*sqrt(a*t)), sqrt(pi)/2*s**(-S(5)/2)*(s-2*a)*exp(-a/s),
397
+ S.true, S.Zero, dco), # 4.7.66
398
+ (cos(2*sqrt(a*t))/sqrt(t), sqrt(pi/s)*exp(-a/s),
399
+ S.true, S.Zero, dco), # 4.7.67
400
+ (sin(a*t)*sin(b*t), 2*a*b*s/(s**2+(a+b)**2)/(s**2+(a-b)**2),
401
+ S.true, Abs(im(a))+Abs(im(b)), dco), # 4.7.78
402
+ (cos(a*t)*sin(b*t), b*(s**2-a**2+b**2)/(s**2+(a+b)**2)/(s**2+(a-b)**2),
403
+ S.true, Abs(im(a))+Abs(im(b)), dco), # 4.7.79
404
+ (cos(a*t)*cos(b*t), s*(s**2+a**2+b**2)/(s**2+(a+b)**2)/(s**2+(a-b)**2),
405
+ S.true, Abs(im(a))+Abs(im(b)), dco), # 4.7.80
406
+ (sinh(a*t), a/(s**2-a**2),
407
+ S.true, Abs(re(a)), dco), # 4.9.1
408
+ (cosh(a*t), s/(s**2-a**2),
409
+ S.true, Abs(re(a)), dco), # 4.9.2
410
+ (sinh(a*t)**2, 2*a**2/(s**3-4*a**2*s),
411
+ S.true, 2*Abs(re(a)), dco), # 4.9.3
412
+ (cosh(a*t)**2, (s**2-2*a**2)/(s**3-4*a**2*s),
413
+ S.true, 2*Abs(re(a)), dco), # 4.9.4
414
+ (sinh(a*t)/t, log((s+a)/(s-a))/2,
415
+ S.true, Abs(re(a)), dco), # 4.9.12
416
+ (t**n*sinh(a*t), gamma(n+1)/2*((s-a)**(-n-1)-(s+a)**(-n-1)),
417
+ n > -2, Abs(a), dco), # 4.9.18
418
+ (t**n*cosh(a*t), gamma(n+1)/2*((s-a)**(-n-1)+(s+a)**(-n-1)),
419
+ n > -1, Abs(a), dco), # 4.9.19
420
+ (sinh(2*sqrt(a*t)), sqrt(pi*a)/s/sqrt(s)*exp(a/s),
421
+ S.true, S.Zero, dco), # 4.9.34
422
+ (cosh(2*sqrt(a*t)), 1/s+sqrt(pi*a)/s/sqrt(s)*exp(a/s)*erf(sqrt(a/s)),
423
+ S.true, S.Zero, dco), # 4.9.35
424
+ (
425
+ sqrt(t)*sinh(2*sqrt(a*t)),
426
+ pi**(S(1)/2)*s**(-S(5)/2)*(s/2+a) *
427
+ exp(a/s)*erf(sqrt(a/s))-a**(S(1)/2)*s**(-2),
428
+ S.true, S.Zero, dco), # 4.9.36
429
+ (sqrt(t)*cosh(2*sqrt(a*t)), pi**(S(1)/2)*s**(-S(5)/2)*(s/2+a)*exp(a/s),
430
+ S.true, S.Zero, dco), # 4.9.37
431
+ (sinh(2*sqrt(a*t))/sqrt(t),
432
+ pi**(S(1)/2)*s**(-S(1)/2)*exp(a/s) * erf(sqrt(a/s)),
433
+ S.true, S.Zero, dco), # 4.9.38
434
+ (cosh(2*sqrt(a*t))/sqrt(t), pi**(S(1)/2)*s**(-S(1)/2)*exp(a/s),
435
+ S.true, S.Zero, dco), # 4.9.39
436
+ (sinh(sqrt(a*t))**2/sqrt(t), pi**(S(1)/2)/2*s**(-S(1)/2)*(exp(a/s)-1),
437
+ S.true, S.Zero, dco), # 4.9.40
438
+ (cosh(sqrt(a*t))**2/sqrt(t), pi**(S(1)/2)/2*s**(-S(1)/2)*(exp(a/s)+1),
439
+ S.true, S.Zero, dco), # 4.9.41
440
+ (erf(a*t), exp(s**2/(2*a)**2)*erfc(s/(2*a))/s,
441
+ 4*Abs(arg(a)) < pi, S.Zero, dco), # 4.12.2
442
+ (erf(sqrt(a*t)), sqrt(a)/sqrt(s+a)/s,
443
+ S.true, Max(S.Zero, -re(a)), dco), # 4.12.4
444
+ (exp(a*t)*erf(sqrt(a*t)), sqrt(a)/sqrt(s)/(s-a),
445
+ S.true, Max(S.Zero, re(a)), dco), # 4.12.5
446
+ (erf(sqrt(a/t)/2), (1-exp(-sqrt(a*s)))/s,
447
+ re(a) > 0, S.Zero, dco), # 4.12.6
448
+ (erfc(sqrt(a*t)), (sqrt(s+a)-sqrt(a))/sqrt(s+a)/s,
449
+ S.true, -re(a), dco), # 4.12.9
450
+ (exp(a*t)*erfc(sqrt(a*t)), 1/(s+sqrt(a*s)),
451
+ S.true, S.Zero, dco), # 4.12.10
452
+ (erfc(sqrt(a/t)/2), exp(-sqrt(a*s))/s,
453
+ re(a) > 0, S.Zero, dco), # 4.2.11
454
+ (besselj(n, a*t), a**n/(sqrt(s**2+a**2)*(s+sqrt(s**2+a**2))**n),
455
+ re(n) > -1, Abs(im(a)), dco), # 4.14.1
456
+ (t**b*besselj(n, a*t),
457
+ 2**n/sqrt(pi)*gamma(n+S.Half)*a**n*(s**2+a**2)**(-n-S.Half),
458
+ And(re(n) > -S.Half, Eq(b, n)), Abs(im(a)), dco), # 4.14.7
459
+ (t**b*besselj(n, a*t),
460
+ 2**(n+1)/sqrt(pi)*gamma(n+S(3)/2)*a**n*s*(s**2+a**2)**(-n-S(3)/2),
461
+ And(re(n) > -1, Eq(b, n+1)), Abs(im(a)), dco), # 4.14.8
462
+ (besselj(0, 2*sqrt(a*t)), exp(-a/s)/s,
463
+ S.true, S.Zero, dco), # 4.14.25
464
+ (t**(b)*besselj(n, 2*sqrt(a*t)), a**(n/2)*s**(-n-1)*exp(-a/s),
465
+ And(re(n) > -1, Eq(b, n*S.Half)), S.Zero, dco), # 4.14.30
466
+ (besselj(0, a*sqrt(t**2+b*t)),
467
+ exp(b*s-b*sqrt(s**2+a**2))/sqrt(s**2+a**2),
468
+ Abs(arg(b)) < pi, Abs(im(a)), dco), # 4.15.19
469
+ (besseli(n, a*t), a**n/(sqrt(s**2-a**2)*(s+sqrt(s**2-a**2))**n),
470
+ re(n) > -1, Abs(re(a)), dco), # 4.16.1
471
+ (t**b*besseli(n, a*t),
472
+ 2**n/sqrt(pi)*gamma(n+S.Half)*a**n*(s**2-a**2)**(-n-S.Half),
473
+ And(re(n) > -S.Half, Eq(b, n)), Abs(re(a)), dco), # 4.16.6
474
+ (t**b*besseli(n, a*t),
475
+ 2**(n+1)/sqrt(pi)*gamma(n+S(3)/2)*a**n*s*(s**2-a**2)**(-n-S(3)/2),
476
+ And(re(n) > -1, Eq(b, n+1)), Abs(re(a)), dco), # 4.16.7
477
+ (t**(b)*besseli(n, 2*sqrt(a*t)), a**(n/2)*s**(-n-1)*exp(a/s),
478
+ And(re(n) > -1, Eq(b, n*S.Half)), S.Zero, dco), # 4.16.18
479
+ (bessely(0, a*t), -2/pi*asinh(s/a)/sqrt(s**2+a**2),
480
+ S.true, Abs(im(a)), dco), # 4.15.44
481
+ (besselk(0, a*t), log((s + sqrt(s**2-a**2))/a)/(sqrt(s**2-a**2)),
482
+ S.true, -re(a), dco) # 4.16.23
483
+ ]
484
+ return laplace_transform_rules, t, s
485
+
486
+
487
+ def _laplace_rule_timescale(f, t, s):
488
+ """
489
+ This function applies the time-scaling rule of the Laplace transform in
490
+ a straight-forward way. For example, if it gets ``(f(a*t), t, s)``, it will
491
+ compute ``LaplaceTransform(f(t)/a, t, s/a)`` if ``a>0``.
492
+ """
493
+
494
+ a = Wild('a', exclude=[t])
495
+ g = WildFunction('g', nargs=1)
496
+ ma1 = f.match(g)
497
+ if ma1:
498
+ arg = ma1[g].args[0].collect(t)
499
+ ma2 = arg.match(a*t)
500
+ if ma2 and ma2[a].is_positive and ma2[a] != 1:
501
+ debug('_laplace_apply_prog rules match:')
502
+ debugf(' f: %s _ %s, %s )', (f, ma1, ma2))
503
+ debug(' rule: time scaling (4.1.4)')
504
+ r, pr, cr = _laplace_transform(1/ma2[a]*ma1[g].func(t),
505
+ t, s/ma2[a], simplify=False)
506
+ return (r, pr, cr)
507
+ return None
508
+
509
+
510
+ def _laplace_rule_heaviside(f, t, s):
511
+ """
512
+ This function deals with time-shifted Heaviside step functions. If the time
513
+ shift is positive, it applies the time-shift rule of the Laplace transform.
514
+ For example, if it gets ``(Heaviside(t-a)*f(t), t, s)``, it will compute
515
+ ``exp(-a*s)*LaplaceTransform(f(t+a), t, s)``.
516
+
517
+ If the time shift is negative, the Heaviside function is simply removed
518
+ as it means nothing to the Laplace transform.
519
+
520
+ The function does not remove a factor ``Heaviside(t)``; this is done by
521
+ the simple rules.
522
+ """
523
+
524
+ a = Wild('a', exclude=[t])
525
+ y = Wild('y')
526
+ g = Wild('g')
527
+ ma1 = f.match(Heaviside(y)*g)
528
+ if ma1:
529
+ ma2 = ma1[y].match(t-a)
530
+ if ma2 and ma2[a].is_positive:
531
+ debug('_laplace_apply_prog_rules match:')
532
+ debugf(' f: %s ( %s, %s )', (f, ma1, ma2))
533
+ debug(' rule: time shift (4.1.4)')
534
+ r, pr, cr = _laplace_transform(ma1[g].subs(t, t+ma2[a]), t, s,
535
+ simplify=False)
536
+ return (exp(-ma2[a]*s)*r, pr, cr)
537
+ if ma2 and ma2[a].is_negative:
538
+ debug('_laplace_apply_prog_rules match:')
539
+ debugf(' f: %s ( %s, %s )', (f, ma1, ma2))
540
+ debug(' rule: Heaviside factor, negative time shift (4.1.4)')
541
+ r, pr, cr = _laplace_transform(ma1[g], t, s, simplify=False)
542
+ return (r, pr, cr)
543
+ return None
544
+
545
+
546
+ def _laplace_rule_exp(f, t, s):
547
+ """
548
+ If this function finds a factor ``exp(a*t)``, it applies the
549
+ frequency-shift rule of the Laplace transform and adjusts the convergence
550
+ plane accordingly. For example, if it gets ``(exp(-a*t)*f(t), t, s)``, it
551
+ will compute ``LaplaceTransform(f(t), t, s+a)``.
552
+ """
553
+
554
+ a = Wild('a', exclude=[t])
555
+ y = Wild('y')
556
+ z = Wild('z')
557
+ ma1 = f.match(exp(y)*z)
558
+ if ma1:
559
+ ma2 = ma1[y].collect(t).match(a*t)
560
+ if ma2:
561
+ debug('_laplace_apply_prog_rules match:')
562
+ debugf(' f: %s ( %s, %s )', (f, ma1, ma2))
563
+ debug(' rule: multiply with exp (4.1.5)')
564
+ r, pr, cr = _laplace_transform(ma1[z], t, s-ma2[a],
565
+ simplify=False)
566
+ return (r, pr+re(ma2[a]), cr)
567
+ return None
568
+
569
+
570
+ def _laplace_rule_delta(f, t, s):
571
+ """
572
+ If this function finds a factor ``DiracDelta(b*t-a)``, it applies the
573
+ masking property of the delta distribution. For example, if it gets
574
+ ``(DiracDelta(t-a)*f(t), t, s)``, it will return
575
+ ``(f(a)*exp(-a*s), -a, True)``.
576
+ """
577
+ # This rule is not in Bateman54
578
+
579
+ a = Wild('a', exclude=[t])
580
+ b = Wild('b', exclude=[t])
581
+
582
+ y = Wild('y')
583
+ z = Wild('z')
584
+ ma1 = f.match(DiracDelta(y)*z)
585
+ if ma1 and not ma1[z].has(DiracDelta):
586
+ ma2 = ma1[y].collect(t).match(b*t-a)
587
+ if ma2:
588
+ debug('_laplace_apply_prog_rules match:')
589
+ debugf(' f: %s ( %s, %s )', (f, ma1, ma2))
590
+ debug(' rule: multiply with DiracDelta')
591
+ loc = ma2[a]/ma2[b]
592
+ if re(loc) >= 0 and im(loc) == 0:
593
+ r = exp(-ma2[a]/ma2[b]*s)*ma1[z].subs(t, ma2[a]/ma2[b])/ma2[b]
594
+ return (r, S.NegativeInfinity, S.true)
595
+ else:
596
+ return (0, S.NegativeInfinity, S.true)
597
+ if ma1[y].is_polynomial(t):
598
+ ro = roots(ma1[y], t)
599
+ if roots is not {} and set(ro.values()) == {1}:
600
+ slope = diff(ma1[y], t)
601
+ r = Add(
602
+ *[exp(-x*s)*ma1[z].subs(t, s)/slope.subs(t, x)
603
+ for x in list(ro.keys()) if im(x) == 0 and re(x) >= 0])
604
+ return (r, S.NegativeInfinity, S.true)
605
+ return None
606
+
607
+
608
+ def _laplace_trig_split(fn):
609
+ """
610
+ Helper function for `_laplace_rule_trig`. This function returns two terms
611
+ `f` and `g`. `f` contains all product terms with sin, cos, sinh, cosh in
612
+ them; `g` contains everything else.
613
+ """
614
+ trigs = [S.One]
615
+ other = [S.One]
616
+ for term in Mul.make_args(fn):
617
+ if term.has(sin, cos, sinh, cosh, exp):
618
+ trigs.append(term)
619
+ else:
620
+ other.append(term)
621
+ f = Mul(*trigs)
622
+ g = Mul(*other)
623
+ return f, g
624
+
625
+
626
+ def _laplace_trig_expsum(f, t):
627
+ """
628
+ Helper function for `_laplace_rule_trig`. This function expects the `f`
629
+ from `_laplace_trig_split`. It returns two lists `xm` and `xn`. `xm` is
630
+ a list of dictionaries with keys `k` and `a` representing a function
631
+ `k*exp(a*t)`. `xn` is a list of all terms that cannot be brought into
632
+ that form, which may happen, e.g., when a trigonometric function has
633
+ another function in its argument.
634
+ """
635
+ m = Wild('m')
636
+ p = Wild('p', exclude=[t])
637
+ xm = []
638
+ xn = []
639
+
640
+ x1 = f.rewrite(exp).expand()
641
+
642
+ for term in Add.make_args(x1):
643
+ if not term.has(t):
644
+ xm.append({'k': term, 'a': 0, re: 0, im: 0})
645
+ continue
646
+ term = term.powsimp(combine='exp')
647
+ if (r := term.match(p*exp(m))) is not None:
648
+ if (mp := r[m].as_poly(t)) is not None:
649
+ mc = mp.all_coeffs()
650
+ if len(mc) == 2:
651
+ xm.append({
652
+ 'k': r[p]*exp(mc[1]), 'a': mc[0],
653
+ re: re(mc[0]), im: im(mc[0])})
654
+ else:
655
+ xn.append(term)
656
+ else:
657
+ xn.append(term)
658
+ else:
659
+ xn.append(term)
660
+ return xm, xn
661
+
662
+
663
+ def _laplace_trig_ltex(xm, t, s):
664
+ """
665
+ Helper function for `_laplace_rule_trig`. This function takes the list of
666
+ exponentials `xm` from `_laplace_trig_expsum` and simplifies complex
667
+ conjugate and real symmetric poles. It returns the result as a sum and
668
+ the convergence plane.
669
+ """
670
+ results = []
671
+ planes = []
672
+
673
+ def _simpc(coeffs):
674
+ nc = coeffs.copy()
675
+ for k in range(len(nc)):
676
+ ri = nc[k].as_real_imag()
677
+ if ri[0].has(im):
678
+ nc[k] = nc[k].rewrite(cos)
679
+ else:
680
+ nc[k] = (ri[0] + I*ri[1]).rewrite(cos)
681
+ return nc
682
+
683
+ def _quadpole(t1, k1, k2, k3, s):
684
+ a, k0, a_r, a_i = t1['a'], t1['k'], t1[re], t1[im]
685
+ nc = [
686
+ k0 + k1 + k2 + k3,
687
+ a*(k0 + k1 - k2 - k3) - 2*I*a_i*k1 + 2*I*a_i*k2,
688
+ (
689
+ a**2*(-k0 - k1 - k2 - k3) +
690
+ a*(4*I*a_i*k0 + 4*I*a_i*k3) +
691
+ 4*a_i**2*k0 + 4*a_i**2*k3),
692
+ (
693
+ a**3*(-k0 - k1 + k2 + k3) +
694
+ a**2*(4*I*a_i*k0 + 2*I*a_i*k1 - 2*I*a_i*k2 - 4*I*a_i*k3) +
695
+ a*(4*a_i**2*k0 - 4*a_i**2*k3))
696
+ ]
697
+ dc = [
698
+ S.One, S.Zero, 2*a_i**2 - 2*a_r**2,
699
+ S.Zero, a_i**4 + 2*a_i**2*a_r**2 + a_r**4]
700
+ n = Add(
701
+ *[x*s**y for x, y in zip(_simpc(nc), range(len(nc))[::-1])])
702
+ d = Add(
703
+ *[x*s**y for x, y in zip(dc, range(len(dc))[::-1])])
704
+ debugf(' quadpole: (%s) / (%s)', (n, d))
705
+ return n/d
706
+
707
+ def _ccpole(t1, k1, s):
708
+ a, k0, a_r, a_i = t1['a'], t1['k'], t1[re], t1[im]
709
+ nc = [k0 + k1, -a*k0 - a*k1 + 2*I*a_i*k0]
710
+ dc = [S.One, -2*a_r, a_i**2 + a_r**2]
711
+ n = Add(
712
+ *[x*s**y for x, y in zip(_simpc(nc), range(len(nc))[::-1])])
713
+ d = Add(
714
+ *[x*s**y for x, y in zip(dc, range(len(dc))[::-1])])
715
+ debugf(' ccpole: (%s) / (%s)', (n, d))
716
+ return n/d
717
+
718
+ def _rspole(t1, k2, s):
719
+ a, k0, a_r, a_i = t1['a'], t1['k'], t1[re], t1[im]
720
+ nc = [k0 + k2, a*k0 - a*k2 - 2*I*a_i*k0]
721
+ dc = [S.One, -2*I*a_i, -a_i**2 - a_r**2]
722
+ n = Add(
723
+ *[x*s**y for x, y in zip(_simpc(nc), range(len(nc))[::-1])])
724
+ d = Add(
725
+ *[x*s**y for x, y in zip(dc, range(len(dc))[::-1])])
726
+ debugf(' rspole: (%s) / (%s)', (n, d))
727
+ return n/d
728
+
729
+ def _sypole(t1, k3, s):
730
+ a, k0 = t1['a'], t1['k']
731
+ nc = [k0 + k3, a*(k0 - k3)]
732
+ dc = [S.One, S.Zero, -a**2]
733
+ n = Add(
734
+ *[x*s**y for x, y in zip(_simpc(nc), range(len(nc))[::-1])])
735
+ d = Add(
736
+ *[x*s**y for x, y in zip(dc, range(len(dc))[::-1])])
737
+ debugf(' sypole: (%s) / (%s)', (n, d))
738
+ return n/d
739
+
740
+ def _simplepole(t1, s):
741
+ a, k0 = t1['a'], t1['k']
742
+ n = k0
743
+ d = s - a
744
+ debugf(' simplepole: (%s) / (%s)', (n, d))
745
+ return n/d
746
+
747
+ while len(xm) > 0:
748
+ t1 = xm.pop()
749
+ i_imagsym = None
750
+ i_realsym = None
751
+ i_pointsym = None
752
+ # The following code checks all remaining poles. If t1 is a pole at
753
+ # a+b*I, then we check for a-b*I, -a+b*I, and -a-b*I, and
754
+ # assign the respective indices to i_imagsym, i_realsym, i_pointsym.
755
+ # -a-b*I / i_pointsym only applies if both a and b are != 0.
756
+ for i in range(len(xm)):
757
+ real_eq = t1[re] == xm[i][re]
758
+ realsym = t1[re] == -xm[i][re]
759
+ imag_eq = t1[im] == xm[i][im]
760
+ imagsym = t1[im] == -xm[i][im]
761
+ if realsym and imagsym and t1[re] != 0 and t1[im] != 0:
762
+ i_pointsym = i
763
+ elif realsym and imag_eq and t1[re] != 0:
764
+ i_realsym = i
765
+ elif real_eq and imagsym and t1[im] != 0:
766
+ i_imagsym = i
767
+
768
+ # The next part looks for four possible pole constellations:
769
+ # quad: a+b*I, a-b*I, -a+b*I, -a-b*I
770
+ # cc: a+b*I, a-b*I (a may be zero)
771
+ # quad: a+b*I, -a+b*I (b may be zero)
772
+ # point: a+b*I, -a-b*I (a!=0 and b!=0 is needed, but that has been
773
+ # asserted when finding i_pointsym above.)
774
+ # If none apply, then t1 is a simple pole.
775
+ if (
776
+ i_imagsym is not None and i_realsym is not None
777
+ and i_pointsym is not None):
778
+ results.append(
779
+ _quadpole(t1,
780
+ xm[i_imagsym]['k'], xm[i_realsym]['k'],
781
+ xm[i_pointsym]['k'], s))
782
+ planes.append(Abs(re(t1['a'])))
783
+ # The three additional poles have now been used; to pop them
784
+ # easily we have to do it from the back.
785
+ indices_to_pop = [i_imagsym, i_realsym, i_pointsym]
786
+ indices_to_pop.sort(reverse=True)
787
+ for i in indices_to_pop:
788
+ xm.pop(i)
789
+ elif i_imagsym is not None:
790
+ results.append(_ccpole(t1, xm[i_imagsym]['k'], s))
791
+ planes.append(t1[re])
792
+ xm.pop(i_imagsym)
793
+ elif i_realsym is not None:
794
+ results.append(_rspole(t1, xm[i_realsym]['k'], s))
795
+ planes.append(Abs(t1[re]))
796
+ xm.pop(i_realsym)
797
+ elif i_pointsym is not None:
798
+ results.append(_sypole(t1, xm[i_pointsym]['k'], s))
799
+ planes.append(Abs(t1[re]))
800
+ xm.pop(i_pointsym)
801
+ else:
802
+ results.append(_simplepole(t1, s))
803
+ planes.append(t1[re])
804
+
805
+ return Add(*results), Max(*planes)
806
+
807
+
808
+ def _laplace_rule_trig(fn, t_, s, doit=True, **hints):
809
+ """
810
+ This rule covers trigonometric factors by splitting everything into a
811
+ sum of exponential functions and collecting complex conjugate poles and
812
+ real symmetric poles.
813
+ """
814
+ t = Dummy('t', real=True)
815
+
816
+ if not fn.has(sin, cos, sinh, cosh):
817
+ return None
818
+
819
+ debugf('_laplace_rule_trig: (%s, %s, %s)', (fn, t_, s))
820
+
821
+ f, g = _laplace_trig_split(fn.subs(t_, t))
822
+ debugf(' f = %s\n g = %s', (f, g))
823
+
824
+ xm, xn = _laplace_trig_expsum(f, t)
825
+ debugf(' xm = %s\n xn = %s', (xm, xn))
826
+
827
+ if len(xn) > 0:
828
+ # not implemented yet
829
+ debug(' --> xn is not empty; giving up.')
830
+ return None
831
+
832
+ if not g.has(t):
833
+ r, p = _laplace_trig_ltex(xm, t, s)
834
+ return g*r, p, S.true
835
+ else:
836
+ # Just transform `g` and make frequency-shifted copies
837
+ planes = []
838
+ results = []
839
+ G, G_plane, G_cond = _laplace_transform(g, t, s)
840
+ for x1 in xm:
841
+ results.append(x1['k']*G.subs(s, s-x1['a']))
842
+ planes.append(G_plane+re(x1['a']))
843
+ return Add(*results).subs(t, t_), Max(*planes), G_cond
844
+
845
+
846
+ def _laplace_rule_diff(f, t, s, doit=True, **hints):
847
+ """
848
+ This function looks for derivatives in the time domain and replaces it
849
+ by factors of `s` and initial conditions in the frequency domain. For
850
+ example, if it gets ``(diff(f(t), t), t, s)``, it will compute
851
+ ``s*LaplaceTransform(f(t), t, s) - f(0)``.
852
+ """
853
+
854
+ a = Wild('a', exclude=[t])
855
+ n = Wild('n', exclude=[t])
856
+ g = WildFunction('g')
857
+ ma1 = f.match(a*Derivative(g, (t, n)))
858
+ if ma1 and ma1[n].is_integer:
859
+ m = [z.has(t) for z in ma1[g].args]
860
+ if sum(m) == 1:
861
+ debug('_laplace_apply_rules match:')
862
+ debugf(' f, n: %s, %s', (f, ma1[n]))
863
+ debug(' rule: time derivative (4.1.8)')
864
+ d = []
865
+ for k in range(ma1[n]):
866
+ if k == 0:
867
+ y = ma1[g].subs(t, 0)
868
+ else:
869
+ y = Derivative(ma1[g], (t, k)).subs(t, 0)
870
+ d.append(s**(ma1[n]-k-1)*y)
871
+ r, pr, cr = _laplace_transform(ma1[g], t, s, simplify=False)
872
+ return (ma1[a]*(s**ma1[n]*r - Add(*d)), pr, cr)
873
+ return None
874
+
875
+
876
+ def _laplace_rule_sdiff(f, t, s, doit=True, **hints):
877
+ """
878
+ This function looks for multiplications with polynoimials in `t` as they
879
+ correspond to differentiation in the frequency domain. For example, if it
880
+ gets ``(t*f(t), t, s)``, it will compute
881
+ ``-Derivative(LaplaceTransform(f(t), t, s), s)``.
882
+ """
883
+
884
+ if f.is_Mul:
885
+ pfac = [1]
886
+ ofac = [1]
887
+ for fac in Mul.make_args(f):
888
+ if fac.is_polynomial(t):
889
+ pfac.append(fac)
890
+ else:
891
+ ofac.append(fac)
892
+ if len(pfac) > 1:
893
+ pex = prod(pfac)
894
+ pc = Poly(pex, t).all_coeffs()
895
+ N = len(pc)
896
+ if N > 1:
897
+ debug('_laplace_apply_rules match:')
898
+ debugf(' f, n: %s, %s', (f, pfac))
899
+ debug(' rule: frequency derivative (4.1.6)')
900
+ oex = prod(ofac)
901
+ r_, p_, c_ = _laplace_transform(oex, t, s, simplify=False)
902
+ deri = [r_]
903
+ d1 = False
904
+ try:
905
+ d1 = -diff(deri[-1], s)
906
+ except ValueError:
907
+ d1 = False
908
+ if r_.has(LaplaceTransform):
909
+ for k in range(N-1):
910
+ deri.append((-1)**(k+1)*Derivative(r_, s, k+1))
911
+ else:
912
+ if d1:
913
+ deri.append(d1)
914
+ for k in range(N-2):
915
+ deri.append(-diff(deri[-1], s))
916
+ if d1:
917
+ r = Add(*[pc[N-n-1]*deri[n] for n in range(N)])
918
+ return (r, p_, c_)
919
+ return None
920
+
921
+
922
+ def _laplace_expand(f, t, s, doit=True, **hints):
923
+ """
924
+ This function tries to expand its argument with successively stronger
925
+ methods: first it will expand on the top level, then it will expand any
926
+ multiplications in depth, then it will try all avilable expansion methods,
927
+ and finally it will try to expand trigonometric functions.
928
+
929
+ If it can expand, it will then compute the Laplace transform of the
930
+ expanded term.
931
+ """
932
+
933
+ if f.is_Add:
934
+ return None
935
+ r = expand(f, deep=False)
936
+ if r.is_Add:
937
+ return _laplace_transform(r, t, s, simplify=False)
938
+ r = expand_mul(f)
939
+ if r.is_Add:
940
+ return _laplace_transform(r, t, s, simplify=False)
941
+ r = expand(f)
942
+ if r.is_Add:
943
+ return _laplace_transform(r, t, s, simplify=False)
944
+ if r != f:
945
+ return _laplace_transform(r, t, s, simplify=False)
946
+ r = expand(expand_trig(f))
947
+ if r.is_Add:
948
+ return _laplace_transform(r, t, s, simplify=False)
949
+ return None
950
+
951
+
952
+ def _laplace_apply_prog_rules(f, t, s):
953
+ """
954
+ This function applies all program rules and returns the result if one
955
+ of them gives a result.
956
+ """
957
+
958
+ prog_rules = [_laplace_rule_heaviside, _laplace_rule_delta,
959
+ _laplace_rule_timescale, _laplace_rule_exp,
960
+ _laplace_rule_trig,
961
+ _laplace_rule_diff, _laplace_rule_sdiff]
962
+
963
+ for p_rule in prog_rules:
964
+ if (L := p_rule(f, t, s)) is not None:
965
+ return L
966
+ return None
967
+
968
+
969
+ def _laplace_apply_simple_rules(f, t, s):
970
+ """
971
+ This function applies all simple rules and returns the result if one
972
+ of them gives a result.
973
+ """
974
+ simple_rules, t_, s_ = _laplace_build_rules()
975
+ prep_old = ''
976
+ prep_f = ''
977
+ for t_dom, s_dom, check, plane, prep in simple_rules:
978
+ if prep_old != prep:
979
+ prep_f = prep(f.subs({t: t_}))
980
+ prep_old = prep
981
+ ma = prep_f.match(t_dom)
982
+ if ma:
983
+ try:
984
+ c = check.xreplace(ma)
985
+ except TypeError:
986
+ # This may happen if the time function has imaginary
987
+ # numbers in it. Then we give up.
988
+ continue
989
+ if c == S.true:
990
+ debug('_laplace_apply_simple_rules match:')
991
+ debugf(' f: %s', (f,))
992
+ debugf(' rule: %s o---o %s', (t_dom, s_dom))
993
+ debugf(' match: %s', (ma, ))
994
+ return (s_dom.xreplace(ma).subs({s_: s}),
995
+ plane.xreplace(ma), S.true)
996
+ return None
997
+
998
+
999
+ def _laplace_transform(fn, t_, s_, simplify=True):
1000
+ """
1001
+ Front-end function of the Laplace transform. It tries to apply all known
1002
+ rules recursively, and if everything else fails, it tries to integrate.
1003
+ """
1004
+ debugf('[LT _l_t] (%s, %s, %s)', (fn, t_, s_))
1005
+
1006
+ terms = Add.make_args(fn)
1007
+ terms_s = []
1008
+ planes = []
1009
+ conditions = []
1010
+ for ff in terms:
1011
+ k, ft = ff.as_independent(t_, as_Add=False)
1012
+ if (r := _laplace_apply_simple_rules(ft, t_, s_)) is not None:
1013
+ pass
1014
+ elif (r := _laplace_apply_prog_rules(ft, t_, s_)) is not None:
1015
+ pass
1016
+ elif (r := _laplace_expand(ft, t_, s_)) is not None:
1017
+ pass
1018
+ elif any(undef.has(t_) for undef in ft.atoms(AppliedUndef)):
1019
+ # If there are undefined functions f(t) then integration is
1020
+ # unlikely to do anything useful so we skip it and given an
1021
+ # unevaluated LaplaceTransform.
1022
+ r = (LaplaceTransform(ft, t_, s_), S.NegativeInfinity, True)
1023
+ elif (r := _laplace_transform_integration(
1024
+ ft, t_, s_, simplify=simplify)) is not None:
1025
+ pass
1026
+ else:
1027
+ r = (LaplaceTransform(ft, t_, s_), S.NegativeInfinity, True)
1028
+ (ri_, pi_, ci_) = r
1029
+ terms_s.append(k*ri_)
1030
+ planes.append(pi_)
1031
+ conditions.append(ci_)
1032
+
1033
+ result = Add(*terms_s)
1034
+ if simplify:
1035
+ result = result.simplify(doit=False)
1036
+ plane = Max(*planes)
1037
+ condition = And(*conditions)
1038
+
1039
+ return result, plane, condition
1040
+
1041
+
1042
+ class LaplaceTransform(IntegralTransform):
1043
+ """
1044
+ Class representing unevaluated Laplace transforms.
1045
+
1046
+ For usage of this class, see the :class:`IntegralTransform` docstring.
1047
+
1048
+ For how to compute Laplace transforms, see the :func:`laplace_transform`
1049
+ docstring.
1050
+
1051
+ If this is called with ``.doit()``, it returns the Laplace transform as an
1052
+ expression. If it is called with ``.doit(noconds=False)``, it returns a
1053
+ tuple containing the same expression, a convergence plane, and conditions.
1054
+ """
1055
+
1056
+ _name = 'Laplace'
1057
+
1058
+ def _compute_transform(self, f, t, s, **hints):
1059
+ _simplify = hints.get('simplify', False)
1060
+ LT = _laplace_transform_integration(f, t, s, simplify=_simplify)
1061
+ return LT
1062
+
1063
+ def _as_integral(self, f, t, s):
1064
+ return Integral(f*exp(-s*t), (t, S.Zero, S.Infinity))
1065
+
1066
+ def _collapse_extra(self, extra):
1067
+ conds = []
1068
+ planes = []
1069
+ for plane, cond in extra:
1070
+ conds.append(cond)
1071
+ planes.append(plane)
1072
+ cond = And(*conds)
1073
+ plane = Max(*planes)
1074
+ if cond == S.false:
1075
+ raise IntegralTransformError(
1076
+ 'Laplace', None, 'No combined convergence.')
1077
+ return plane, cond
1078
+
1079
+ def doit(self, **hints):
1080
+ """
1081
+ Try to evaluate the transform in closed form.
1082
+
1083
+ Explanation
1084
+ ===========
1085
+
1086
+ Standard hints are the following:
1087
+ - ``noconds``: if True, do not return convergence conditions. The
1088
+ default setting is `True`.
1089
+ - ``simplify``: if True, it simplifies the final result. The
1090
+ default setting is `False`.
1091
+ """
1092
+ _noconds = hints.get('noconds', True)
1093
+ _simplify = hints.get('simplify', False)
1094
+
1095
+ debugf('[LT doit] (%s, %s, %s)', (self.function,
1096
+ self.function_variable,
1097
+ self.transform_variable))
1098
+
1099
+ t_ = self.function_variable
1100
+ s_ = self.transform_variable
1101
+ fn = self.function
1102
+
1103
+ r = _laplace_transform(fn, t_, s_, simplify=_simplify)
1104
+
1105
+ if _noconds:
1106
+ return r[0]
1107
+ else:
1108
+ return r
1109
+
1110
+
1111
+ def laplace_transform(f, t, s, legacy_matrix=True, **hints):
1112
+ r"""
1113
+ Compute the Laplace Transform `F(s)` of `f(t)`,
1114
+
1115
+ .. math :: F(s) = \int_{0^{-}}^\infty e^{-st} f(t) \mathrm{d}t.
1116
+
1117
+ Explanation
1118
+ ===========
1119
+
1120
+ For all sensible functions, this converges absolutely in a
1121
+ half-plane
1122
+
1123
+ .. math :: a < \operatorname{Re}(s)
1124
+
1125
+ This function returns ``(F, a, cond)`` where ``F`` is the Laplace
1126
+ transform of ``f``, `a` is the half-plane of convergence, and `cond` are
1127
+ auxiliary convergence conditions.
1128
+
1129
+ The implementation is rule-based, and if you are interested in which
1130
+ rules are applied, and whether integration is attempted, you can switch
1131
+ debug information on by setting ``sympy.SYMPY_DEBUG=True``. The numbers
1132
+ of the rules in the debug information (and the code) refer to Bateman's
1133
+ Tables of Integral Transforms [1].
1134
+
1135
+ The lower bound is `0-`, meaning that this bound should be approached
1136
+ from the lower side. This is only necessary if distributions are involved.
1137
+ At present, it is only done if `f(t)` contains ``DiracDelta``, in which
1138
+ case the Laplace transform is computed implicitly as
1139
+
1140
+ .. math ::
1141
+ F(s) = \lim_{\tau\to 0^{-}} \int_{\tau}^\infty e^{-st}
1142
+ f(t) \mathrm{d}t
1143
+
1144
+ by applying rules.
1145
+
1146
+ If the Laplace transform cannot be fully computed in closed form, this
1147
+ function returns expressions containing unevaluated
1148
+ :class:`LaplaceTransform` objects.
1149
+
1150
+ For a description of possible hints, refer to the docstring of
1151
+ :func:`sympy.integrals.transforms.IntegralTransform.doit`. If
1152
+ ``noconds=True``, only `F` will be returned (i.e. not ``cond``, and also
1153
+ not the plane ``a``).
1154
+
1155
+ .. deprecated:: 1.9
1156
+ Legacy behavior for matrices where ``laplace_transform`` with
1157
+ ``noconds=False`` (the default) returns a Matrix whose elements are
1158
+ tuples. The behavior of ``laplace_transform`` for matrices will change
1159
+ in a future release of SymPy to return a tuple of the transformed
1160
+ Matrix and the convergence conditions for the matrix as a whole. Use
1161
+ ``legacy_matrix=False`` to enable the new behavior.
1162
+
1163
+ Examples
1164
+ ========
1165
+
1166
+ >>> from sympy import DiracDelta, exp, laplace_transform
1167
+ >>> from sympy.abc import t, s, a
1168
+ >>> laplace_transform(t**4, t, s)
1169
+ (24/s**5, 0, True)
1170
+ >>> laplace_transform(t**a, t, s)
1171
+ (gamma(a + 1)/(s*s**a), 0, re(a) > -1)
1172
+ >>> laplace_transform(DiracDelta(t)-a*exp(-a*t), t, s, simplify=True)
1173
+ (s/(a + s), -re(a), True)
1174
+
1175
+ References
1176
+ ==========
1177
+
1178
+ .. [1] Erdelyi, A. (ed.), Tables of Integral Transforms, Volume 1,
1179
+ Bateman Manuscript Prooject, McGraw-Hill (1954), available:
1180
+ https://resolver.caltech.edu/CaltechAUTHORS:20140123-101456353
1181
+
1182
+ See Also
1183
+ ========
1184
+
1185
+ inverse_laplace_transform, mellin_transform, fourier_transform
1186
+ hankel_transform, inverse_hankel_transform
1187
+
1188
+ """
1189
+
1190
+ _noconds = hints.get('noconds', False)
1191
+ _simplify = hints.get('simplify', False)
1192
+
1193
+ if isinstance(f, MatrixBase) and hasattr(f, 'applyfunc'):
1194
+
1195
+ conds = not hints.get('noconds', False)
1196
+
1197
+ if conds and legacy_matrix:
1198
+ adt = 'deprecated-laplace-transform-matrix'
1199
+ sympy_deprecation_warning(
1200
+ """
1201
+ Calling laplace_transform() on a Matrix with noconds=False (the default) is
1202
+ deprecated. Either noconds=True or use legacy_matrix=False to get the new
1203
+ behavior.
1204
+ """,
1205
+ deprecated_since_version='1.9',
1206
+ active_deprecations_target=adt,
1207
+ )
1208
+ # Temporarily disable the deprecation warning for non-Expr objects
1209
+ # in Matrix
1210
+ with ignore_warnings(SymPyDeprecationWarning):
1211
+ return f.applyfunc(
1212
+ lambda fij: laplace_transform(fij, t, s, **hints))
1213
+ else:
1214
+ elements_trans = [laplace_transform(
1215
+ fij, t, s, **hints) for fij in f]
1216
+ if conds:
1217
+ elements, avals, conditions = zip(*elements_trans)
1218
+ f_laplace = type(f)(*f.shape, elements)
1219
+ return f_laplace, Max(*avals), And(*conditions)
1220
+ else:
1221
+ return type(f)(*f.shape, elements_trans)
1222
+
1223
+ LT = LaplaceTransform(f, t, s).doit(noconds=False, simplify=_simplify)
1224
+
1225
+ if not _noconds:
1226
+ return LT
1227
+ else:
1228
+ return LT[0]
1229
+
1230
+
1231
+ def _inverse_laplace_transform_integration(F, s, t_, plane, simplify=True):
1232
+ """ The backend function for inverse Laplace transforms. """
1233
+ from sympy.integrals.meijerint import meijerint_inversion, _get_coeff_exp
1234
+ from sympy.integrals.transforms import inverse_mellin_transform
1235
+
1236
+ # There are two strategies we can try:
1237
+ # 1) Use inverse mellin transform, related by a simple change of variables.
1238
+ # 2) Use the inversion integral.
1239
+
1240
+ t = Dummy('t', real=True)
1241
+
1242
+ def pw_simp(*args):
1243
+ """ Simplify a piecewise expression from hyperexpand. """
1244
+ # XXX we break modularity here!
1245
+ if len(args) != 3:
1246
+ return Piecewise(*args)
1247
+ arg = args[2].args[0].argument
1248
+ coeff, exponent = _get_coeff_exp(arg, t)
1249
+ e1 = args[0].args[0]
1250
+ e2 = args[1].args[0]
1251
+ return (
1252
+ Heaviside(1/Abs(coeff) - t**exponent)*e1 +
1253
+ Heaviside(t**exponent - 1/Abs(coeff))*e2)
1254
+
1255
+ if F.is_rational_function(s):
1256
+ F = F.apart(s)
1257
+
1258
+ if F.is_Add:
1259
+ f = Add(
1260
+ *[_inverse_laplace_transform_integration(X, s, t, plane, simplify)
1261
+ for X in F.args])
1262
+ return _simplify(f.subs(t, t_), simplify), True
1263
+
1264
+ try:
1265
+ f, cond = inverse_mellin_transform(F, s, exp(-t), (None, S.Infinity),
1266
+ needeval=True, noconds=False)
1267
+ except IntegralTransformError:
1268
+ f = None
1269
+ if f is None:
1270
+ f = meijerint_inversion(F, s, t)
1271
+ if f is None:
1272
+ return None
1273
+ if f.is_Piecewise:
1274
+ f, cond = f.args[0]
1275
+ if f.has(Integral):
1276
+ return None
1277
+ else:
1278
+ cond = S.true
1279
+ f = f.replace(Piecewise, pw_simp)
1280
+
1281
+ if f.is_Piecewise:
1282
+ # many of the functions called below can't work with piecewise
1283
+ # (b/c it has a bool in args)
1284
+ return f.subs(t, t_), cond
1285
+
1286
+ u = Dummy('u')
1287
+
1288
+ def simp_heaviside(arg, H0=S.Half):
1289
+ a = arg.subs(exp(-t), u)
1290
+ if a.has(t):
1291
+ return Heaviside(arg, H0)
1292
+ from sympy.solvers.inequalities import _solve_inequality
1293
+ rel = _solve_inequality(a > 0, u)
1294
+ if rel.lts == u:
1295
+ k = log(rel.gts)
1296
+ return Heaviside(t + k, H0)
1297
+ else:
1298
+ k = log(rel.lts)
1299
+ return Heaviside(-(t + k), H0)
1300
+
1301
+ f = f.replace(Heaviside, simp_heaviside)
1302
+
1303
+ def simp_exp(arg):
1304
+ return expand_complex(exp(arg))
1305
+
1306
+ f = f.replace(exp, simp_exp)
1307
+
1308
+ # TODO it would be nice to fix cosh and sinh ... simplify messes these
1309
+ # exponentials up
1310
+
1311
+ return _simplify(f.subs(t, t_), simplify), cond
1312
+
1313
+
1314
+ def _complete_the_square_in_denom(f, s):
1315
+ from sympy.simplify.radsimp import fraction
1316
+ [n, d] = fraction(f)
1317
+ if d.is_polynomial(s):
1318
+ cf = d.as_poly(s).all_coeffs()
1319
+ if len(cf) == 3:
1320
+ a, b, c = cf
1321
+ d = a*((s+b/(2*a))**2+c/a-(b/(2*a))**2)
1322
+ return n/d
1323
+
1324
+
1325
+ @cacheit
1326
+ def _inverse_laplace_build_rules():
1327
+ """
1328
+ This is an internal helper function that returns the table of inverse
1329
+ Laplace transform rules in terms of the time variable `t` and the
1330
+ frequency variable `s`. It is used by `_inverse_laplace_apply_rules`.
1331
+ """
1332
+ s = Dummy('s')
1333
+ t = Dummy('t')
1334
+ a = Wild('a', exclude=[s])
1335
+ b = Wild('b', exclude=[s])
1336
+ c = Wild('c', exclude=[s])
1337
+
1338
+ debug('_inverse_laplace_build_rules is building rules')
1339
+
1340
+ def _frac(f, s):
1341
+ try:
1342
+ return f.factor(s)
1343
+ except PolynomialError:
1344
+ return f
1345
+
1346
+ def same(f): return f
1347
+ # This list is sorted according to the prep function needed.
1348
+ _ILT_rules = [
1349
+ (a/s, a, S.true, same, 1),
1350
+ (b*(s+a)**(-c), t**(c-1)*exp(-a*t)/gamma(c), c > 0, same, 1),
1351
+ (1/(s**2+a**2)**2, (sin(a*t) - a*t*cos(a*t))/(2*a**3),
1352
+ S.true, same, 1),
1353
+ # The next two rules must be there in that order. For the second
1354
+ # one, the condition would be a != 0 or, respectively, to take the
1355
+ # limit a -> 0 after the transform if a == 0. It is much simpler if
1356
+ # the case a == 0 has its own rule.
1357
+ (1/(s**b), t**(b - 1)/gamma(b), S.true, same, 1),
1358
+ (1/(s*(s+a)**b), lowergamma(b, a*t)/(a**b*gamma(b)),
1359
+ S.true, same, 1)
1360
+ ]
1361
+ return _ILT_rules, s, t
1362
+
1363
+
1364
+ def _inverse_laplace_apply_simple_rules(f, s, t):
1365
+ """
1366
+ Helper function for the class InverseLaplaceTransform.
1367
+ """
1368
+ if f == 1:
1369
+ debug('_inverse_laplace_apply_simple_rules match:')
1370
+ debugf(' f: %s', (1,))
1371
+ debugf(' rule: 1 o---o DiracDelta(%s)', (t,))
1372
+ return DiracDelta(t), S.true
1373
+
1374
+ _ILT_rules, s_, t_ = _inverse_laplace_build_rules()
1375
+ _prep = ''
1376
+ fsubs = f.subs({s: s_})
1377
+
1378
+ for s_dom, t_dom, check, prep, fac in _ILT_rules:
1379
+ if _prep != (prep, fac):
1380
+ _F = prep(fsubs*fac)
1381
+ _prep = (prep, fac)
1382
+ ma = _F.match(s_dom)
1383
+ if ma:
1384
+ try:
1385
+ c = check.xreplace(ma)
1386
+ except TypeError:
1387
+ continue
1388
+ if c == S.true:
1389
+ debug('_inverse_laplace_apply_simple_rules match:')
1390
+ debugf(' f: %s', (f,))
1391
+ debugf(' rule: %s o---o %s', (s_dom, t_dom))
1392
+ debugf(' ma: %s', (ma,))
1393
+ return Heaviside(t)*t_dom.xreplace(ma).subs({t_: t}), S.true
1394
+
1395
+ return None
1396
+
1397
+
1398
+ def _inverse_laplace_time_shift(F, s, t, plane):
1399
+ """
1400
+ Helper function for the class InverseLaplaceTransform.
1401
+ """
1402
+ a = Wild('a', exclude=[s])
1403
+ g = Wild('g')
1404
+
1405
+ if not F.has(s):
1406
+ return F*DiracDelta(t), S.true
1407
+ ma1 = F.match(exp(a*s))
1408
+ if ma1:
1409
+ if ma1[a].is_negative:
1410
+ debug('_inverse_laplace_time_shift match:')
1411
+ debugf(' f: %s', (F,))
1412
+ debug(' rule: exp(-a*s) o---o DiracDelta(t-a)')
1413
+ debugf(' ma: %s', (ma1,))
1414
+ return DiracDelta(t+ma1[a]), S.true
1415
+ else:
1416
+ debug('_inverse_laplace_time_shift match: negative time shift')
1417
+ return InverseLaplaceTransform(F, s, t, plane), S.true
1418
+
1419
+ ma1 = F.match(exp(a*s)*g)
1420
+ if ma1:
1421
+ if ma1[a].is_negative:
1422
+ debug('_inverse_laplace_time_shift match:')
1423
+ debugf(' f: %s', (F,))
1424
+ debug(' rule: exp(-a*s)*F(s) o---o Heaviside(t-a)*f(t-a)')
1425
+ debugf(' ma: %s', (ma1,))
1426
+ return _inverse_laplace_transform(ma1[g], s, t+ma1[a], plane)
1427
+ else:
1428
+ debug('_inverse_laplace_time_shift match: negative time shift')
1429
+ return InverseLaplaceTransform(F, s, t, plane), S.true
1430
+ return None
1431
+
1432
+
1433
+ def _inverse_laplace_time_diff(F, s, t, plane):
1434
+ """
1435
+ Helper function for the class InverseLaplaceTransform.
1436
+ """
1437
+ n = Wild('n', exclude=[s])
1438
+ g = Wild('g')
1439
+
1440
+ ma1 = F.match(s**n*g)
1441
+ if ma1 and ma1[n].is_integer and ma1[n].is_positive:
1442
+ debug('_inverse_laplace_time_diff match:')
1443
+ debugf(' f: %s', (F,))
1444
+ debug(' rule: s**n*F(s) o---o diff(f(t), t, n)')
1445
+ debugf(' ma: %s', (ma1,))
1446
+ r, c = _inverse_laplace_transform(ma1[g], s, t, plane)
1447
+ r = r.replace(Heaviside(t), 1)
1448
+ if r.has(InverseLaplaceTransform):
1449
+ return diff(r, t, ma1[n]), c
1450
+ else:
1451
+ return Heaviside(t)*diff(r, t, ma1[n]), c
1452
+ return None
1453
+
1454
+
1455
+ def _inverse_laplace_apply_prog_rules(F, s, t, plane):
1456
+ """
1457
+ Helper function for the class InverseLaplaceTransform.
1458
+ """
1459
+ prog_rules = [_inverse_laplace_time_shift,
1460
+ _inverse_laplace_time_diff]
1461
+
1462
+ for p_rule in prog_rules:
1463
+ if (r := p_rule(F, s, t, plane)) is not None:
1464
+ return r
1465
+ return None
1466
+
1467
+
1468
+ def _inverse_laplace_expand(fn, s, t, plane):
1469
+ """
1470
+ Helper function for the class InverseLaplaceTransform.
1471
+ """
1472
+ if fn.is_Add:
1473
+ return None
1474
+ r = expand(fn, deep=False)
1475
+ if r.is_Add:
1476
+ return _inverse_laplace_transform(r, s, t, plane)
1477
+ r = expand_mul(fn)
1478
+ if r.is_Add:
1479
+ return _inverse_laplace_transform(r, s, t, plane)
1480
+ r = expand(fn)
1481
+ if r.is_Add:
1482
+ return _inverse_laplace_transform(r, s, t, plane)
1483
+ if fn.is_rational_function(s):
1484
+ r = fn.apart(s).doit()
1485
+ if r.is_Add:
1486
+ return _inverse_laplace_transform(r, s, t, plane)
1487
+ return None
1488
+
1489
+
1490
+ def _inverse_laplace_rational(fn, s, t, plane, simplify):
1491
+ """
1492
+ Helper function for the class InverseLaplaceTransform.
1493
+ """
1494
+ debugf('[ILT _i_l_r] (%s, %s, %s)', (fn, s, t))
1495
+ x_ = symbols('x_')
1496
+ f = fn.apart(s)
1497
+ terms = Add.make_args(f)
1498
+ terms_t = []
1499
+ conditions = [S.true]
1500
+ for term in terms:
1501
+ [n, d] = term.as_numer_denom()
1502
+ dc = d.as_poly(s).all_coeffs()
1503
+ dc_lead = dc[0]
1504
+ dc = [x/dc_lead for x in dc]
1505
+ nc = [x/dc_lead for x in n.as_poly(s).all_coeffs()]
1506
+ if len(dc) == 1:
1507
+ r = nc[0]*DiracDelta(t)
1508
+ terms_t.append(r)
1509
+ elif len(dc) == 2:
1510
+ r = nc[0]*exp(-dc[1]*t)
1511
+ terms_t.append(Heaviside(t)*r)
1512
+ elif len(dc) == 3:
1513
+ a = dc[1]/2
1514
+ b = (dc[2]-a**2).factor()
1515
+ if len(nc) == 1:
1516
+ nc = [S.Zero] + nc
1517
+ l, m = tuple(nc)
1518
+ if b == 0:
1519
+ r = (m*t+l*(1-a*t))*exp(-a*t)
1520
+ else:
1521
+ hyp = False
1522
+ if b.is_negative:
1523
+ b = -b
1524
+ hyp = True
1525
+ b2 = list(roots(x_**2-b, x_).keys())[0]
1526
+ bs = sqrt(b).simplify()
1527
+ if hyp:
1528
+ r = (
1529
+ l*exp(-a*t)*cosh(b2*t) + (m-a*l) /
1530
+ bs*exp(-a*t)*sinh(bs*t))
1531
+ else:
1532
+ r = l*exp(-a*t)*cos(b2*t) + (m-a*l)/bs*exp(-a*t)*sin(bs*t)
1533
+ terms_t.append(Heaviside(t)*r)
1534
+ else:
1535
+ ft, cond = _inverse_laplace_transform(
1536
+ fn, s, t, plane, simplify=True, dorational=False)
1537
+ terms_t.append(ft)
1538
+ conditions.append(cond)
1539
+
1540
+ result = Add(*terms_t)
1541
+ if simplify:
1542
+ result = result.simplify(doit=False)
1543
+ debugf('[ILT _i_l_r] returns %s', (result,))
1544
+ return result, And(*conditions)
1545
+
1546
+
1547
+ def _inverse_laplace_transform(
1548
+ fn, s_, t_, plane, simplify=True, dorational=True):
1549
+ """
1550
+ Front-end function of the inverse Laplace transform. It tries to apply all
1551
+ known rules recursively. If everything else fails, it tries to integrate.
1552
+ """
1553
+ terms = Add.make_args(fn)
1554
+ terms_t = []
1555
+ conditions = []
1556
+
1557
+ debugf('[ILT _i_l_t] (%s, %s, %s)', (fn, s_, t_))
1558
+
1559
+ for term in terms:
1560
+ k, f = term.as_independent(s_, as_Add=False)
1561
+ if (
1562
+ dorational and term.is_rational_function(s_) and
1563
+ (
1564
+ r := _inverse_laplace_rational(
1565
+ f, s_, t_, plane, simplify)) is not None):
1566
+ pass
1567
+ elif (r := _inverse_laplace_apply_simple_rules(f, s_, t_)) is not None:
1568
+ pass
1569
+ elif (r := _inverse_laplace_expand(f, s_, t_, plane)) is not None:
1570
+ pass
1571
+ elif (
1572
+ (r := _inverse_laplace_apply_prog_rules(f, s_, t_, plane))
1573
+ is not None):
1574
+ pass
1575
+ elif any(undef.has(s_) for undef in f.atoms(AppliedUndef)):
1576
+ # If there are undefined functions f(t) then integration is
1577
+ # unlikely to do anything useful so we skip it and given an
1578
+ # unevaluated LaplaceTransform.
1579
+ r = (InverseLaplaceTransform(f, s_, t_, plane), S.true)
1580
+ elif (
1581
+ r := _inverse_laplace_transform_integration(
1582
+ f, s_, t_, plane, simplify=simplify)) is not None:
1583
+ pass
1584
+ else:
1585
+ r = (InverseLaplaceTransform(f, s_, t_, plane), S.true)
1586
+ (ri_, ci_) = r
1587
+ terms_t.append(k*ri_)
1588
+ conditions.append(ci_)
1589
+
1590
+ result = Add(*terms_t)
1591
+ if simplify:
1592
+ result = result.simplify(doit=False)
1593
+ condition = And(*conditions)
1594
+
1595
+ return result, condition
1596
+
1597
+
1598
+ class InverseLaplaceTransform(IntegralTransform):
1599
+ """
1600
+ Class representing unevaluated inverse Laplace transforms.
1601
+
1602
+ For usage of this class, see the :class:`IntegralTransform` docstring.
1603
+
1604
+ For how to compute inverse Laplace transforms, see the
1605
+ :func:`inverse_laplace_transform` docstring.
1606
+ """
1607
+
1608
+ _name = 'Inverse Laplace'
1609
+ _none_sentinel = Dummy('None')
1610
+ _c = Dummy('c')
1611
+
1612
+ def __new__(cls, F, s, x, plane, **opts):
1613
+ if plane is None:
1614
+ plane = InverseLaplaceTransform._none_sentinel
1615
+ return IntegralTransform.__new__(cls, F, s, x, plane, **opts)
1616
+
1617
+ @property
1618
+ def fundamental_plane(self):
1619
+ plane = self.args[3]
1620
+ if plane is InverseLaplaceTransform._none_sentinel:
1621
+ plane = None
1622
+ return plane
1623
+
1624
+ def _compute_transform(self, F, s, t, **hints):
1625
+ return _inverse_laplace_transform_integration(
1626
+ F, s, t, self.fundamental_plane, **hints)
1627
+
1628
+ def _as_integral(self, F, s, t):
1629
+ c = self.__class__._c
1630
+ return (
1631
+ Integral(exp(s*t)*F, (s, c - S.ImaginaryUnit*S.Infinity,
1632
+ c + S.ImaginaryUnit*S.Infinity)) /
1633
+ (2*S.Pi*S.ImaginaryUnit))
1634
+
1635
+ def doit(self, **hints):
1636
+ """
1637
+ Try to evaluate the transform in closed form.
1638
+
1639
+ Explanation
1640
+ ===========
1641
+
1642
+ Standard hints are the following:
1643
+ - ``noconds``: if True, do not return convergence conditions. The
1644
+ default setting is `True`.
1645
+ - ``simplify``: if True, it simplifies the final result. The
1646
+ default setting is `False`.
1647
+ """
1648
+ _noconds = hints.get('noconds', True)
1649
+ _simplify = hints.get('simplify', False)
1650
+
1651
+ debugf('[ILT doit] (%s, %s, %s)', (self.function,
1652
+ self.function_variable,
1653
+ self.transform_variable))
1654
+
1655
+ s_ = self.function_variable
1656
+ t_ = self.transform_variable
1657
+ fn = self.function
1658
+ plane = self.fundamental_plane
1659
+
1660
+ r = _inverse_laplace_transform(fn, s_, t_, plane, simplify=_simplify)
1661
+
1662
+ if _noconds:
1663
+ return r[0]
1664
+ else:
1665
+ return r
1666
+
1667
+
1668
+ def inverse_laplace_transform(F, s, t, plane=None, **hints):
1669
+ r"""
1670
+ Compute the inverse Laplace transform of `F(s)`, defined as
1671
+
1672
+ .. math ::
1673
+ f(t) = \frac{1}{2\pi i} \int_{c-i\infty}^{c+i\infty} e^{st}
1674
+ F(s) \mathrm{d}s,
1675
+
1676
+ for `c` so large that `F(s)` has no singularites in the
1677
+ half-plane `\operatorname{Re}(s) > c-\epsilon`.
1678
+
1679
+ Explanation
1680
+ ===========
1681
+
1682
+ The plane can be specified by
1683
+ argument ``plane``, but will be inferred if passed as None.
1684
+
1685
+ Under certain regularity conditions, this recovers `f(t)` from its
1686
+ Laplace Transform `F(s)`, for non-negative `t`, and vice
1687
+ versa.
1688
+
1689
+ If the integral cannot be computed in closed form, this function returns
1690
+ an unevaluated :class:`InverseLaplaceTransform` object.
1691
+
1692
+ Note that this function will always assume `t` to be real,
1693
+ regardless of the SymPy assumption on `t`.
1694
+
1695
+ For a description of possible hints, refer to the docstring of
1696
+ :func:`sympy.integrals.transforms.IntegralTransform.doit`.
1697
+
1698
+ Examples
1699
+ ========
1700
+
1701
+ >>> from sympy import inverse_laplace_transform, exp, Symbol
1702
+ >>> from sympy.abc import s, t
1703
+ >>> a = Symbol('a', positive=True)
1704
+ >>> inverse_laplace_transform(exp(-a*s)/s, s, t)
1705
+ Heaviside(-a + t)
1706
+
1707
+ See Also
1708
+ ========
1709
+
1710
+ laplace_transform
1711
+ hankel_transform, inverse_hankel_transform
1712
+ """
1713
+ if isinstance(F, MatrixBase) and hasattr(F, 'applyfunc'):
1714
+ return F.applyfunc(
1715
+ lambda Fij: inverse_laplace_transform(Fij, s, t, plane, **hints))
1716
+ return InverseLaplaceTransform(F, s, t, plane).doit(**hints)
1717
+
1718
+
1719
+ def _fast_inverse_laplace(e, s, t):
1720
+ """Fast inverse Laplace transform of rational function including RootSum"""
1721
+ a, b, n = symbols('a, b, n', cls=Wild, exclude=[s])
1722
+
1723
+ def _ilt(e):
1724
+ if not e.has(s):
1725
+ return e
1726
+ elif e.is_Add:
1727
+ return _ilt_add(e)
1728
+ elif e.is_Mul:
1729
+ return _ilt_mul(e)
1730
+ elif e.is_Pow:
1731
+ return _ilt_pow(e)
1732
+ elif isinstance(e, RootSum):
1733
+ return _ilt_rootsum(e)
1734
+ else:
1735
+ raise NotImplementedError
1736
+
1737
+ def _ilt_add(e):
1738
+ return e.func(*map(_ilt, e.args))
1739
+
1740
+ def _ilt_mul(e):
1741
+ coeff, expr = e.as_independent(s)
1742
+ if expr.is_Mul:
1743
+ raise NotImplementedError
1744
+ return coeff * _ilt(expr)
1745
+
1746
+ def _ilt_pow(e):
1747
+ match = e.match((a*s + b)**n)
1748
+ if match is not None:
1749
+ nm, am, bm = match[n], match[a], match[b]
1750
+ if nm.is_Integer and nm < 0:
1751
+ return t**(-nm-1)*exp(-(bm/am)*t)/(am**-nm*gamma(-nm))
1752
+ if nm == 1:
1753
+ return exp(-(bm/am)*t) / am
1754
+ raise NotImplementedError
1755
+
1756
+ def _ilt_rootsum(e):
1757
+ expr = e.fun.expr
1758
+ [variable] = e.fun.variables
1759
+ return RootSum(e.poly, Lambda(variable, together(_ilt(expr))))
1760
+
1761
+ return _ilt(e)
venv/lib/python3.10/site-packages/sympy/integrals/manualintegrate.py ADDED
@@ -0,0 +1,2171 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """Integration method that emulates by-hand techniques.
2
+
3
+ This module also provides functionality to get the steps used to evaluate a
4
+ particular integral, in the ``integral_steps`` function. This will return
5
+ nested ``Rule`` s representing the integration rules used.
6
+
7
+ Each ``Rule`` class represents a (maybe parametrized) integration rule, e.g.
8
+ ``SinRule`` for integrating ``sin(x)`` and ``ReciprocalSqrtQuadraticRule``
9
+ for integrating ``1/sqrt(a+b*x+c*x**2)``. The ``eval`` method returns the
10
+ integration result.
11
+
12
+ The ``manualintegrate`` function computes the integral by calling ``eval``
13
+ on the rule returned by ``integral_steps``.
14
+
15
+ The integrator can be extended with new heuristics and evaluation
16
+ techniques. To do so, extend the ``Rule`` class, implement ``eval`` method,
17
+ then write a function that accepts an ``IntegralInfo`` object and returns
18
+ either a ``Rule`` instance or ``None``. If the new technique requires a new
19
+ match, add the key and call to the antiderivative function to integral_steps.
20
+ To enable simple substitutions, add the match to find_substitutions.
21
+
22
+ """
23
+
24
+ from __future__ import annotations
25
+ from typing import NamedTuple, Type, Callable, Sequence
26
+ from abc import ABC, abstractmethod
27
+ from dataclasses import dataclass
28
+ from collections import defaultdict
29
+ from collections.abc import Mapping
30
+
31
+ from sympy.core.add import Add
32
+ from sympy.core.cache import cacheit
33
+ from sympy.core.containers import Dict
34
+ from sympy.core.expr import Expr
35
+ from sympy.core.function import Derivative
36
+ from sympy.core.logic import fuzzy_not
37
+ from sympy.core.mul import Mul
38
+ from sympy.core.numbers import Integer, Number, E
39
+ from sympy.core.power import Pow
40
+ from sympy.core.relational import Eq, Ne, Boolean
41
+ from sympy.core.singleton import S
42
+ from sympy.core.symbol import Dummy, Symbol, Wild
43
+ from sympy.functions.elementary.complexes import Abs
44
+ from sympy.functions.elementary.exponential import exp, log
45
+ from sympy.functions.elementary.hyperbolic import (HyperbolicFunction, csch,
46
+ cosh, coth, sech, sinh, tanh, asinh)
47
+ from sympy.functions.elementary.miscellaneous import sqrt
48
+ from sympy.functions.elementary.piecewise import Piecewise
49
+ from sympy.functions.elementary.trigonometric import (TrigonometricFunction,
50
+ cos, sin, tan, cot, csc, sec, acos, asin, atan, acot, acsc, asec)
51
+ from sympy.functions.special.delta_functions import Heaviside, DiracDelta
52
+ from sympy.functions.special.error_functions import (erf, erfi, fresnelc,
53
+ fresnels, Ci, Chi, Si, Shi, Ei, li)
54
+ from sympy.functions.special.gamma_functions import uppergamma
55
+ from sympy.functions.special.elliptic_integrals import elliptic_e, elliptic_f
56
+ from sympy.functions.special.polynomials import (chebyshevt, chebyshevu,
57
+ legendre, hermite, laguerre, assoc_laguerre, gegenbauer, jacobi,
58
+ OrthogonalPolynomial)
59
+ from sympy.functions.special.zeta_functions import polylog
60
+ from .integrals import Integral
61
+ from sympy.logic.boolalg import And
62
+ from sympy.ntheory.factor_ import primefactors
63
+ from sympy.polys.polytools import degree, lcm_list, gcd_list, Poly
64
+ from sympy.simplify.radsimp import fraction
65
+ from sympy.simplify.simplify import simplify
66
+ from sympy.solvers.solvers import solve
67
+ from sympy.strategies.core import switch, do_one, null_safe, condition
68
+ from sympy.utilities.iterables import iterable
69
+ from sympy.utilities.misc import debug
70
+
71
+
72
+ @dataclass
73
+ class Rule(ABC):
74
+ integrand: Expr
75
+ variable: Symbol
76
+
77
+ @abstractmethod
78
+ def eval(self) -> Expr:
79
+ pass
80
+
81
+ @abstractmethod
82
+ def contains_dont_know(self) -> bool:
83
+ pass
84
+
85
+
86
+ @dataclass
87
+ class AtomicRule(Rule, ABC):
88
+ """A simple rule that does not depend on other rules"""
89
+ def contains_dont_know(self) -> bool:
90
+ return False
91
+
92
+
93
+ @dataclass
94
+ class ConstantRule(AtomicRule):
95
+ """integrate(a, x) -> a*x"""
96
+ def eval(self) -> Expr:
97
+ return self.integrand * self.variable
98
+
99
+
100
+ @dataclass
101
+ class ConstantTimesRule(Rule):
102
+ """integrate(a*f(x), x) -> a*integrate(f(x), x)"""
103
+ constant: Expr
104
+ other: Expr
105
+ substep: Rule
106
+
107
+ def eval(self) -> Expr:
108
+ return self.constant * self.substep.eval()
109
+
110
+ def contains_dont_know(self) -> bool:
111
+ return self.substep.contains_dont_know()
112
+
113
+
114
+ @dataclass
115
+ class PowerRule(AtomicRule):
116
+ """integrate(x**a, x)"""
117
+ base: Expr
118
+ exp: Expr
119
+
120
+ def eval(self) -> Expr:
121
+ return Piecewise(
122
+ ((self.base**(self.exp + 1))/(self.exp + 1), Ne(self.exp, -1)),
123
+ (log(self.base), True),
124
+ )
125
+
126
+
127
+ @dataclass
128
+ class NestedPowRule(AtomicRule):
129
+ """integrate((x**a)**b, x)"""
130
+ base: Expr
131
+ exp: Expr
132
+
133
+ def eval(self) -> Expr:
134
+ m = self.base * self.integrand
135
+ return Piecewise((m / (self.exp + 1), Ne(self.exp, -1)),
136
+ (m * log(self.base), True))
137
+
138
+
139
+ @dataclass
140
+ class AddRule(Rule):
141
+ """integrate(f(x) + g(x), x) -> integrate(f(x), x) + integrate(g(x), x)"""
142
+ substeps: list[Rule]
143
+
144
+ def eval(self) -> Expr:
145
+ return Add(*(substep.eval() for substep in self.substeps))
146
+
147
+ def contains_dont_know(self) -> bool:
148
+ return any(substep.contains_dont_know() for substep in self.substeps)
149
+
150
+
151
+ @dataclass
152
+ class URule(Rule):
153
+ """integrate(f(g(x))*g'(x), x) -> integrate(f(u), u), u = g(x)"""
154
+ u_var: Symbol
155
+ u_func: Expr
156
+ substep: Rule
157
+
158
+ def eval(self) -> Expr:
159
+ result = self.substep.eval()
160
+ if self.u_func.is_Pow:
161
+ base, exp_ = self.u_func.as_base_exp()
162
+ if exp_ == -1:
163
+ # avoid needless -log(1/x) from substitution
164
+ result = result.subs(log(self.u_var), -log(base))
165
+ return result.subs(self.u_var, self.u_func)
166
+
167
+ def contains_dont_know(self) -> bool:
168
+ return self.substep.contains_dont_know()
169
+
170
+
171
+ @dataclass
172
+ class PartsRule(Rule):
173
+ """integrate(u(x)*v'(x), x) -> u(x)*v(x) - integrate(u'(x)*v(x), x)"""
174
+ u: Symbol
175
+ dv: Expr
176
+ v_step: Rule
177
+ second_step: Rule | None # None when is a substep of CyclicPartsRule
178
+
179
+ def eval(self) -> Expr:
180
+ assert self.second_step is not None
181
+ v = self.v_step.eval()
182
+ return self.u * v - self.second_step.eval()
183
+
184
+ def contains_dont_know(self) -> bool:
185
+ return self.v_step.contains_dont_know() or (
186
+ self.second_step is not None and self.second_step.contains_dont_know())
187
+
188
+
189
+ @dataclass
190
+ class CyclicPartsRule(Rule):
191
+ """Apply PartsRule multiple times to integrate exp(x)*sin(x)"""
192
+ parts_rules: list[PartsRule]
193
+ coefficient: Expr
194
+
195
+ def eval(self) -> Expr:
196
+ result = []
197
+ sign = 1
198
+ for rule in self.parts_rules:
199
+ result.append(sign * rule.u * rule.v_step.eval())
200
+ sign *= -1
201
+ return Add(*result) / (1 - self.coefficient)
202
+
203
+ def contains_dont_know(self) -> bool:
204
+ return any(substep.contains_dont_know() for substep in self.parts_rules)
205
+
206
+
207
+ @dataclass
208
+ class TrigRule(AtomicRule, ABC):
209
+ pass
210
+
211
+
212
+ @dataclass
213
+ class SinRule(TrigRule):
214
+ """integrate(sin(x), x) -> -cos(x)"""
215
+ def eval(self) -> Expr:
216
+ return -cos(self.variable)
217
+
218
+
219
+ @dataclass
220
+ class CosRule(TrigRule):
221
+ """integrate(cos(x), x) -> sin(x)"""
222
+ def eval(self) -> Expr:
223
+ return sin(self.variable)
224
+
225
+
226
+ @dataclass
227
+ class SecTanRule(TrigRule):
228
+ """integrate(sec(x)*tan(x), x) -> sec(x)"""
229
+ def eval(self) -> Expr:
230
+ return sec(self.variable)
231
+
232
+
233
+ @dataclass
234
+ class CscCotRule(TrigRule):
235
+ """integrate(csc(x)*cot(x), x) -> -csc(x)"""
236
+ def eval(self) -> Expr:
237
+ return -csc(self.variable)
238
+
239
+
240
+ @dataclass
241
+ class Sec2Rule(TrigRule):
242
+ """integrate(sec(x)**2, x) -> tan(x)"""
243
+ def eval(self) -> Expr:
244
+ return tan(self.variable)
245
+
246
+
247
+ @dataclass
248
+ class Csc2Rule(TrigRule):
249
+ """integrate(csc(x)**2, x) -> -cot(x)"""
250
+ def eval(self) -> Expr:
251
+ return -cot(self.variable)
252
+
253
+
254
+ @dataclass
255
+ class HyperbolicRule(AtomicRule, ABC):
256
+ pass
257
+
258
+
259
+ @dataclass
260
+ class SinhRule(HyperbolicRule):
261
+ """integrate(sinh(x), x) -> cosh(x)"""
262
+ def eval(self) -> Expr:
263
+ return cosh(self.variable)
264
+
265
+
266
+ @dataclass
267
+ class CoshRule(HyperbolicRule):
268
+ """integrate(cosh(x), x) -> sinh(x)"""
269
+ def eval(self):
270
+ return sinh(self.variable)
271
+
272
+
273
+ @dataclass
274
+ class ExpRule(AtomicRule):
275
+ """integrate(a**x, x) -> a**x/ln(a)"""
276
+ base: Expr
277
+ exp: Expr
278
+
279
+ def eval(self) -> Expr:
280
+ return self.integrand / log(self.base)
281
+
282
+
283
+ @dataclass
284
+ class ReciprocalRule(AtomicRule):
285
+ """integrate(1/x, x) -> ln(x)"""
286
+ base: Expr
287
+
288
+ def eval(self) -> Expr:
289
+ return log(self.base)
290
+
291
+
292
+ @dataclass
293
+ class ArcsinRule(AtomicRule):
294
+ """integrate(1/sqrt(1-x**2), x) -> asin(x)"""
295
+ def eval(self) -> Expr:
296
+ return asin(self.variable)
297
+
298
+
299
+ @dataclass
300
+ class ArcsinhRule(AtomicRule):
301
+ """integrate(1/sqrt(1+x**2), x) -> asin(x)"""
302
+ def eval(self) -> Expr:
303
+ return asinh(self.variable)
304
+
305
+
306
+ @dataclass
307
+ class ReciprocalSqrtQuadraticRule(AtomicRule):
308
+ """integrate(1/sqrt(a+b*x+c*x**2), x) -> log(2*sqrt(c)*sqrt(a+b*x+c*x**2)+b+2*c*x)/sqrt(c)"""
309
+ a: Expr
310
+ b: Expr
311
+ c: Expr
312
+
313
+ def eval(self) -> Expr:
314
+ a, b, c, x = self.a, self.b, self.c, self.variable
315
+ return log(2*sqrt(c)*sqrt(a+b*x+c*x**2)+b+2*c*x)/sqrt(c)
316
+
317
+
318
+ @dataclass
319
+ class SqrtQuadraticDenomRule(AtomicRule):
320
+ """integrate(poly(x)/sqrt(a+b*x+c*x**2), x)"""
321
+ a: Expr
322
+ b: Expr
323
+ c: Expr
324
+ coeffs: list[Expr]
325
+
326
+ def eval(self) -> Expr:
327
+ a, b, c, coeffs, x = self.a, self.b, self.c, self.coeffs.copy(), self.variable
328
+ # Integrate poly/sqrt(a+b*x+c*x**2) using recursion.
329
+ # coeffs are coefficients of the polynomial.
330
+ # Let I_n = x**n/sqrt(a+b*x+c*x**2), then
331
+ # I_n = A * x**(n-1)*sqrt(a+b*x+c*x**2) - B * I_{n-1} - C * I_{n-2}
332
+ # where A = 1/(n*c), B = (2*n-1)*b/(2*n*c), C = (n-1)*a/(n*c)
333
+ # See https://github.com/sympy/sympy/pull/23608 for proof.
334
+ result_coeffs = []
335
+ coeffs = coeffs.copy()
336
+ for i in range(len(coeffs)-2):
337
+ n = len(coeffs)-1-i
338
+ coeff = coeffs[i]/(c*n)
339
+ result_coeffs.append(coeff)
340
+ coeffs[i+1] -= (2*n-1)*b/2*coeff
341
+ coeffs[i+2] -= (n-1)*a*coeff
342
+ d, e = coeffs[-1], coeffs[-2]
343
+ s = sqrt(a+b*x+c*x**2)
344
+ constant = d-b*e/(2*c)
345
+ if constant == 0:
346
+ I0 = 0
347
+ else:
348
+ step = inverse_trig_rule(IntegralInfo(1/s, x), degenerate=False)
349
+ I0 = constant*step.eval()
350
+ return Add(*(result_coeffs[i]*x**(len(coeffs)-2-i)
351
+ for i in range(len(result_coeffs))), e/c)*s + I0
352
+
353
+
354
+ @dataclass
355
+ class SqrtQuadraticRule(AtomicRule):
356
+ """integrate(sqrt(a+b*x+c*x**2), x)"""
357
+ a: Expr
358
+ b: Expr
359
+ c: Expr
360
+
361
+ def eval(self) -> Expr:
362
+ step = sqrt_quadratic_rule(IntegralInfo(self.integrand, self.variable), degenerate=False)
363
+ return step.eval()
364
+
365
+
366
+ @dataclass
367
+ class AlternativeRule(Rule):
368
+ """Multiple ways to do integration."""
369
+ alternatives: list[Rule]
370
+
371
+ def eval(self) -> Expr:
372
+ return self.alternatives[0].eval()
373
+
374
+ def contains_dont_know(self) -> bool:
375
+ return any(substep.contains_dont_know() for substep in self.alternatives)
376
+
377
+
378
+ @dataclass
379
+ class DontKnowRule(Rule):
380
+ """Leave the integral as is."""
381
+ def eval(self) -> Expr:
382
+ return Integral(self.integrand, self.variable)
383
+
384
+ def contains_dont_know(self) -> bool:
385
+ return True
386
+
387
+
388
+ @dataclass
389
+ class DerivativeRule(AtomicRule):
390
+ """integrate(f'(x), x) -> f(x)"""
391
+ def eval(self) -> Expr:
392
+ assert isinstance(self.integrand, Derivative)
393
+ variable_count = list(self.integrand.variable_count)
394
+ for i, (var, count) in enumerate(variable_count):
395
+ if var == self.variable:
396
+ variable_count[i] = (var, count - 1)
397
+ break
398
+ return Derivative(self.integrand.expr, *variable_count)
399
+
400
+
401
+ @dataclass
402
+ class RewriteRule(Rule):
403
+ """Rewrite integrand to another form that is easier to handle."""
404
+ rewritten: Expr
405
+ substep: Rule
406
+
407
+ def eval(self) -> Expr:
408
+ return self.substep.eval()
409
+
410
+ def contains_dont_know(self) -> bool:
411
+ return self.substep.contains_dont_know()
412
+
413
+
414
+ @dataclass
415
+ class CompleteSquareRule(RewriteRule):
416
+ """Rewrite a+b*x+c*x**2 to a-b**2/(4*c) + c*(x+b/(2*c))**2"""
417
+ pass
418
+
419
+
420
+ @dataclass
421
+ class PiecewiseRule(Rule):
422
+ subfunctions: Sequence[tuple[Rule, bool | Boolean]]
423
+
424
+ def eval(self) -> Expr:
425
+ return Piecewise(*[(substep.eval(), cond)
426
+ for substep, cond in self.subfunctions])
427
+
428
+ def contains_dont_know(self) -> bool:
429
+ return any(substep.contains_dont_know() for substep, _ in self.subfunctions)
430
+
431
+
432
+ @dataclass
433
+ class HeavisideRule(Rule):
434
+ harg: Expr
435
+ ibnd: Expr
436
+ substep: Rule
437
+
438
+ def eval(self) -> Expr:
439
+ # If we are integrating over x and the integrand has the form
440
+ # Heaviside(m*x+b)*g(x) == Heaviside(harg)*g(symbol)
441
+ # then there needs to be continuity at -b/m == ibnd,
442
+ # so we subtract the appropriate term.
443
+ result = self.substep.eval()
444
+ return Heaviside(self.harg) * (result - result.subs(self.variable, self.ibnd))
445
+
446
+ def contains_dont_know(self) -> bool:
447
+ return self.substep.contains_dont_know()
448
+
449
+
450
+ @dataclass
451
+ class DiracDeltaRule(AtomicRule):
452
+ n: Expr
453
+ a: Expr
454
+ b: Expr
455
+
456
+ def eval(self) -> Expr:
457
+ n, a, b, x = self.n, self.a, self.b, self.variable
458
+ if n == 0:
459
+ return Heaviside(a+b*x)/b
460
+ return DiracDelta(a+b*x, n-1)/b
461
+
462
+
463
+ @dataclass
464
+ class TrigSubstitutionRule(Rule):
465
+ theta: Expr
466
+ func: Expr
467
+ rewritten: Expr
468
+ substep: Rule
469
+ restriction: bool | Boolean
470
+
471
+ def eval(self) -> Expr:
472
+ theta, func, x = self.theta, self.func, self.variable
473
+ func = func.subs(sec(theta), 1/cos(theta))
474
+ func = func.subs(csc(theta), 1/sin(theta))
475
+ func = func.subs(cot(theta), 1/tan(theta))
476
+
477
+ trig_function = list(func.find(TrigonometricFunction))
478
+ assert len(trig_function) == 1
479
+ trig_function = trig_function[0]
480
+ relation = solve(x - func, trig_function)
481
+ assert len(relation) == 1
482
+ numer, denom = fraction(relation[0])
483
+
484
+ if isinstance(trig_function, sin):
485
+ opposite = numer
486
+ hypotenuse = denom
487
+ adjacent = sqrt(denom**2 - numer**2)
488
+ inverse = asin(relation[0])
489
+ elif isinstance(trig_function, cos):
490
+ adjacent = numer
491
+ hypotenuse = denom
492
+ opposite = sqrt(denom**2 - numer**2)
493
+ inverse = acos(relation[0])
494
+ else: # tan
495
+ opposite = numer
496
+ adjacent = denom
497
+ hypotenuse = sqrt(denom**2 + numer**2)
498
+ inverse = atan(relation[0])
499
+
500
+ substitution = [
501
+ (sin(theta), opposite/hypotenuse),
502
+ (cos(theta), adjacent/hypotenuse),
503
+ (tan(theta), opposite/adjacent),
504
+ (theta, inverse)
505
+ ]
506
+ return Piecewise(
507
+ (self.substep.eval().subs(substitution).trigsimp(), self.restriction)
508
+ )
509
+
510
+ def contains_dont_know(self) -> bool:
511
+ return self.substep.contains_dont_know()
512
+
513
+
514
+ @dataclass
515
+ class ArctanRule(AtomicRule):
516
+ """integrate(a/(b*x**2+c), x) -> a/b / sqrt(c/b) * atan(x/sqrt(c/b))"""
517
+ a: Expr
518
+ b: Expr
519
+ c: Expr
520
+
521
+ def eval(self) -> Expr:
522
+ a, b, c, x = self.a, self.b, self.c, self.variable
523
+ return a/b / sqrt(c/b) * atan(x/sqrt(c/b))
524
+
525
+
526
+ @dataclass
527
+ class OrthogonalPolyRule(AtomicRule, ABC):
528
+ n: Expr
529
+
530
+
531
+ @dataclass
532
+ class JacobiRule(OrthogonalPolyRule):
533
+ a: Expr
534
+ b: Expr
535
+
536
+ def eval(self) -> Expr:
537
+ n, a, b, x = self.n, self.a, self.b, self.variable
538
+ return Piecewise(
539
+ (2*jacobi(n + 1, a - 1, b - 1, x)/(n + a + b), Ne(n + a + b, 0)),
540
+ (x, Eq(n, 0)),
541
+ ((a + b + 2)*x**2/4 + (a - b)*x/2, Eq(n, 1)))
542
+
543
+
544
+ @dataclass
545
+ class GegenbauerRule(OrthogonalPolyRule):
546
+ a: Expr
547
+
548
+ def eval(self) -> Expr:
549
+ n, a, x = self.n, self.a, self.variable
550
+ return Piecewise(
551
+ (gegenbauer(n + 1, a - 1, x)/(2*(a - 1)), Ne(a, 1)),
552
+ (chebyshevt(n + 1, x)/(n + 1), Ne(n, -1)),
553
+ (S.Zero, True))
554
+
555
+
556
+ @dataclass
557
+ class ChebyshevTRule(OrthogonalPolyRule):
558
+ def eval(self) -> Expr:
559
+ n, x = self.n, self.variable
560
+ return Piecewise(
561
+ ((chebyshevt(n + 1, x)/(n + 1) -
562
+ chebyshevt(n - 1, x)/(n - 1))/2, Ne(Abs(n), 1)),
563
+ (x**2/2, True))
564
+
565
+
566
+ @dataclass
567
+ class ChebyshevURule(OrthogonalPolyRule):
568
+ def eval(self) -> Expr:
569
+ n, x = self.n, self.variable
570
+ return Piecewise(
571
+ (chebyshevt(n + 1, x)/(n + 1), Ne(n, -1)),
572
+ (S.Zero, True))
573
+
574
+
575
+ @dataclass
576
+ class LegendreRule(OrthogonalPolyRule):
577
+ def eval(self) -> Expr:
578
+ n, x = self.n, self.variable
579
+ return(legendre(n + 1, x) - legendre(n - 1, x))/(2*n + 1)
580
+
581
+
582
+ @dataclass
583
+ class HermiteRule(OrthogonalPolyRule):
584
+ def eval(self) -> Expr:
585
+ n, x = self.n, self.variable
586
+ return hermite(n + 1, x)/(2*(n + 1))
587
+
588
+
589
+ @dataclass
590
+ class LaguerreRule(OrthogonalPolyRule):
591
+ def eval(self) -> Expr:
592
+ n, x = self.n, self.variable
593
+ return laguerre(n, x) - laguerre(n + 1, x)
594
+
595
+
596
+ @dataclass
597
+ class AssocLaguerreRule(OrthogonalPolyRule):
598
+ a: Expr
599
+
600
+ def eval(self) -> Expr:
601
+ return -assoc_laguerre(self.n + 1, self.a - 1, self.variable)
602
+
603
+
604
+ @dataclass
605
+ class IRule(AtomicRule, ABC):
606
+ a: Expr
607
+ b: Expr
608
+
609
+
610
+ @dataclass
611
+ class CiRule(IRule):
612
+ def eval(self) -> Expr:
613
+ a, b, x = self.a, self.b, self.variable
614
+ return cos(b)*Ci(a*x) - sin(b)*Si(a*x)
615
+
616
+
617
+ @dataclass
618
+ class ChiRule(IRule):
619
+ def eval(self) -> Expr:
620
+ a, b, x = self.a, self.b, self.variable
621
+ return cosh(b)*Chi(a*x) + sinh(b)*Shi(a*x)
622
+
623
+
624
+ @dataclass
625
+ class EiRule(IRule):
626
+ def eval(self) -> Expr:
627
+ a, b, x = self.a, self.b, self.variable
628
+ return exp(b)*Ei(a*x)
629
+
630
+
631
+ @dataclass
632
+ class SiRule(IRule):
633
+ def eval(self) -> Expr:
634
+ a, b, x = self.a, self.b, self.variable
635
+ return sin(b)*Ci(a*x) + cos(b)*Si(a*x)
636
+
637
+
638
+ @dataclass
639
+ class ShiRule(IRule):
640
+ def eval(self) -> Expr:
641
+ a, b, x = self.a, self.b, self.variable
642
+ return sinh(b)*Chi(a*x) + cosh(b)*Shi(a*x)
643
+
644
+
645
+ @dataclass
646
+ class LiRule(IRule):
647
+ def eval(self) -> Expr:
648
+ a, b, x = self.a, self.b, self.variable
649
+ return li(a*x + b)/a
650
+
651
+
652
+ @dataclass
653
+ class ErfRule(AtomicRule):
654
+ a: Expr
655
+ b: Expr
656
+ c: Expr
657
+
658
+ def eval(self) -> Expr:
659
+ a, b, c, x = self.a, self.b, self.c, self.variable
660
+ if a.is_extended_real:
661
+ return Piecewise(
662
+ (sqrt(S.Pi/(-a))/2 * exp(c - b**2/(4*a)) *
663
+ erf((-2*a*x - b)/(2*sqrt(-a))), a < 0),
664
+ (sqrt(S.Pi/a)/2 * exp(c - b**2/(4*a)) *
665
+ erfi((2*a*x + b)/(2*sqrt(a))), True))
666
+ return sqrt(S.Pi/a)/2 * exp(c - b**2/(4*a)) * \
667
+ erfi((2*a*x + b)/(2*sqrt(a)))
668
+
669
+
670
+ @dataclass
671
+ class FresnelCRule(AtomicRule):
672
+ a: Expr
673
+ b: Expr
674
+ c: Expr
675
+
676
+ def eval(self) -> Expr:
677
+ a, b, c, x = self.a, self.b, self.c, self.variable
678
+ return sqrt(S.Pi/(2*a)) * (
679
+ cos(b**2/(4*a) - c)*fresnelc((2*a*x + b)/sqrt(2*a*S.Pi)) +
680
+ sin(b**2/(4*a) - c)*fresnels((2*a*x + b)/sqrt(2*a*S.Pi)))
681
+
682
+
683
+ @dataclass
684
+ class FresnelSRule(AtomicRule):
685
+ a: Expr
686
+ b: Expr
687
+ c: Expr
688
+
689
+ def eval(self) -> Expr:
690
+ a, b, c, x = self.a, self.b, self.c, self.variable
691
+ return sqrt(S.Pi/(2*a)) * (
692
+ cos(b**2/(4*a) - c)*fresnels((2*a*x + b)/sqrt(2*a*S.Pi)) -
693
+ sin(b**2/(4*a) - c)*fresnelc((2*a*x + b)/sqrt(2*a*S.Pi)))
694
+
695
+
696
+ @dataclass
697
+ class PolylogRule(AtomicRule):
698
+ a: Expr
699
+ b: Expr
700
+
701
+ def eval(self) -> Expr:
702
+ return polylog(self.b + 1, self.a * self.variable)
703
+
704
+
705
+ @dataclass
706
+ class UpperGammaRule(AtomicRule):
707
+ a: Expr
708
+ e: Expr
709
+
710
+ def eval(self) -> Expr:
711
+ a, e, x = self.a, self.e, self.variable
712
+ return x**e * (-a*x)**(-e) * uppergamma(e + 1, -a*x)/a
713
+
714
+
715
+ @dataclass
716
+ class EllipticFRule(AtomicRule):
717
+ a: Expr
718
+ d: Expr
719
+
720
+ def eval(self) -> Expr:
721
+ return elliptic_f(self.variable, self.d/self.a)/sqrt(self.a)
722
+
723
+
724
+ @dataclass
725
+ class EllipticERule(AtomicRule):
726
+ a: Expr
727
+ d: Expr
728
+
729
+ def eval(self) -> Expr:
730
+ return elliptic_e(self.variable, self.d/self.a)*sqrt(self.a)
731
+
732
+
733
+ class IntegralInfo(NamedTuple):
734
+ integrand: Expr
735
+ symbol: Symbol
736
+
737
+
738
+ def manual_diff(f, symbol):
739
+ """Derivative of f in form expected by find_substitutions
740
+
741
+ SymPy's derivatives for some trig functions (like cot) are not in a form
742
+ that works well with finding substitutions; this replaces the
743
+ derivatives for those particular forms with something that works better.
744
+
745
+ """
746
+ if f.args:
747
+ arg = f.args[0]
748
+ if isinstance(f, tan):
749
+ return arg.diff(symbol) * sec(arg)**2
750
+ elif isinstance(f, cot):
751
+ return -arg.diff(symbol) * csc(arg)**2
752
+ elif isinstance(f, sec):
753
+ return arg.diff(symbol) * sec(arg) * tan(arg)
754
+ elif isinstance(f, csc):
755
+ return -arg.diff(symbol) * csc(arg) * cot(arg)
756
+ elif isinstance(f, Add):
757
+ return sum([manual_diff(arg, symbol) for arg in f.args])
758
+ elif isinstance(f, Mul):
759
+ if len(f.args) == 2 and isinstance(f.args[0], Number):
760
+ return f.args[0] * manual_diff(f.args[1], symbol)
761
+ return f.diff(symbol)
762
+
763
+ def manual_subs(expr, *args):
764
+ """
765
+ A wrapper for `expr.subs(*args)` with additional logic for substitution
766
+ of invertible functions.
767
+ """
768
+ if len(args) == 1:
769
+ sequence = args[0]
770
+ if isinstance(sequence, (Dict, Mapping)):
771
+ sequence = sequence.items()
772
+ elif not iterable(sequence):
773
+ raise ValueError("Expected an iterable of (old, new) pairs")
774
+ elif len(args) == 2:
775
+ sequence = [args]
776
+ else:
777
+ raise ValueError("subs accepts either 1 or 2 arguments")
778
+
779
+ new_subs = []
780
+ for old, new in sequence:
781
+ if isinstance(old, log):
782
+ # If log(x) = y, then exp(a*log(x)) = exp(a*y)
783
+ # that is, x**a = exp(a*y). Replace nontrivial powers of x
784
+ # before subs turns them into `exp(y)**a`, but
785
+ # do not replace x itself yet, to avoid `log(exp(y))`.
786
+ x0 = old.args[0]
787
+ expr = expr.replace(lambda x: x.is_Pow and x.base == x0,
788
+ lambda x: exp(x.exp*new))
789
+ new_subs.append((x0, exp(new)))
790
+
791
+ return expr.subs(list(sequence) + new_subs)
792
+
793
+ # Method based on that on SIN, described in "Symbolic Integration: The
794
+ # Stormy Decade"
795
+
796
+ inverse_trig_functions = (atan, asin, acos, acot, acsc, asec)
797
+
798
+
799
+ def find_substitutions(integrand, symbol, u_var):
800
+ results = []
801
+
802
+ def test_subterm(u, u_diff):
803
+ if u_diff == 0:
804
+ return False
805
+ substituted = integrand / u_diff
806
+ debug("substituted: {}, u: {}, u_var: {}".format(substituted, u, u_var))
807
+ substituted = manual_subs(substituted, u, u_var).cancel()
808
+
809
+ if substituted.has_free(symbol):
810
+ return False
811
+ # avoid increasing the degree of a rational function
812
+ if integrand.is_rational_function(symbol) and substituted.is_rational_function(u_var):
813
+ deg_before = max([degree(t, symbol) for t in integrand.as_numer_denom()])
814
+ deg_after = max([degree(t, u_var) for t in substituted.as_numer_denom()])
815
+ if deg_after > deg_before:
816
+ return False
817
+ return substituted.as_independent(u_var, as_Add=False)
818
+
819
+ def exp_subterms(term: Expr):
820
+ linear_coeffs = []
821
+ terms = []
822
+ n = Wild('n', properties=[lambda n: n.is_Integer])
823
+ for exp_ in term.find(exp):
824
+ arg = exp_.args[0]
825
+ if symbol not in arg.free_symbols:
826
+ continue
827
+ match = arg.match(n*symbol)
828
+ if match:
829
+ linear_coeffs.append(match[n])
830
+ else:
831
+ terms.append(exp_)
832
+ if linear_coeffs:
833
+ terms.append(exp(gcd_list(linear_coeffs)*symbol))
834
+ return terms
835
+
836
+ def possible_subterms(term):
837
+ if isinstance(term, (TrigonometricFunction, HyperbolicFunction,
838
+ *inverse_trig_functions,
839
+ exp, log, Heaviside)):
840
+ return [term.args[0]]
841
+ elif isinstance(term, (chebyshevt, chebyshevu,
842
+ legendre, hermite, laguerre)):
843
+ return [term.args[1]]
844
+ elif isinstance(term, (gegenbauer, assoc_laguerre)):
845
+ return [term.args[2]]
846
+ elif isinstance(term, jacobi):
847
+ return [term.args[3]]
848
+ elif isinstance(term, Mul):
849
+ r = []
850
+ for u in term.args:
851
+ r.append(u)
852
+ r.extend(possible_subterms(u))
853
+ return r
854
+ elif isinstance(term, Pow):
855
+ r = [arg for arg in term.args if arg.has(symbol)]
856
+ if term.exp.is_Integer:
857
+ r.extend([term.base**d for d in primefactors(term.exp)
858
+ if 1 < d < abs(term.args[1])])
859
+ if term.base.is_Add:
860
+ r.extend([t for t in possible_subterms(term.base)
861
+ if t.is_Pow])
862
+ return r
863
+ elif isinstance(term, Add):
864
+ r = []
865
+ for arg in term.args:
866
+ r.append(arg)
867
+ r.extend(possible_subterms(arg))
868
+ return r
869
+ return []
870
+
871
+ for u in list(dict.fromkeys(possible_subterms(integrand) + exp_subterms(integrand))):
872
+ if u == symbol:
873
+ continue
874
+ u_diff = manual_diff(u, symbol)
875
+ new_integrand = test_subterm(u, u_diff)
876
+ if new_integrand is not False:
877
+ constant, new_integrand = new_integrand
878
+ if new_integrand == integrand.subs(symbol, u_var):
879
+ continue
880
+ substitution = (u, constant, new_integrand)
881
+ if substitution not in results:
882
+ results.append(substitution)
883
+
884
+ return results
885
+
886
+ def rewriter(condition, rewrite):
887
+ """Strategy that rewrites an integrand."""
888
+ def _rewriter(integral):
889
+ integrand, symbol = integral
890
+ debug("Integral: {} is rewritten with {} on symbol: {}".format(integrand, rewrite, symbol))
891
+ if condition(*integral):
892
+ rewritten = rewrite(*integral)
893
+ if rewritten != integrand:
894
+ substep = integral_steps(rewritten, symbol)
895
+ if not isinstance(substep, DontKnowRule) and substep:
896
+ return RewriteRule(integrand, symbol, rewritten, substep)
897
+ return _rewriter
898
+
899
+ def proxy_rewriter(condition, rewrite):
900
+ """Strategy that rewrites an integrand based on some other criteria."""
901
+ def _proxy_rewriter(criteria):
902
+ criteria, integral = criteria
903
+ integrand, symbol = integral
904
+ debug("Integral: {} is rewritten with {} on symbol: {} and criteria: {}".format(integrand, rewrite, symbol, criteria))
905
+ args = criteria + list(integral)
906
+ if condition(*args):
907
+ rewritten = rewrite(*args)
908
+ if rewritten != integrand:
909
+ return RewriteRule(integrand, symbol, rewritten, integral_steps(rewritten, symbol))
910
+ return _proxy_rewriter
911
+
912
+ def multiplexer(conditions):
913
+ """Apply the rule that matches the condition, else None"""
914
+ def multiplexer_rl(expr):
915
+ for key, rule in conditions.items():
916
+ if key(expr):
917
+ return rule(expr)
918
+ return multiplexer_rl
919
+
920
+ def alternatives(*rules):
921
+ """Strategy that makes an AlternativeRule out of multiple possible results."""
922
+ def _alternatives(integral):
923
+ alts = []
924
+ count = 0
925
+ debug("List of Alternative Rules")
926
+ for rule in rules:
927
+ count = count + 1
928
+ debug("Rule {}: {}".format(count, rule))
929
+
930
+ result = rule(integral)
931
+ if (result and not isinstance(result, DontKnowRule) and
932
+ result != integral and result not in alts):
933
+ alts.append(result)
934
+ if len(alts) == 1:
935
+ return alts[0]
936
+ elif alts:
937
+ doable = [rule for rule in alts if not rule.contains_dont_know()]
938
+ if doable:
939
+ return AlternativeRule(*integral, doable)
940
+ else:
941
+ return AlternativeRule(*integral, alts)
942
+ return _alternatives
943
+
944
+ def constant_rule(integral):
945
+ return ConstantRule(*integral)
946
+
947
+ def power_rule(integral):
948
+ integrand, symbol = integral
949
+ base, expt = integrand.as_base_exp()
950
+
951
+ if symbol not in expt.free_symbols and isinstance(base, Symbol):
952
+ if simplify(expt + 1) == 0:
953
+ return ReciprocalRule(integrand, symbol, base)
954
+ return PowerRule(integrand, symbol, base, expt)
955
+ elif symbol not in base.free_symbols and isinstance(expt, Symbol):
956
+ rule = ExpRule(integrand, symbol, base, expt)
957
+
958
+ if fuzzy_not(log(base).is_zero):
959
+ return rule
960
+ elif log(base).is_zero:
961
+ return ConstantRule(1, symbol)
962
+
963
+ return PiecewiseRule(integrand, symbol, [
964
+ (rule, Ne(log(base), 0)),
965
+ (ConstantRule(1, symbol), True)
966
+ ])
967
+
968
+ def exp_rule(integral):
969
+ integrand, symbol = integral
970
+ if isinstance(integrand.args[0], Symbol):
971
+ return ExpRule(integrand, symbol, E, integrand.args[0])
972
+
973
+
974
+ def orthogonal_poly_rule(integral):
975
+ orthogonal_poly_classes = {
976
+ jacobi: JacobiRule,
977
+ gegenbauer: GegenbauerRule,
978
+ chebyshevt: ChebyshevTRule,
979
+ chebyshevu: ChebyshevURule,
980
+ legendre: LegendreRule,
981
+ hermite: HermiteRule,
982
+ laguerre: LaguerreRule,
983
+ assoc_laguerre: AssocLaguerreRule
984
+ }
985
+ orthogonal_poly_var_index = {
986
+ jacobi: 3,
987
+ gegenbauer: 2,
988
+ assoc_laguerre: 2
989
+ }
990
+ integrand, symbol = integral
991
+ for klass in orthogonal_poly_classes:
992
+ if isinstance(integrand, klass):
993
+ var_index = orthogonal_poly_var_index.get(klass, 1)
994
+ if (integrand.args[var_index] is symbol and not
995
+ any(v.has(symbol) for v in integrand.args[:var_index])):
996
+ return orthogonal_poly_classes[klass](integrand, symbol, *integrand.args[:var_index])
997
+
998
+
999
+ _special_function_patterns: list[tuple[Type, Expr, Callable | None, tuple]] = []
1000
+ _wilds = []
1001
+ _symbol = Dummy('x')
1002
+
1003
+
1004
+ def special_function_rule(integral):
1005
+ integrand, symbol = integral
1006
+ if not _special_function_patterns:
1007
+ a = Wild('a', exclude=[_symbol], properties=[lambda x: not x.is_zero])
1008
+ b = Wild('b', exclude=[_symbol])
1009
+ c = Wild('c', exclude=[_symbol])
1010
+ d = Wild('d', exclude=[_symbol], properties=[lambda x: not x.is_zero])
1011
+ e = Wild('e', exclude=[_symbol], properties=[
1012
+ lambda x: not (x.is_nonnegative and x.is_integer)])
1013
+ _wilds.extend((a, b, c, d, e))
1014
+ # patterns consist of a SymPy class, a wildcard expr, an optional
1015
+ # condition coded as a lambda (when Wild properties are not enough),
1016
+ # followed by an applicable rule
1017
+ linear_pattern = a*_symbol + b
1018
+ quadratic_pattern = a*_symbol**2 + b*_symbol + c
1019
+ _special_function_patterns.extend((
1020
+ (Mul, exp(linear_pattern, evaluate=False)/_symbol, None, EiRule),
1021
+ (Mul, cos(linear_pattern, evaluate=False)/_symbol, None, CiRule),
1022
+ (Mul, cosh(linear_pattern, evaluate=False)/_symbol, None, ChiRule),
1023
+ (Mul, sin(linear_pattern, evaluate=False)/_symbol, None, SiRule),
1024
+ (Mul, sinh(linear_pattern, evaluate=False)/_symbol, None, ShiRule),
1025
+ (Pow, 1/log(linear_pattern, evaluate=False), None, LiRule),
1026
+ (exp, exp(quadratic_pattern, evaluate=False), None, ErfRule),
1027
+ (sin, sin(quadratic_pattern, evaluate=False), None, FresnelSRule),
1028
+ (cos, cos(quadratic_pattern, evaluate=False), None, FresnelCRule),
1029
+ (Mul, _symbol**e*exp(a*_symbol, evaluate=False), None, UpperGammaRule),
1030
+ (Mul, polylog(b, a*_symbol, evaluate=False)/_symbol, None, PolylogRule),
1031
+ (Pow, 1/sqrt(a - d*sin(_symbol, evaluate=False)**2),
1032
+ lambda a, d: a != d, EllipticFRule),
1033
+ (Pow, sqrt(a - d*sin(_symbol, evaluate=False)**2),
1034
+ lambda a, d: a != d, EllipticERule),
1035
+ ))
1036
+ _integrand = integrand.subs(symbol, _symbol)
1037
+ for type_, pattern, constraint, rule in _special_function_patterns:
1038
+ if isinstance(_integrand, type_):
1039
+ match = _integrand.match(pattern)
1040
+ if match:
1041
+ wild_vals = tuple(match.get(w) for w in _wilds
1042
+ if match.get(w) is not None)
1043
+ if constraint is None or constraint(*wild_vals):
1044
+ return rule(integrand, symbol, *wild_vals)
1045
+
1046
+
1047
+ def _add_degenerate_step(generic_cond, generic_step: Rule, degenerate_step: Rule | None) -> Rule:
1048
+ if degenerate_step is None:
1049
+ return generic_step
1050
+ if isinstance(generic_step, PiecewiseRule):
1051
+ subfunctions = [(substep, (cond & generic_cond).simplify())
1052
+ for substep, cond in generic_step.subfunctions]
1053
+ else:
1054
+ subfunctions = [(generic_step, generic_cond)]
1055
+ if isinstance(degenerate_step, PiecewiseRule):
1056
+ subfunctions += degenerate_step.subfunctions
1057
+ else:
1058
+ subfunctions.append((degenerate_step, S.true))
1059
+ return PiecewiseRule(generic_step.integrand, generic_step.variable, subfunctions)
1060
+
1061
+
1062
+ def nested_pow_rule(integral: IntegralInfo):
1063
+ # nested (c*(a+b*x)**d)**e
1064
+ integrand, x = integral
1065
+
1066
+ a_ = Wild('a', exclude=[x])
1067
+ b_ = Wild('b', exclude=[x, 0])
1068
+ pattern = a_+b_*x
1069
+ generic_cond = S.true
1070
+
1071
+ class NoMatch(Exception):
1072
+ pass
1073
+
1074
+ def _get_base_exp(expr: Expr) -> tuple[Expr, Expr]:
1075
+ if not expr.has_free(x):
1076
+ return S.One, S.Zero
1077
+ if expr.is_Mul:
1078
+ _, terms = expr.as_coeff_mul()
1079
+ if not terms:
1080
+ return S.One, S.Zero
1081
+ results = [_get_base_exp(term) for term in terms]
1082
+ bases = {b for b, _ in results}
1083
+ bases.discard(S.One)
1084
+ if len(bases) == 1:
1085
+ return bases.pop(), Add(*(e for _, e in results))
1086
+ raise NoMatch
1087
+ if expr.is_Pow:
1088
+ b, e = expr.base, expr.exp # type: ignore
1089
+ if e.has_free(x):
1090
+ raise NoMatch
1091
+ base_, sub_exp = _get_base_exp(b)
1092
+ return base_, sub_exp * e
1093
+ match = expr.match(pattern)
1094
+ if match:
1095
+ a, b = match[a_], match[b_]
1096
+ base_ = x + a/b
1097
+ nonlocal generic_cond
1098
+ generic_cond = Ne(b, 0)
1099
+ return base_, S.One
1100
+ raise NoMatch
1101
+
1102
+ try:
1103
+ base, exp_ = _get_base_exp(integrand)
1104
+ except NoMatch:
1105
+ return
1106
+ if generic_cond is S.true:
1107
+ degenerate_step = None
1108
+ else:
1109
+ # equivalent with subs(b, 0) but no need to find b
1110
+ degenerate_step = ConstantRule(integrand.subs(x, 0), x)
1111
+ generic_step = NestedPowRule(integrand, x, base, exp_)
1112
+ return _add_degenerate_step(generic_cond, generic_step, degenerate_step)
1113
+
1114
+
1115
+ def inverse_trig_rule(integral: IntegralInfo, degenerate=True):
1116
+ """
1117
+ Set degenerate=False on recursive call where coefficient of quadratic term
1118
+ is assumed non-zero.
1119
+ """
1120
+ integrand, symbol = integral
1121
+ base, exp = integrand.as_base_exp()
1122
+ a = Wild('a', exclude=[symbol])
1123
+ b = Wild('b', exclude=[symbol])
1124
+ c = Wild('c', exclude=[symbol, 0])
1125
+ match = base.match(a + b*symbol + c*symbol**2)
1126
+
1127
+ if not match:
1128
+ return
1129
+
1130
+ def make_inverse_trig(RuleClass, a, sign_a, c, sign_c, h) -> Rule:
1131
+ u_var = Dummy("u")
1132
+ rewritten = 1/sqrt(sign_a*a + sign_c*c*(symbol-h)**2) # a>0, c>0
1133
+ quadratic_base = sqrt(c/a)*(symbol-h)
1134
+ constant = 1/sqrt(c)
1135
+ u_func = None
1136
+ if quadratic_base is not symbol:
1137
+ u_func = quadratic_base
1138
+ quadratic_base = u_var
1139
+ standard_form = 1/sqrt(sign_a + sign_c*quadratic_base**2)
1140
+ substep = RuleClass(standard_form, quadratic_base)
1141
+ if constant != 1:
1142
+ substep = ConstantTimesRule(constant*standard_form, symbol, constant, standard_form, substep)
1143
+ if u_func is not None:
1144
+ substep = URule(rewritten, symbol, u_var, u_func, substep)
1145
+ if h != 0:
1146
+ substep = CompleteSquareRule(integrand, symbol, rewritten, substep)
1147
+ return substep
1148
+
1149
+ a, b, c = [match.get(i, S.Zero) for i in (a, b, c)]
1150
+ generic_cond = Ne(c, 0)
1151
+ if not degenerate or generic_cond is S.true:
1152
+ degenerate_step = None
1153
+ elif b.is_zero:
1154
+ degenerate_step = ConstantRule(a ** exp, symbol)
1155
+ else:
1156
+ degenerate_step = sqrt_linear_rule(IntegralInfo((a + b * symbol) ** exp, symbol))
1157
+
1158
+ if simplify(2*exp + 1) == 0:
1159
+ h, k = -b/(2*c), a - b**2/(4*c) # rewrite base to k + c*(symbol-h)**2
1160
+ non_square_cond = Ne(k, 0)
1161
+ square_step = None
1162
+ if non_square_cond is not S.true:
1163
+ square_step = NestedPowRule(1/sqrt(c*(symbol-h)**2), symbol, symbol-h, S.NegativeOne)
1164
+ if non_square_cond is S.false:
1165
+ return square_step
1166
+ generic_step = ReciprocalSqrtQuadraticRule(integrand, symbol, a, b, c)
1167
+ step = _add_degenerate_step(non_square_cond, generic_step, square_step)
1168
+ if k.is_real and c.is_real:
1169
+ # list of ((rule, base_exp, a, sign_a, b, sign_b), condition)
1170
+ rules = []
1171
+ for args, cond in ( # don't apply ArccoshRule to x**2-1
1172
+ ((ArcsinRule, k, 1, -c, -1, h), And(k > 0, c < 0)), # 1-x**2
1173
+ ((ArcsinhRule, k, 1, c, 1, h), And(k > 0, c > 0)), # 1+x**2
1174
+ ):
1175
+ if cond is S.true:
1176
+ return make_inverse_trig(*args)
1177
+ if cond is not S.false:
1178
+ rules.append((make_inverse_trig(*args), cond))
1179
+ if rules:
1180
+ if not k.is_positive: # conditions are not thorough, need fall back rule
1181
+ rules.append((generic_step, S.true))
1182
+ step = PiecewiseRule(integrand, symbol, rules)
1183
+ else:
1184
+ step = generic_step
1185
+ return _add_degenerate_step(generic_cond, step, degenerate_step)
1186
+ if exp == S.Half:
1187
+ step = SqrtQuadraticRule(integrand, symbol, a, b, c)
1188
+ return _add_degenerate_step(generic_cond, step, degenerate_step)
1189
+
1190
+
1191
+ def add_rule(integral):
1192
+ integrand, symbol = integral
1193
+ results = [integral_steps(g, symbol)
1194
+ for g in integrand.as_ordered_terms()]
1195
+ return None if None in results else AddRule(integrand, symbol, results)
1196
+
1197
+
1198
+ def mul_rule(integral: IntegralInfo):
1199
+ integrand, symbol = integral
1200
+
1201
+ # Constant times function case
1202
+ coeff, f = integrand.as_independent(symbol)
1203
+ if coeff != 1:
1204
+ next_step = integral_steps(f, symbol)
1205
+ if next_step is not None:
1206
+ return ConstantTimesRule(integrand, symbol, coeff, f, next_step)
1207
+
1208
+
1209
+ def _parts_rule(integrand, symbol) -> tuple[Expr, Expr, Expr, Expr, Rule] | None:
1210
+ # LIATE rule:
1211
+ # log, inverse trig, algebraic, trigonometric, exponential
1212
+ def pull_out_algebraic(integrand):
1213
+ integrand = integrand.cancel().together()
1214
+ # iterating over Piecewise args would not work here
1215
+ algebraic = ([] if isinstance(integrand, Piecewise) or not integrand.is_Mul
1216
+ else [arg for arg in integrand.args if arg.is_algebraic_expr(symbol)])
1217
+ if algebraic:
1218
+ u = Mul(*algebraic)
1219
+ dv = (integrand / u).cancel()
1220
+ return u, dv
1221
+
1222
+ def pull_out_u(*functions) -> Callable[[Expr], tuple[Expr, Expr] | None]:
1223
+ def pull_out_u_rl(integrand: Expr) -> tuple[Expr, Expr] | None:
1224
+ if any(integrand.has(f) for f in functions):
1225
+ args = [arg for arg in integrand.args
1226
+ if any(isinstance(arg, cls) for cls in functions)]
1227
+ if args:
1228
+ u = Mul(*args)
1229
+ dv = integrand / u
1230
+ return u, dv
1231
+ return None
1232
+
1233
+ return pull_out_u_rl
1234
+
1235
+ liate_rules = [pull_out_u(log), pull_out_u(*inverse_trig_functions),
1236
+ pull_out_algebraic, pull_out_u(sin, cos),
1237
+ pull_out_u(exp)]
1238
+
1239
+
1240
+ dummy = Dummy("temporary")
1241
+ # we can integrate log(x) and atan(x) by setting dv = 1
1242
+ if isinstance(integrand, (log, *inverse_trig_functions)):
1243
+ integrand = dummy * integrand
1244
+
1245
+ for index, rule in enumerate(liate_rules):
1246
+ result = rule(integrand)
1247
+
1248
+ if result:
1249
+ u, dv = result
1250
+
1251
+ # Don't pick u to be a constant if possible
1252
+ if symbol not in u.free_symbols and not u.has(dummy):
1253
+ return None
1254
+
1255
+ u = u.subs(dummy, 1)
1256
+ dv = dv.subs(dummy, 1)
1257
+
1258
+ # Don't pick a non-polynomial algebraic to be differentiated
1259
+ if rule == pull_out_algebraic and not u.is_polynomial(symbol):
1260
+ return None
1261
+ # Don't trade one logarithm for another
1262
+ if isinstance(u, log):
1263
+ rec_dv = 1/dv
1264
+ if (rec_dv.is_polynomial(symbol) and
1265
+ degree(rec_dv, symbol) == 1):
1266
+ return None
1267
+
1268
+ # Can integrate a polynomial times OrthogonalPolynomial
1269
+ if rule == pull_out_algebraic:
1270
+ if dv.is_Derivative or dv.has(TrigonometricFunction) or \
1271
+ isinstance(dv, OrthogonalPolynomial):
1272
+ v_step = integral_steps(dv, symbol)
1273
+ if v_step.contains_dont_know():
1274
+ return None
1275
+ else:
1276
+ du = u.diff(symbol)
1277
+ v = v_step.eval()
1278
+ return u, dv, v, du, v_step
1279
+
1280
+ # make sure dv is amenable to integration
1281
+ accept = False
1282
+ if index < 2: # log and inverse trig are usually worth trying
1283
+ accept = True
1284
+ elif (rule == pull_out_algebraic and dv.args and
1285
+ all(isinstance(a, (sin, cos, exp))
1286
+ for a in dv.args)):
1287
+ accept = True
1288
+ else:
1289
+ for lrule in liate_rules[index + 1:]:
1290
+ r = lrule(integrand)
1291
+ if r and r[0].subs(dummy, 1).equals(dv):
1292
+ accept = True
1293
+ break
1294
+
1295
+ if accept:
1296
+ du = u.diff(symbol)
1297
+ v_step = integral_steps(simplify(dv), symbol)
1298
+ if not v_step.contains_dont_know():
1299
+ v = v_step.eval()
1300
+ return u, dv, v, du, v_step
1301
+ return None
1302
+
1303
+
1304
+ def parts_rule(integral):
1305
+ integrand, symbol = integral
1306
+ constant, integrand = integrand.as_coeff_Mul()
1307
+
1308
+ result = _parts_rule(integrand, symbol)
1309
+
1310
+ steps = []
1311
+ if result:
1312
+ u, dv, v, du, v_step = result
1313
+ debug("u : {}, dv : {}, v : {}, du : {}, v_step: {}".format(u, dv, v, du, v_step))
1314
+ steps.append(result)
1315
+
1316
+ if isinstance(v, Integral):
1317
+ return
1318
+
1319
+ # Set a limit on the number of times u can be used
1320
+ if isinstance(u, (sin, cos, exp, sinh, cosh)):
1321
+ cachekey = u.xreplace({symbol: _cache_dummy})
1322
+ if _parts_u_cache[cachekey] > 2:
1323
+ return
1324
+ _parts_u_cache[cachekey] += 1
1325
+
1326
+ # Try cyclic integration by parts a few times
1327
+ for _ in range(4):
1328
+ debug("Cyclic integration {} with v: {}, du: {}, integrand: {}".format(_, v, du, integrand))
1329
+ coefficient = ((v * du) / integrand).cancel()
1330
+ if coefficient == 1:
1331
+ break
1332
+ if symbol not in coefficient.free_symbols:
1333
+ rule = CyclicPartsRule(integrand, symbol,
1334
+ [PartsRule(None, None, u, dv, v_step, None)
1335
+ for (u, dv, v, du, v_step) in steps],
1336
+ (-1) ** len(steps) * coefficient)
1337
+ if (constant != 1) and rule:
1338
+ rule = ConstantTimesRule(constant * integrand, symbol, constant, integrand, rule)
1339
+ return rule
1340
+
1341
+ # _parts_rule is sensitive to constants, factor it out
1342
+ next_constant, next_integrand = (v * du).as_coeff_Mul()
1343
+ result = _parts_rule(next_integrand, symbol)
1344
+
1345
+ if result:
1346
+ u, dv, v, du, v_step = result
1347
+ u *= next_constant
1348
+ du *= next_constant
1349
+ steps.append((u, dv, v, du, v_step))
1350
+ else:
1351
+ break
1352
+
1353
+ def make_second_step(steps, integrand):
1354
+ if steps:
1355
+ u, dv, v, du, v_step = steps[0]
1356
+ return PartsRule(integrand, symbol, u, dv, v_step, make_second_step(steps[1:], v * du))
1357
+ return integral_steps(integrand, symbol)
1358
+
1359
+ if steps:
1360
+ u, dv, v, du, v_step = steps[0]
1361
+ rule = PartsRule(integrand, symbol, u, dv, v_step, make_second_step(steps[1:], v * du))
1362
+ if (constant != 1) and rule:
1363
+ rule = ConstantTimesRule(constant * integrand, symbol, constant, integrand, rule)
1364
+ return rule
1365
+
1366
+
1367
+ def trig_rule(integral):
1368
+ integrand, symbol = integral
1369
+ if integrand == sin(symbol):
1370
+ return SinRule(integrand, symbol)
1371
+ if integrand == cos(symbol):
1372
+ return CosRule(integrand, symbol)
1373
+ if integrand == sec(symbol)**2:
1374
+ return Sec2Rule(integrand, symbol)
1375
+ if integrand == csc(symbol)**2:
1376
+ return Csc2Rule(integrand, symbol)
1377
+
1378
+ if isinstance(integrand, tan):
1379
+ rewritten = sin(*integrand.args) / cos(*integrand.args)
1380
+ elif isinstance(integrand, cot):
1381
+ rewritten = cos(*integrand.args) / sin(*integrand.args)
1382
+ elif isinstance(integrand, sec):
1383
+ arg = integrand.args[0]
1384
+ rewritten = ((sec(arg)**2 + tan(arg) * sec(arg)) /
1385
+ (sec(arg) + tan(arg)))
1386
+ elif isinstance(integrand, csc):
1387
+ arg = integrand.args[0]
1388
+ rewritten = ((csc(arg)**2 + cot(arg) * csc(arg)) /
1389
+ (csc(arg) + cot(arg)))
1390
+ else:
1391
+ return
1392
+
1393
+ return RewriteRule(integrand, symbol, rewritten, integral_steps(rewritten, symbol))
1394
+
1395
+ def trig_product_rule(integral: IntegralInfo):
1396
+ integrand, symbol = integral
1397
+ if integrand == sec(symbol) * tan(symbol):
1398
+ return SecTanRule(integrand, symbol)
1399
+ if integrand == csc(symbol) * cot(symbol):
1400
+ return CscCotRule(integrand, symbol)
1401
+
1402
+
1403
+ def quadratic_denom_rule(integral):
1404
+ integrand, symbol = integral
1405
+ a = Wild('a', exclude=[symbol])
1406
+ b = Wild('b', exclude=[symbol])
1407
+ c = Wild('c', exclude=[symbol])
1408
+
1409
+ match = integrand.match(a / (b * symbol ** 2 + c))
1410
+
1411
+ if match:
1412
+ a, b, c = match[a], match[b], match[c]
1413
+ general_rule = ArctanRule(integrand, symbol, a, b, c)
1414
+ if b.is_extended_real and c.is_extended_real:
1415
+ positive_cond = c/b > 0
1416
+ if positive_cond is S.true:
1417
+ return general_rule
1418
+ coeff = a/(2*sqrt(-c)*sqrt(b))
1419
+ constant = sqrt(-c/b)
1420
+ r1 = 1/(symbol-constant)
1421
+ r2 = 1/(symbol+constant)
1422
+ log_steps = [ReciprocalRule(r1, symbol, symbol-constant),
1423
+ ConstantTimesRule(-r2, symbol, -1, r2, ReciprocalRule(r2, symbol, symbol+constant))]
1424
+ rewritten = sub = r1 - r2
1425
+ negative_step = AddRule(sub, symbol, log_steps)
1426
+ if coeff != 1:
1427
+ rewritten = Mul(coeff, sub, evaluate=False)
1428
+ negative_step = ConstantTimesRule(rewritten, symbol, coeff, sub, negative_step)
1429
+ negative_step = RewriteRule(integrand, symbol, rewritten, negative_step)
1430
+ if positive_cond is S.false:
1431
+ return negative_step
1432
+ return PiecewiseRule(integrand, symbol, [(general_rule, positive_cond), (negative_step, S.true)])
1433
+ return general_rule
1434
+
1435
+ d = Wild('d', exclude=[symbol])
1436
+ match2 = integrand.match(a / (b * symbol ** 2 + c * symbol + d))
1437
+ if match2:
1438
+ b, c = match2[b], match2[c]
1439
+ if b.is_zero:
1440
+ return
1441
+ u = Dummy('u')
1442
+ u_func = symbol + c/(2*b)
1443
+ integrand2 = integrand.subs(symbol, u - c / (2*b))
1444
+ next_step = integral_steps(integrand2, u)
1445
+ if next_step:
1446
+ return URule(integrand2, symbol, u, u_func, next_step)
1447
+ else:
1448
+ return
1449
+ e = Wild('e', exclude=[symbol])
1450
+ match3 = integrand.match((a* symbol + b) / (c * symbol ** 2 + d * symbol + e))
1451
+ if match3:
1452
+ a, b, c, d, e = match3[a], match3[b], match3[c], match3[d], match3[e]
1453
+ if c.is_zero:
1454
+ return
1455
+ denominator = c * symbol**2 + d * symbol + e
1456
+ const = a/(2*c)
1457
+ numer1 = (2*c*symbol+d)
1458
+ numer2 = - const*d + b
1459
+ u = Dummy('u')
1460
+ step1 = URule(integrand, symbol,
1461
+ u, denominator, integral_steps(u**(-1), u))
1462
+ if const != 1:
1463
+ step1 = ConstantTimesRule(const*numer1/denominator, symbol,
1464
+ const, numer1/denominator, step1)
1465
+ if numer2.is_zero:
1466
+ return step1
1467
+ step2 = integral_steps(numer2/denominator, symbol)
1468
+ substeps = AddRule(integrand, symbol, [step1, step2])
1469
+ rewriten = const*numer1/denominator+numer2/denominator
1470
+ return RewriteRule(integrand, symbol, rewriten, substeps)
1471
+
1472
+ return
1473
+
1474
+
1475
+ def sqrt_linear_rule(integral: IntegralInfo):
1476
+ """
1477
+ Substitute common (a+b*x)**(1/n)
1478
+ """
1479
+ integrand, x = integral
1480
+ a = Wild('a', exclude=[x])
1481
+ b = Wild('b', exclude=[x, 0])
1482
+ a0 = b0 = 0
1483
+ bases, qs, bs = [], [], []
1484
+ for pow_ in integrand.find(Pow): # collect all (a+b*x)**(p/q)
1485
+ base, exp_ = pow_.base, pow_.exp
1486
+ if exp_.is_Integer or x not in base.free_symbols: # skip 1/x and sqrt(2)
1487
+ continue
1488
+ if not exp_.is_Rational: # exclude x**pi
1489
+ return
1490
+ match = base.match(a+b*x)
1491
+ if not match: # skip non-linear
1492
+ continue # for sqrt(x+sqrt(x)), although base is non-linear, we can still substitute sqrt(x)
1493
+ a1, b1 = match[a], match[b]
1494
+ if a0*b1 != a1*b0 or not (b0/b1).is_nonnegative: # cannot transform sqrt(x) to sqrt(x+1) or sqrt(-x)
1495
+ return
1496
+ if b0 == 0 or (b0/b1 > 1) is S.true: # choose the latter of sqrt(2*x) and sqrt(x) as representative
1497
+ a0, b0 = a1, b1
1498
+ bases.append(base)
1499
+ bs.append(b1)
1500
+ qs.append(exp_.q)
1501
+ if b0 == 0: # no such pattern found
1502
+ return
1503
+ q0: Integer = lcm_list(qs)
1504
+ u_x = (a0 + b0*x)**(1/q0)
1505
+ u = Dummy("u")
1506
+ substituted = integrand.subs({base**(S.One/q): (b/b0)**(S.One/q)*u**(q0/q)
1507
+ for base, b, q in zip(bases, bs, qs)}).subs(x, (u**q0-a0)/b0)
1508
+ substep = integral_steps(substituted*u**(q0-1)*q0/b0, u)
1509
+ if not substep.contains_dont_know():
1510
+ step: Rule = URule(integrand, x, u, u_x, substep)
1511
+ generic_cond = Ne(b0, 0)
1512
+ if generic_cond is not S.true: # possible degenerate case
1513
+ simplified = integrand.subs({b: 0 for b in bs})
1514
+ degenerate_step = integral_steps(simplified, x)
1515
+ step = PiecewiseRule(integrand, x, [(step, generic_cond), (degenerate_step, S.true)])
1516
+ return step
1517
+
1518
+
1519
+ def sqrt_quadratic_rule(integral: IntegralInfo, degenerate=True):
1520
+ integrand, x = integral
1521
+ a = Wild('a', exclude=[x])
1522
+ b = Wild('b', exclude=[x])
1523
+ c = Wild('c', exclude=[x, 0])
1524
+ f = Wild('f')
1525
+ n = Wild('n', properties=[lambda n: n.is_Integer and n.is_odd])
1526
+ match = integrand.match(f*sqrt(a+b*x+c*x**2)**n)
1527
+ if not match:
1528
+ return
1529
+ a, b, c, f, n = match[a], match[b], match[c], match[f], match[n]
1530
+ f_poly = f.as_poly(x)
1531
+ if f_poly is None:
1532
+ return
1533
+
1534
+ generic_cond = Ne(c, 0)
1535
+ if not degenerate or generic_cond is S.true:
1536
+ degenerate_step = None
1537
+ elif b.is_zero:
1538
+ degenerate_step = integral_steps(f*sqrt(a)**n, x)
1539
+ else:
1540
+ degenerate_step = sqrt_linear_rule(IntegralInfo(f*sqrt(a+b*x)**n, x))
1541
+
1542
+ def sqrt_quadratic_denom_rule(numer_poly: Poly, integrand: Expr):
1543
+ denom = sqrt(a+b*x+c*x**2)
1544
+ deg = numer_poly.degree()
1545
+ if deg <= 1:
1546
+ # integrand == (d+e*x)/sqrt(a+b*x+c*x**2)
1547
+ e, d = numer_poly.all_coeffs() if deg == 1 else (S.Zero, numer_poly.as_expr())
1548
+ # rewrite numerator to A*(2*c*x+b) + B
1549
+ A = e/(2*c)
1550
+ B = d-A*b
1551
+ pre_substitute = (2*c*x+b)/denom
1552
+ constant_step: Rule | None = None
1553
+ linear_step: Rule | None = None
1554
+ if A != 0:
1555
+ u = Dummy("u")
1556
+ pow_rule = PowerRule(1/sqrt(u), u, u, -S.Half)
1557
+ linear_step = URule(pre_substitute, x, u, a+b*x+c*x**2, pow_rule)
1558
+ if A != 1:
1559
+ linear_step = ConstantTimesRule(A*pre_substitute, x, A, pre_substitute, linear_step)
1560
+ if B != 0:
1561
+ constant_step = inverse_trig_rule(IntegralInfo(1/denom, x), degenerate=False)
1562
+ if B != 1:
1563
+ constant_step = ConstantTimesRule(B/denom, x, B, 1/denom, constant_step) # type: ignore
1564
+ if linear_step and constant_step:
1565
+ add = Add(A*pre_substitute, B/denom, evaluate=False)
1566
+ step: Rule | None = RewriteRule(integrand, x, add, AddRule(add, x, [linear_step, constant_step]))
1567
+ else:
1568
+ step = linear_step or constant_step
1569
+ else:
1570
+ coeffs = numer_poly.all_coeffs()
1571
+ step = SqrtQuadraticDenomRule(integrand, x, a, b, c, coeffs)
1572
+ return step
1573
+
1574
+ if n > 0: # rewrite poly * sqrt(s)**(2*k-1) to poly*s**k / sqrt(s)
1575
+ numer_poly = f_poly * (a+b*x+c*x**2)**((n+1)/2)
1576
+ rewritten = numer_poly.as_expr()/sqrt(a+b*x+c*x**2)
1577
+ substep = sqrt_quadratic_denom_rule(numer_poly, rewritten)
1578
+ generic_step = RewriteRule(integrand, x, rewritten, substep)
1579
+ elif n == -1:
1580
+ generic_step = sqrt_quadratic_denom_rule(f_poly, integrand)
1581
+ else:
1582
+ return # todo: handle n < -1 case
1583
+ return _add_degenerate_step(generic_cond, generic_step, degenerate_step)
1584
+
1585
+
1586
+ def hyperbolic_rule(integral: tuple[Expr, Symbol]):
1587
+ integrand, symbol = integral
1588
+ if isinstance(integrand, HyperbolicFunction) and integrand.args[0] == symbol:
1589
+ if integrand.func == sinh:
1590
+ return SinhRule(integrand, symbol)
1591
+ if integrand.func == cosh:
1592
+ return CoshRule(integrand, symbol)
1593
+ u = Dummy('u')
1594
+ if integrand.func == tanh:
1595
+ rewritten = sinh(symbol)/cosh(symbol)
1596
+ return RewriteRule(integrand, symbol, rewritten,
1597
+ URule(rewritten, symbol, u, cosh(symbol), ReciprocalRule(1/u, u, u)))
1598
+ if integrand.func == coth:
1599
+ rewritten = cosh(symbol)/sinh(symbol)
1600
+ return RewriteRule(integrand, symbol, rewritten,
1601
+ URule(rewritten, symbol, u, sinh(symbol), ReciprocalRule(1/u, u, u)))
1602
+ else:
1603
+ rewritten = integrand.rewrite(tanh)
1604
+ if integrand.func == sech:
1605
+ return RewriteRule(integrand, symbol, rewritten,
1606
+ URule(rewritten, symbol, u, tanh(symbol/2),
1607
+ ArctanRule(2/(u**2 + 1), u, S(2), S.One, S.One)))
1608
+ if integrand.func == csch:
1609
+ return RewriteRule(integrand, symbol, rewritten,
1610
+ URule(rewritten, symbol, u, tanh(symbol/2),
1611
+ ReciprocalRule(1/u, u, u)))
1612
+
1613
+ @cacheit
1614
+ def make_wilds(symbol):
1615
+ a = Wild('a', exclude=[symbol])
1616
+ b = Wild('b', exclude=[symbol])
1617
+ m = Wild('m', exclude=[symbol], properties=[lambda n: isinstance(n, Integer)])
1618
+ n = Wild('n', exclude=[symbol], properties=[lambda n: isinstance(n, Integer)])
1619
+
1620
+ return a, b, m, n
1621
+
1622
+ @cacheit
1623
+ def sincos_pattern(symbol):
1624
+ a, b, m, n = make_wilds(symbol)
1625
+ pattern = sin(a*symbol)**m * cos(b*symbol)**n
1626
+
1627
+ return pattern, a, b, m, n
1628
+
1629
+ @cacheit
1630
+ def tansec_pattern(symbol):
1631
+ a, b, m, n = make_wilds(symbol)
1632
+ pattern = tan(a*symbol)**m * sec(b*symbol)**n
1633
+
1634
+ return pattern, a, b, m, n
1635
+
1636
+ @cacheit
1637
+ def cotcsc_pattern(symbol):
1638
+ a, b, m, n = make_wilds(symbol)
1639
+ pattern = cot(a*symbol)**m * csc(b*symbol)**n
1640
+
1641
+ return pattern, a, b, m, n
1642
+
1643
+ @cacheit
1644
+ def heaviside_pattern(symbol):
1645
+ m = Wild('m', exclude=[symbol])
1646
+ b = Wild('b', exclude=[symbol])
1647
+ g = Wild('g')
1648
+ pattern = Heaviside(m*symbol + b) * g
1649
+
1650
+ return pattern, m, b, g
1651
+
1652
+ def uncurry(func):
1653
+ def uncurry_rl(args):
1654
+ return func(*args)
1655
+ return uncurry_rl
1656
+
1657
+ def trig_rewriter(rewrite):
1658
+ def trig_rewriter_rl(args):
1659
+ a, b, m, n, integrand, symbol = args
1660
+ rewritten = rewrite(a, b, m, n, integrand, symbol)
1661
+ if rewritten != integrand:
1662
+ return RewriteRule(integrand, symbol, rewritten, integral_steps(rewritten, symbol))
1663
+ return trig_rewriter_rl
1664
+
1665
+ sincos_botheven_condition = uncurry(
1666
+ lambda a, b, m, n, i, s: m.is_even and n.is_even and
1667
+ m.is_nonnegative and n.is_nonnegative)
1668
+
1669
+ sincos_botheven = trig_rewriter(
1670
+ lambda a, b, m, n, i, symbol: ( (((1 - cos(2*a*symbol)) / 2) ** (m / 2)) *
1671
+ (((1 + cos(2*b*symbol)) / 2) ** (n / 2)) ))
1672
+
1673
+ sincos_sinodd_condition = uncurry(lambda a, b, m, n, i, s: m.is_odd and m >= 3)
1674
+
1675
+ sincos_sinodd = trig_rewriter(
1676
+ lambda a, b, m, n, i, symbol: ( (1 - cos(a*symbol)**2)**((m - 1) / 2) *
1677
+ sin(a*symbol) *
1678
+ cos(b*symbol) ** n))
1679
+
1680
+ sincos_cosodd_condition = uncurry(lambda a, b, m, n, i, s: n.is_odd and n >= 3)
1681
+
1682
+ sincos_cosodd = trig_rewriter(
1683
+ lambda a, b, m, n, i, symbol: ( (1 - sin(b*symbol)**2)**((n - 1) / 2) *
1684
+ cos(b*symbol) *
1685
+ sin(a*symbol) ** m))
1686
+
1687
+ tansec_seceven_condition = uncurry(lambda a, b, m, n, i, s: n.is_even and n >= 4)
1688
+ tansec_seceven = trig_rewriter(
1689
+ lambda a, b, m, n, i, symbol: ( (1 + tan(b*symbol)**2) ** (n/2 - 1) *
1690
+ sec(b*symbol)**2 *
1691
+ tan(a*symbol) ** m ))
1692
+
1693
+ tansec_tanodd_condition = uncurry(lambda a, b, m, n, i, s: m.is_odd)
1694
+ tansec_tanodd = trig_rewriter(
1695
+ lambda a, b, m, n, i, symbol: ( (sec(a*symbol)**2 - 1) ** ((m - 1) / 2) *
1696
+ tan(a*symbol) *
1697
+ sec(b*symbol) ** n ))
1698
+
1699
+ tan_tansquared_condition = uncurry(lambda a, b, m, n, i, s: m == 2 and n == 0)
1700
+ tan_tansquared = trig_rewriter(
1701
+ lambda a, b, m, n, i, symbol: ( sec(a*symbol)**2 - 1))
1702
+
1703
+ cotcsc_csceven_condition = uncurry(lambda a, b, m, n, i, s: n.is_even and n >= 4)
1704
+ cotcsc_csceven = trig_rewriter(
1705
+ lambda a, b, m, n, i, symbol: ( (1 + cot(b*symbol)**2) ** (n/2 - 1) *
1706
+ csc(b*symbol)**2 *
1707
+ cot(a*symbol) ** m ))
1708
+
1709
+ cotcsc_cotodd_condition = uncurry(lambda a, b, m, n, i, s: m.is_odd)
1710
+ cotcsc_cotodd = trig_rewriter(
1711
+ lambda a, b, m, n, i, symbol: ( (csc(a*symbol)**2 - 1) ** ((m - 1) / 2) *
1712
+ cot(a*symbol) *
1713
+ csc(b*symbol) ** n ))
1714
+
1715
+ def trig_sincos_rule(integral):
1716
+ integrand, symbol = integral
1717
+
1718
+ if any(integrand.has(f) for f in (sin, cos)):
1719
+ pattern, a, b, m, n = sincos_pattern(symbol)
1720
+ match = integrand.match(pattern)
1721
+ if not match:
1722
+ return
1723
+
1724
+ return multiplexer({
1725
+ sincos_botheven_condition: sincos_botheven,
1726
+ sincos_sinodd_condition: sincos_sinodd,
1727
+ sincos_cosodd_condition: sincos_cosodd
1728
+ })(tuple(
1729
+ [match.get(i, S.Zero) for i in (a, b, m, n)] +
1730
+ [integrand, symbol]))
1731
+
1732
+ def trig_tansec_rule(integral):
1733
+ integrand, symbol = integral
1734
+
1735
+ integrand = integrand.subs({
1736
+ 1 / cos(symbol): sec(symbol)
1737
+ })
1738
+
1739
+ if any(integrand.has(f) for f in (tan, sec)):
1740
+ pattern, a, b, m, n = tansec_pattern(symbol)
1741
+ match = integrand.match(pattern)
1742
+ if not match:
1743
+ return
1744
+
1745
+ return multiplexer({
1746
+ tansec_tanodd_condition: tansec_tanodd,
1747
+ tansec_seceven_condition: tansec_seceven,
1748
+ tan_tansquared_condition: tan_tansquared
1749
+ })(tuple(
1750
+ [match.get(i, S.Zero) for i in (a, b, m, n)] +
1751
+ [integrand, symbol]))
1752
+
1753
+ def trig_cotcsc_rule(integral):
1754
+ integrand, symbol = integral
1755
+ integrand = integrand.subs({
1756
+ 1 / sin(symbol): csc(symbol),
1757
+ 1 / tan(symbol): cot(symbol),
1758
+ cos(symbol) / tan(symbol): cot(symbol)
1759
+ })
1760
+
1761
+ if any(integrand.has(f) for f in (cot, csc)):
1762
+ pattern, a, b, m, n = cotcsc_pattern(symbol)
1763
+ match = integrand.match(pattern)
1764
+ if not match:
1765
+ return
1766
+
1767
+ return multiplexer({
1768
+ cotcsc_cotodd_condition: cotcsc_cotodd,
1769
+ cotcsc_csceven_condition: cotcsc_csceven
1770
+ })(tuple(
1771
+ [match.get(i, S.Zero) for i in (a, b, m, n)] +
1772
+ [integrand, symbol]))
1773
+
1774
+ def trig_sindouble_rule(integral):
1775
+ integrand, symbol = integral
1776
+ a = Wild('a', exclude=[sin(2*symbol)])
1777
+ match = integrand.match(sin(2*symbol)*a)
1778
+ if match:
1779
+ sin_double = 2*sin(symbol)*cos(symbol)/sin(2*symbol)
1780
+ return integral_steps(integrand * sin_double, symbol)
1781
+
1782
+ def trig_powers_products_rule(integral):
1783
+ return do_one(null_safe(trig_sincos_rule),
1784
+ null_safe(trig_tansec_rule),
1785
+ null_safe(trig_cotcsc_rule),
1786
+ null_safe(trig_sindouble_rule))(integral)
1787
+
1788
+ def trig_substitution_rule(integral):
1789
+ integrand, symbol = integral
1790
+ A = Wild('a', exclude=[0, symbol])
1791
+ B = Wild('b', exclude=[0, symbol])
1792
+ theta = Dummy("theta")
1793
+ target_pattern = A + B*symbol**2
1794
+
1795
+ matches = integrand.find(target_pattern)
1796
+ for expr in matches:
1797
+ match = expr.match(target_pattern)
1798
+ a = match.get(A, S.Zero)
1799
+ b = match.get(B, S.Zero)
1800
+
1801
+ a_positive = ((a.is_number and a > 0) or a.is_positive)
1802
+ b_positive = ((b.is_number and b > 0) or b.is_positive)
1803
+ a_negative = ((a.is_number and a < 0) or a.is_negative)
1804
+ b_negative = ((b.is_number and b < 0) or b.is_negative)
1805
+ x_func = None
1806
+ if a_positive and b_positive:
1807
+ # a**2 + b*x**2. Assume sec(theta) > 0, -pi/2 < theta < pi/2
1808
+ x_func = (sqrt(a)/sqrt(b)) * tan(theta)
1809
+ # Do not restrict the domain: tan(theta) takes on any real
1810
+ # value on the interval -pi/2 < theta < pi/2 so x takes on
1811
+ # any value
1812
+ restriction = True
1813
+ elif a_positive and b_negative:
1814
+ # a**2 - b*x**2. Assume cos(theta) > 0, -pi/2 < theta < pi/2
1815
+ constant = sqrt(a)/sqrt(-b)
1816
+ x_func = constant * sin(theta)
1817
+ restriction = And(symbol > -constant, symbol < constant)
1818
+ elif a_negative and b_positive:
1819
+ # b*x**2 - a**2. Assume sin(theta) > 0, 0 < theta < pi
1820
+ constant = sqrt(-a)/sqrt(b)
1821
+ x_func = constant * sec(theta)
1822
+ restriction = And(symbol > -constant, symbol < constant)
1823
+ if x_func:
1824
+ # Manually simplify sqrt(trig(theta)**2) to trig(theta)
1825
+ # Valid due to assumed domain restriction
1826
+ substitutions = {}
1827
+ for f in [sin, cos, tan,
1828
+ sec, csc, cot]:
1829
+ substitutions[sqrt(f(theta)**2)] = f(theta)
1830
+ substitutions[sqrt(f(theta)**(-2))] = 1/f(theta)
1831
+
1832
+ replaced = integrand.subs(symbol, x_func).trigsimp()
1833
+ replaced = manual_subs(replaced, substitutions)
1834
+ if not replaced.has(symbol):
1835
+ replaced *= manual_diff(x_func, theta)
1836
+ replaced = replaced.trigsimp()
1837
+ secants = replaced.find(1/cos(theta))
1838
+ if secants:
1839
+ replaced = replaced.xreplace({
1840
+ 1/cos(theta): sec(theta)
1841
+ })
1842
+
1843
+ substep = integral_steps(replaced, theta)
1844
+ if not substep.contains_dont_know():
1845
+ return TrigSubstitutionRule(integrand, symbol,
1846
+ theta, x_func, replaced, substep, restriction)
1847
+
1848
+ def heaviside_rule(integral):
1849
+ integrand, symbol = integral
1850
+ pattern, m, b, g = heaviside_pattern(symbol)
1851
+ match = integrand.match(pattern)
1852
+ if match and 0 != match[g]:
1853
+ # f = Heaviside(m*x + b)*g
1854
+ substep = integral_steps(match[g], symbol)
1855
+ m, b = match[m], match[b]
1856
+ return HeavisideRule(integrand, symbol, m*symbol + b, -b/m, substep)
1857
+
1858
+
1859
+ def dirac_delta_rule(integral: IntegralInfo):
1860
+ integrand, x = integral
1861
+ if len(integrand.args) == 1:
1862
+ n = S.Zero
1863
+ else:
1864
+ n = integrand.args[1]
1865
+ if not n.is_Integer or n < 0:
1866
+ return
1867
+ a, b = Wild('a', exclude=[x]), Wild('b', exclude=[x, 0])
1868
+ match = integrand.args[0].match(a+b*x)
1869
+ if not match:
1870
+ return
1871
+ a, b = match[a], match[b]
1872
+ generic_cond = Ne(b, 0)
1873
+ if generic_cond is S.true:
1874
+ degenerate_step = None
1875
+ else:
1876
+ degenerate_step = ConstantRule(DiracDelta(a, n), x)
1877
+ generic_step = DiracDeltaRule(integrand, x, n, a, b)
1878
+ return _add_degenerate_step(generic_cond, generic_step, degenerate_step)
1879
+
1880
+
1881
+ def substitution_rule(integral):
1882
+ integrand, symbol = integral
1883
+
1884
+ u_var = Dummy("u")
1885
+ substitutions = find_substitutions(integrand, symbol, u_var)
1886
+ count = 0
1887
+ if substitutions:
1888
+ debug("List of Substitution Rules")
1889
+ ways = []
1890
+ for u_func, c, substituted in substitutions:
1891
+ subrule = integral_steps(substituted, u_var)
1892
+ count = count + 1
1893
+ debug("Rule {}: {}".format(count, subrule))
1894
+
1895
+ if subrule.contains_dont_know():
1896
+ continue
1897
+
1898
+ if simplify(c - 1) != 0:
1899
+ _, denom = c.as_numer_denom()
1900
+ if subrule:
1901
+ subrule = ConstantTimesRule(c * substituted, u_var, c, substituted, subrule)
1902
+
1903
+ if denom.free_symbols:
1904
+ piecewise = []
1905
+ could_be_zero = []
1906
+
1907
+ if isinstance(denom, Mul):
1908
+ could_be_zero = denom.args
1909
+ else:
1910
+ could_be_zero.append(denom)
1911
+
1912
+ for expr in could_be_zero:
1913
+ if not fuzzy_not(expr.is_zero):
1914
+ substep = integral_steps(manual_subs(integrand, expr, 0), symbol)
1915
+
1916
+ if substep:
1917
+ piecewise.append((
1918
+ substep,
1919
+ Eq(expr, 0)
1920
+ ))
1921
+ piecewise.append((subrule, True))
1922
+ subrule = PiecewiseRule(substituted, symbol, piecewise)
1923
+
1924
+ ways.append(URule(integrand, symbol, u_var, u_func, subrule))
1925
+
1926
+ if len(ways) > 1:
1927
+ return AlternativeRule(integrand, symbol, ways)
1928
+ elif ways:
1929
+ return ways[0]
1930
+
1931
+
1932
+ partial_fractions_rule = rewriter(
1933
+ lambda integrand, symbol: integrand.is_rational_function(),
1934
+ lambda integrand, symbol: integrand.apart(symbol))
1935
+
1936
+ cancel_rule = rewriter(
1937
+ # lambda integrand, symbol: integrand.is_algebraic_expr(),
1938
+ # lambda integrand, symbol: isinstance(integrand, Mul),
1939
+ lambda integrand, symbol: True,
1940
+ lambda integrand, symbol: integrand.cancel())
1941
+
1942
+ distribute_expand_rule = rewriter(
1943
+ lambda integrand, symbol: (
1944
+ all(arg.is_Pow or arg.is_polynomial(symbol) for arg in integrand.args)
1945
+ or isinstance(integrand, Pow)
1946
+ or isinstance(integrand, Mul)),
1947
+ lambda integrand, symbol: integrand.expand())
1948
+
1949
+ trig_expand_rule = rewriter(
1950
+ # If there are trig functions with different arguments, expand them
1951
+ lambda integrand, symbol: (
1952
+ len({a.args[0] for a in integrand.atoms(TrigonometricFunction)}) > 1),
1953
+ lambda integrand, symbol: integrand.expand(trig=True))
1954
+
1955
+ def derivative_rule(integral):
1956
+ integrand = integral[0]
1957
+ diff_variables = integrand.variables
1958
+ undifferentiated_function = integrand.expr
1959
+ integrand_variables = undifferentiated_function.free_symbols
1960
+
1961
+ if integral.symbol in integrand_variables:
1962
+ if integral.symbol in diff_variables:
1963
+ return DerivativeRule(*integral)
1964
+ else:
1965
+ return DontKnowRule(integrand, integral.symbol)
1966
+ else:
1967
+ return ConstantRule(*integral)
1968
+
1969
+ def rewrites_rule(integral):
1970
+ integrand, symbol = integral
1971
+
1972
+ if integrand.match(1/cos(symbol)):
1973
+ rewritten = integrand.subs(1/cos(symbol), sec(symbol))
1974
+ return RewriteRule(integrand, symbol, rewritten, integral_steps(rewritten, symbol))
1975
+
1976
+ def fallback_rule(integral):
1977
+ return DontKnowRule(*integral)
1978
+
1979
+ # Cache is used to break cyclic integrals.
1980
+ # Need to use the same dummy variable in cached expressions for them to match.
1981
+ # Also record "u" of integration by parts, to avoid infinite repetition.
1982
+ _integral_cache: dict[Expr, Expr | None] = {}
1983
+ _parts_u_cache: dict[Expr, int] = defaultdict(int)
1984
+ _cache_dummy = Dummy("z")
1985
+
1986
+ def integral_steps(integrand, symbol, **options):
1987
+ """Returns the steps needed to compute an integral.
1988
+
1989
+ Explanation
1990
+ ===========
1991
+
1992
+ This function attempts to mirror what a student would do by hand as
1993
+ closely as possible.
1994
+
1995
+ SymPy Gamma uses this to provide a step-by-step explanation of an
1996
+ integral. The code it uses to format the results of this function can be
1997
+ found at
1998
+ https://github.com/sympy/sympy_gamma/blob/master/app/logic/intsteps.py.
1999
+
2000
+ Examples
2001
+ ========
2002
+
2003
+ >>> from sympy import exp, sin
2004
+ >>> from sympy.integrals.manualintegrate import integral_steps
2005
+ >>> from sympy.abc import x
2006
+ >>> print(repr(integral_steps(exp(x) / (1 + exp(2 * x)), x))) \
2007
+ # doctest: +NORMALIZE_WHITESPACE
2008
+ URule(integrand=exp(x)/(exp(2*x) + 1), variable=x, u_var=_u, u_func=exp(x),
2009
+ substep=ArctanRule(integrand=1/(_u**2 + 1), variable=_u, a=1, b=1, c=1))
2010
+ >>> print(repr(integral_steps(sin(x), x))) \
2011
+ # doctest: +NORMALIZE_WHITESPACE
2012
+ SinRule(integrand=sin(x), variable=x)
2013
+ >>> print(repr(integral_steps((x**2 + 3)**2, x))) \
2014
+ # doctest: +NORMALIZE_WHITESPACE
2015
+ RewriteRule(integrand=(x**2 + 3)**2, variable=x, rewritten=x**4 + 6*x**2 + 9,
2016
+ substep=AddRule(integrand=x**4 + 6*x**2 + 9, variable=x,
2017
+ substeps=[PowerRule(integrand=x**4, variable=x, base=x, exp=4),
2018
+ ConstantTimesRule(integrand=6*x**2, variable=x, constant=6, other=x**2,
2019
+ substep=PowerRule(integrand=x**2, variable=x, base=x, exp=2)),
2020
+ ConstantRule(integrand=9, variable=x)]))
2021
+
2022
+ Returns
2023
+ =======
2024
+
2025
+ rule : Rule
2026
+ The first step; most rules have substeps that must also be
2027
+ considered. These substeps can be evaluated using ``manualintegrate``
2028
+ to obtain a result.
2029
+
2030
+ """
2031
+ cachekey = integrand.xreplace({symbol: _cache_dummy})
2032
+ if cachekey in _integral_cache:
2033
+ if _integral_cache[cachekey] is None:
2034
+ # Stop this attempt, because it leads around in a loop
2035
+ return DontKnowRule(integrand, symbol)
2036
+ else:
2037
+ # TODO: This is for future development, as currently
2038
+ # _integral_cache gets no values other than None
2039
+ return (_integral_cache[cachekey].xreplace(_cache_dummy, symbol),
2040
+ symbol)
2041
+ else:
2042
+ _integral_cache[cachekey] = None
2043
+
2044
+ integral = IntegralInfo(integrand, symbol)
2045
+
2046
+ def key(integral):
2047
+ integrand = integral.integrand
2048
+
2049
+ if symbol not in integrand.free_symbols:
2050
+ return Number
2051
+ for cls in (Symbol, TrigonometricFunction, OrthogonalPolynomial):
2052
+ if isinstance(integrand, cls):
2053
+ return cls
2054
+ return type(integrand)
2055
+
2056
+ def integral_is_subclass(*klasses):
2057
+ def _integral_is_subclass(integral):
2058
+ k = key(integral)
2059
+ return k and issubclass(k, klasses)
2060
+ return _integral_is_subclass
2061
+
2062
+ result = do_one(
2063
+ null_safe(special_function_rule),
2064
+ null_safe(switch(key, {
2065
+ Pow: do_one(null_safe(power_rule), null_safe(inverse_trig_rule),
2066
+ null_safe(sqrt_linear_rule),
2067
+ null_safe(quadratic_denom_rule)),
2068
+ Symbol: power_rule,
2069
+ exp: exp_rule,
2070
+ Add: add_rule,
2071
+ Mul: do_one(null_safe(mul_rule), null_safe(trig_product_rule),
2072
+ null_safe(heaviside_rule), null_safe(quadratic_denom_rule),
2073
+ null_safe(sqrt_linear_rule),
2074
+ null_safe(sqrt_quadratic_rule)),
2075
+ Derivative: derivative_rule,
2076
+ TrigonometricFunction: trig_rule,
2077
+ Heaviside: heaviside_rule,
2078
+ DiracDelta: dirac_delta_rule,
2079
+ OrthogonalPolynomial: orthogonal_poly_rule,
2080
+ Number: constant_rule
2081
+ })),
2082
+ do_one(
2083
+ null_safe(trig_rule),
2084
+ null_safe(hyperbolic_rule),
2085
+ null_safe(alternatives(
2086
+ rewrites_rule,
2087
+ substitution_rule,
2088
+ condition(
2089
+ integral_is_subclass(Mul, Pow),
2090
+ partial_fractions_rule),
2091
+ condition(
2092
+ integral_is_subclass(Mul, Pow),
2093
+ cancel_rule),
2094
+ condition(
2095
+ integral_is_subclass(Mul, log,
2096
+ *inverse_trig_functions),
2097
+ parts_rule),
2098
+ condition(
2099
+ integral_is_subclass(Mul, Pow),
2100
+ distribute_expand_rule),
2101
+ trig_powers_products_rule,
2102
+ trig_expand_rule
2103
+ )),
2104
+ null_safe(condition(integral_is_subclass(Mul, Pow), nested_pow_rule)),
2105
+ null_safe(trig_substitution_rule)
2106
+ ),
2107
+ fallback_rule)(integral)
2108
+ del _integral_cache[cachekey]
2109
+ return result
2110
+
2111
+
2112
+ def manualintegrate(f, var):
2113
+ """manualintegrate(f, var)
2114
+
2115
+ Explanation
2116
+ ===========
2117
+
2118
+ Compute indefinite integral of a single variable using an algorithm that
2119
+ resembles what a student would do by hand.
2120
+
2121
+ Unlike :func:`~.integrate`, var can only be a single symbol.
2122
+
2123
+ Examples
2124
+ ========
2125
+
2126
+ >>> from sympy import sin, cos, tan, exp, log, integrate
2127
+ >>> from sympy.integrals.manualintegrate import manualintegrate
2128
+ >>> from sympy.abc import x
2129
+ >>> manualintegrate(1 / x, x)
2130
+ log(x)
2131
+ >>> integrate(1/x)
2132
+ log(x)
2133
+ >>> manualintegrate(log(x), x)
2134
+ x*log(x) - x
2135
+ >>> integrate(log(x))
2136
+ x*log(x) - x
2137
+ >>> manualintegrate(exp(x) / (1 + exp(2 * x)), x)
2138
+ atan(exp(x))
2139
+ >>> integrate(exp(x) / (1 + exp(2 * x)))
2140
+ RootSum(4*_z**2 + 1, Lambda(_i, _i*log(2*_i + exp(x))))
2141
+ >>> manualintegrate(cos(x)**4 * sin(x), x)
2142
+ -cos(x)**5/5
2143
+ >>> integrate(cos(x)**4 * sin(x), x)
2144
+ -cos(x)**5/5
2145
+ >>> manualintegrate(cos(x)**4 * sin(x)**3, x)
2146
+ cos(x)**7/7 - cos(x)**5/5
2147
+ >>> integrate(cos(x)**4 * sin(x)**3, x)
2148
+ cos(x)**7/7 - cos(x)**5/5
2149
+ >>> manualintegrate(tan(x), x)
2150
+ -log(cos(x))
2151
+ >>> integrate(tan(x), x)
2152
+ -log(cos(x))
2153
+
2154
+ See Also
2155
+ ========
2156
+
2157
+ sympy.integrals.integrals.integrate
2158
+ sympy.integrals.integrals.Integral.doit
2159
+ sympy.integrals.integrals.Integral
2160
+ """
2161
+ result = integral_steps(f, var).eval()
2162
+ # Clear the cache of u-parts
2163
+ _parts_u_cache.clear()
2164
+ # If we got Piecewise with two parts, put generic first
2165
+ if isinstance(result, Piecewise) and len(result.args) == 2:
2166
+ cond = result.args[0][1]
2167
+ if isinstance(cond, Eq) and result.args[1][1] == True:
2168
+ result = result.func(
2169
+ (result.args[1][0], Ne(*cond.args)),
2170
+ (result.args[0][0], True))
2171
+ return result
venv/lib/python3.10/site-packages/sympy/integrals/meijerint.py ADDED
@@ -0,0 +1,2190 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """
2
+ Integrate functions by rewriting them as Meijer G-functions.
3
+
4
+ There are three user-visible functions that can be used by other parts of the
5
+ sympy library to solve various integration problems:
6
+
7
+ - meijerint_indefinite
8
+ - meijerint_definite
9
+ - meijerint_inversion
10
+
11
+ They can be used to compute, respectively, indefinite integrals, definite
12
+ integrals over intervals of the real line, and inverse laplace-type integrals
13
+ (from c-I*oo to c+I*oo). See the respective docstrings for details.
14
+
15
+ The main references for this are:
16
+
17
+ [L] Luke, Y. L. (1969), The Special Functions and Their Approximations,
18
+ Volume 1
19
+
20
+ [R] Kelly B. Roach. Meijer G Function Representations.
21
+ In: Proceedings of the 1997 International Symposium on Symbolic and
22
+ Algebraic Computation, pages 205-211, New York, 1997. ACM.
23
+
24
+ [P] A. P. Prudnikov, Yu. A. Brychkov and O. I. Marichev (1990).
25
+ Integrals and Series: More Special Functions, Vol. 3,.
26
+ Gordon and Breach Science Publisher
27
+ """
28
+
29
+ from __future__ import annotations
30
+ import itertools
31
+
32
+ from sympy import SYMPY_DEBUG
33
+ from sympy.core import S, Expr
34
+ from sympy.core.add import Add
35
+ from sympy.core.basic import Basic
36
+ from sympy.core.cache import cacheit
37
+ from sympy.core.containers import Tuple
38
+ from sympy.core.exprtools import factor_terms
39
+ from sympy.core.function import (expand, expand_mul, expand_power_base,
40
+ expand_trig, Function)
41
+ from sympy.core.mul import Mul
42
+ from sympy.core.numbers import ilcm, Rational, pi
43
+ from sympy.core.relational import Eq, Ne, _canonical_coeff
44
+ from sympy.core.sorting import default_sort_key, ordered
45
+ from sympy.core.symbol import Dummy, symbols, Wild, Symbol
46
+ from sympy.core.sympify import sympify
47
+ from sympy.functions.combinatorial.factorials import factorial
48
+ from sympy.functions.elementary.complexes import (re, im, arg, Abs, sign,
49
+ unpolarify, polarify, polar_lift, principal_branch, unbranched_argument,
50
+ periodic_argument)
51
+ from sympy.functions.elementary.exponential import exp, exp_polar, log
52
+ from sympy.functions.elementary.integers import ceiling
53
+ from sympy.functions.elementary.hyperbolic import (cosh, sinh,
54
+ _rewrite_hyperbolics_as_exp, HyperbolicFunction)
55
+ from sympy.functions.elementary.miscellaneous import sqrt
56
+ from sympy.functions.elementary.piecewise import Piecewise, piecewise_fold
57
+ from sympy.functions.elementary.trigonometric import (cos, sin, sinc,
58
+ TrigonometricFunction)
59
+ from sympy.functions.special.bessel import besselj, bessely, besseli, besselk
60
+ from sympy.functions.special.delta_functions import DiracDelta, Heaviside
61
+ from sympy.functions.special.elliptic_integrals import elliptic_k, elliptic_e
62
+ from sympy.functions.special.error_functions import (erf, erfc, erfi, Ei,
63
+ expint, Si, Ci, Shi, Chi, fresnels, fresnelc)
64
+ from sympy.functions.special.gamma_functions import gamma
65
+ from sympy.functions.special.hyper import hyper, meijerg
66
+ from sympy.functions.special.singularity_functions import SingularityFunction
67
+ from .integrals import Integral
68
+ from sympy.logic.boolalg import And, Or, BooleanAtom, Not, BooleanFunction
69
+ from sympy.polys import cancel, factor
70
+ from sympy.utilities.iterables import multiset_partitions
71
+ from sympy.utilities.misc import debug as _debug
72
+ from sympy.utilities.misc import debugf as _debugf
73
+
74
+ # keep this at top for easy reference
75
+ z = Dummy('z')
76
+
77
+
78
+ def _has(res, *f):
79
+ # return True if res has f; in the case of Piecewise
80
+ # only return True if *all* pieces have f
81
+ res = piecewise_fold(res)
82
+ if getattr(res, 'is_Piecewise', False):
83
+ return all(_has(i, *f) for i in res.args)
84
+ return res.has(*f)
85
+
86
+
87
+ def _create_lookup_table(table):
88
+ """ Add formulae for the function -> meijerg lookup table. """
89
+ def wild(n):
90
+ return Wild(n, exclude=[z])
91
+ p, q, a, b, c = list(map(wild, 'pqabc'))
92
+ n = Wild('n', properties=[lambda x: x.is_Integer and x > 0])
93
+ t = p*z**q
94
+
95
+ def add(formula, an, ap, bm, bq, arg=t, fac=S.One, cond=True, hint=True):
96
+ table.setdefault(_mytype(formula, z), []).append((formula,
97
+ [(fac, meijerg(an, ap, bm, bq, arg))], cond, hint))
98
+
99
+ def addi(formula, inst, cond, hint=True):
100
+ table.setdefault(
101
+ _mytype(formula, z), []).append((formula, inst, cond, hint))
102
+
103
+ def constant(a):
104
+ return [(a, meijerg([1], [], [], [0], z)),
105
+ (a, meijerg([], [1], [0], [], z))]
106
+ table[()] = [(a, constant(a), True, True)]
107
+
108
+ # [P], Section 8.
109
+ class IsNonPositiveInteger(Function):
110
+
111
+ @classmethod
112
+ def eval(cls, arg):
113
+ arg = unpolarify(arg)
114
+ if arg.is_Integer is True:
115
+ return arg <= 0
116
+
117
+ # Section 8.4.2
118
+ # TODO this needs more polar_lift (c/f entry for exp)
119
+ add(Heaviside(t - b)*(t - b)**(a - 1), [a], [], [], [0], t/b,
120
+ gamma(a)*b**(a - 1), And(b > 0))
121
+ add(Heaviside(b - t)*(b - t)**(a - 1), [], [a], [0], [], t/b,
122
+ gamma(a)*b**(a - 1), And(b > 0))
123
+ add(Heaviside(z - (b/p)**(1/q))*(t - b)**(a - 1), [a], [], [], [0], t/b,
124
+ gamma(a)*b**(a - 1), And(b > 0))
125
+ add(Heaviside((b/p)**(1/q) - z)*(b - t)**(a - 1), [], [a], [0], [], t/b,
126
+ gamma(a)*b**(a - 1), And(b > 0))
127
+ add((b + t)**(-a), [1 - a], [], [0], [], t/b, b**(-a)/gamma(a),
128
+ hint=Not(IsNonPositiveInteger(a)))
129
+ add(Abs(b - t)**(-a), [1 - a], [(1 - a)/2], [0], [(1 - a)/2], t/b,
130
+ 2*sin(pi*a/2)*gamma(1 - a)*Abs(b)**(-a), re(a) < 1)
131
+ add((t**a - b**a)/(t - b), [0, a], [], [0, a], [], t/b,
132
+ b**(a - 1)*sin(a*pi)/pi)
133
+
134
+ # 12
135
+ def A1(r, sign, nu):
136
+ return pi**Rational(-1, 2)*(-sign*nu/2)**(1 - 2*r)
137
+
138
+ def tmpadd(r, sgn):
139
+ # XXX the a**2 is bad for matching
140
+ add((sqrt(a**2 + t) + sgn*a)**b/(a**2 + t)**r,
141
+ [(1 + b)/2, 1 - 2*r + b/2], [],
142
+ [(b - sgn*b)/2], [(b + sgn*b)/2], t/a**2,
143
+ a**(b - 2*r)*A1(r, sgn, b))
144
+ tmpadd(0, 1)
145
+ tmpadd(0, -1)
146
+ tmpadd(S.Half, 1)
147
+ tmpadd(S.Half, -1)
148
+
149
+ # 13
150
+ def tmpadd(r, sgn):
151
+ add((sqrt(a + p*z**q) + sgn*sqrt(p)*z**(q/2))**b/(a + p*z**q)**r,
152
+ [1 - r + sgn*b/2], [1 - r - sgn*b/2], [0, S.Half], [],
153
+ p*z**q/a, a**(b/2 - r)*A1(r, sgn, b))
154
+ tmpadd(0, 1)
155
+ tmpadd(0, -1)
156
+ tmpadd(S.Half, 1)
157
+ tmpadd(S.Half, -1)
158
+ # (those after look obscure)
159
+
160
+ # Section 8.4.3
161
+ add(exp(polar_lift(-1)*t), [], [], [0], [])
162
+
163
+ # TODO can do sin^n, sinh^n by expansion ... where?
164
+ # 8.4.4 (hyperbolic functions)
165
+ add(sinh(t), [], [1], [S.Half], [1, 0], t**2/4, pi**Rational(3, 2))
166
+ add(cosh(t), [], [S.Half], [0], [S.Half, S.Half], t**2/4, pi**Rational(3, 2))
167
+
168
+ # Section 8.4.5
169
+ # TODO can do t + a. but can also do by expansion... (XXX not really)
170
+ add(sin(t), [], [], [S.Half], [0], t**2/4, sqrt(pi))
171
+ add(cos(t), [], [], [0], [S.Half], t**2/4, sqrt(pi))
172
+
173
+ # Section 8.4.6 (sinc function)
174
+ add(sinc(t), [], [], [0], [Rational(-1, 2)], t**2/4, sqrt(pi)/2)
175
+
176
+ # Section 8.5.5
177
+ def make_log1(subs):
178
+ N = subs[n]
179
+ return [(S.NegativeOne**N*factorial(N),
180
+ meijerg([], [1]*(N + 1), [0]*(N + 1), [], t))]
181
+
182
+ def make_log2(subs):
183
+ N = subs[n]
184
+ return [(factorial(N),
185
+ meijerg([1]*(N + 1), [], [], [0]*(N + 1), t))]
186
+ # TODO these only hold for positive p, and can be made more general
187
+ # but who uses log(x)*Heaviside(a-x) anyway ...
188
+ # TODO also it would be nice to derive them recursively ...
189
+ addi(log(t)**n*Heaviside(1 - t), make_log1, True)
190
+ addi(log(t)**n*Heaviside(t - 1), make_log2, True)
191
+
192
+ def make_log3(subs):
193
+ return make_log1(subs) + make_log2(subs)
194
+ addi(log(t)**n, make_log3, True)
195
+ addi(log(t + a),
196
+ constant(log(a)) + [(S.One, meijerg([1, 1], [], [1], [0], t/a))],
197
+ True)
198
+ addi(log(Abs(t - a)), constant(log(Abs(a))) +
199
+ [(pi, meijerg([1, 1], [S.Half], [1], [0, S.Half], t/a))],
200
+ True)
201
+ # TODO log(x)/(x+a) and log(x)/(x-1) can also be done. should they
202
+ # be derivable?
203
+ # TODO further formulae in this section seem obscure
204
+
205
+ # Sections 8.4.9-10
206
+ # TODO
207
+
208
+ # Section 8.4.11
209
+ addi(Ei(t),
210
+ constant(-S.ImaginaryUnit*pi) + [(S.NegativeOne, meijerg([], [1], [0, 0], [],
211
+ t*polar_lift(-1)))],
212
+ True)
213
+
214
+ # Section 8.4.12
215
+ add(Si(t), [1], [], [S.Half], [0, 0], t**2/4, sqrt(pi)/2)
216
+ add(Ci(t), [], [1], [0, 0], [S.Half], t**2/4, -sqrt(pi)/2)
217
+
218
+ # Section 8.4.13
219
+ add(Shi(t), [S.Half], [], [0], [Rational(-1, 2), Rational(-1, 2)], polar_lift(-1)*t**2/4,
220
+ t*sqrt(pi)/4)
221
+ add(Chi(t), [], [S.Half, 1], [0, 0], [S.Half, S.Half], t**2/4, -
222
+ pi**S('3/2')/2)
223
+
224
+ # generalized exponential integral
225
+ add(expint(a, t), [], [a], [a - 1, 0], [], t)
226
+
227
+ # Section 8.4.14
228
+ add(erf(t), [1], [], [S.Half], [0], t**2, 1/sqrt(pi))
229
+ # TODO exp(-x)*erf(I*x) does not work
230
+ add(erfc(t), [], [1], [0, S.Half], [], t**2, 1/sqrt(pi))
231
+ # This formula for erfi(z) yields a wrong(?) minus sign
232
+ #add(erfi(t), [1], [], [S.Half], [0], -t**2, I/sqrt(pi))
233
+ add(erfi(t), [S.Half], [], [0], [Rational(-1, 2)], -t**2, t/sqrt(pi))
234
+
235
+ # Fresnel Integrals
236
+ add(fresnels(t), [1], [], [Rational(3, 4)], [0, Rational(1, 4)], pi**2*t**4/16, S.Half)
237
+ add(fresnelc(t), [1], [], [Rational(1, 4)], [0, Rational(3, 4)], pi**2*t**4/16, S.Half)
238
+
239
+ ##### bessel-type functions #####
240
+ # Section 8.4.19
241
+ add(besselj(a, t), [], [], [a/2], [-a/2], t**2/4)
242
+
243
+ # all of the following are derivable
244
+ #add(sin(t)*besselj(a, t), [Rational(1, 4), Rational(3, 4)], [], [(1+a)/2],
245
+ # [-a/2, a/2, (1-a)/2], t**2, 1/sqrt(2))
246
+ #add(cos(t)*besselj(a, t), [Rational(1, 4), Rational(3, 4)], [], [a/2],
247
+ # [-a/2, (1+a)/2, (1-a)/2], t**2, 1/sqrt(2))
248
+ #add(besselj(a, t)**2, [S.Half], [], [a], [-a, 0], t**2, 1/sqrt(pi))
249
+ #add(besselj(a, t)*besselj(b, t), [0, S.Half], [], [(a + b)/2],
250
+ # [-(a+b)/2, (a - b)/2, (b - a)/2], t**2, 1/sqrt(pi))
251
+
252
+ # Section 8.4.20
253
+ add(bessely(a, t), [], [-(a + 1)/2], [a/2, -a/2], [-(a + 1)/2], t**2/4)
254
+
255
+ # TODO all of the following should be derivable
256
+ #add(sin(t)*bessely(a, t), [Rational(1, 4), Rational(3, 4)], [(1 - a - 1)/2],
257
+ # [(1 + a)/2, (1 - a)/2], [(1 - a - 1)/2, (1 - 1 - a)/2, (1 - 1 + a)/2],
258
+ # t**2, 1/sqrt(2))
259
+ #add(cos(t)*bessely(a, t), [Rational(1, 4), Rational(3, 4)], [(0 - a - 1)/2],
260
+ # [(0 + a)/2, (0 - a)/2], [(0 - a - 1)/2, (1 - 0 - a)/2, (1 - 0 + a)/2],
261
+ # t**2, 1/sqrt(2))
262
+ #add(besselj(a, t)*bessely(b, t), [0, S.Half], [(a - b - 1)/2],
263
+ # [(a + b)/2, (a - b)/2], [(a - b - 1)/2, -(a + b)/2, (b - a)/2],
264
+ # t**2, 1/sqrt(pi))
265
+ #addi(bessely(a, t)**2,
266
+ # [(2/sqrt(pi), meijerg([], [S.Half, S.Half - a], [0, a, -a],
267
+ # [S.Half - a], t**2)),
268
+ # (1/sqrt(pi), meijerg([S.Half], [], [a], [-a, 0], t**2))],
269
+ # True)
270
+ #addi(bessely(a, t)*bessely(b, t),
271
+ # [(2/sqrt(pi), meijerg([], [0, S.Half, (1 - a - b)/2],
272
+ # [(a + b)/2, (a - b)/2, (b - a)/2, -(a + b)/2],
273
+ # [(1 - a - b)/2], t**2)),
274
+ # (1/sqrt(pi), meijerg([0, S.Half], [], [(a + b)/2],
275
+ # [-(a + b)/2, (a - b)/2, (b - a)/2], t**2))],
276
+ # True)
277
+
278
+ # Section 8.4.21 ?
279
+ # Section 8.4.22
280
+ add(besseli(a, t), [], [(1 + a)/2], [a/2], [-a/2, (1 + a)/2], t**2/4, pi)
281
+ # TODO many more formulas. should all be derivable
282
+
283
+ # Section 8.4.23
284
+ add(besselk(a, t), [], [], [a/2, -a/2], [], t**2/4, S.Half)
285
+ # TODO many more formulas. should all be derivable
286
+
287
+ # Complete elliptic integrals K(z) and E(z)
288
+ add(elliptic_k(t), [S.Half, S.Half], [], [0], [0], -t, S.Half)
289
+ add(elliptic_e(t), [S.Half, 3*S.Half], [], [0], [0], -t, Rational(-1, 2)/2)
290
+
291
+
292
+ ####################################################################
293
+ # First some helper functions.
294
+ ####################################################################
295
+
296
+ from sympy.utilities.timeutils import timethis
297
+ timeit = timethis('meijerg')
298
+
299
+
300
+ def _mytype(f: Basic, x: Symbol) -> tuple[type[Basic], ...]:
301
+ """ Create a hashable entity describing the type of f. """
302
+ def key(x: type[Basic]) -> tuple[int, int, str]:
303
+ return x.class_key()
304
+
305
+ if x not in f.free_symbols:
306
+ return ()
307
+ elif f.is_Function:
308
+ return type(f),
309
+ return tuple(sorted((t for a in f.args for t in _mytype(a, x)), key=key))
310
+
311
+
312
+ class _CoeffExpValueError(ValueError):
313
+ """
314
+ Exception raised by _get_coeff_exp, for internal use only.
315
+ """
316
+ pass
317
+
318
+
319
+ def _get_coeff_exp(expr, x):
320
+ """
321
+ When expr is known to be of the form c*x**b, with c and/or b possibly 1,
322
+ return c, b.
323
+
324
+ Examples
325
+ ========
326
+
327
+ >>> from sympy.abc import x, a, b
328
+ >>> from sympy.integrals.meijerint import _get_coeff_exp
329
+ >>> _get_coeff_exp(a*x**b, x)
330
+ (a, b)
331
+ >>> _get_coeff_exp(x, x)
332
+ (1, 1)
333
+ >>> _get_coeff_exp(2*x, x)
334
+ (2, 1)
335
+ >>> _get_coeff_exp(x**3, x)
336
+ (1, 3)
337
+ """
338
+ from sympy.simplify import powsimp
339
+ (c, m) = expand_power_base(powsimp(expr)).as_coeff_mul(x)
340
+ if not m:
341
+ return c, S.Zero
342
+ [m] = m
343
+ if m.is_Pow:
344
+ if m.base != x:
345
+ raise _CoeffExpValueError('expr not of form a*x**b')
346
+ return c, m.exp
347
+ elif m == x:
348
+ return c, S.One
349
+ else:
350
+ raise _CoeffExpValueError('expr not of form a*x**b: %s' % expr)
351
+
352
+
353
+ def _exponents(expr, x):
354
+ """
355
+ Find the exponents of ``x`` (not including zero) in ``expr``.
356
+
357
+ Examples
358
+ ========
359
+
360
+ >>> from sympy.integrals.meijerint import _exponents
361
+ >>> from sympy.abc import x, y
362
+ >>> from sympy import sin
363
+ >>> _exponents(x, x)
364
+ {1}
365
+ >>> _exponents(x**2, x)
366
+ {2}
367
+ >>> _exponents(x**2 + x, x)
368
+ {1, 2}
369
+ >>> _exponents(x**3*sin(x + x**y) + 1/x, x)
370
+ {-1, 1, 3, y}
371
+ """
372
+ def _exponents_(expr, x, res):
373
+ if expr == x:
374
+ res.update([1])
375
+ return
376
+ if expr.is_Pow and expr.base == x:
377
+ res.update([expr.exp])
378
+ return
379
+ for argument in expr.args:
380
+ _exponents_(argument, x, res)
381
+ res = set()
382
+ _exponents_(expr, x, res)
383
+ return res
384
+
385
+
386
+ def _functions(expr, x):
387
+ """ Find the types of functions in expr, to estimate the complexity. """
388
+ return {e.func for e in expr.atoms(Function) if x in e.free_symbols}
389
+
390
+
391
+ def _find_splitting_points(expr, x):
392
+ """
393
+ Find numbers a such that a linear substitution x -> x + a would
394
+ (hopefully) simplify expr.
395
+
396
+ Examples
397
+ ========
398
+
399
+ >>> from sympy.integrals.meijerint import _find_splitting_points as fsp
400
+ >>> from sympy import sin
401
+ >>> from sympy.abc import x
402
+ >>> fsp(x, x)
403
+ {0}
404
+ >>> fsp((x-1)**3, x)
405
+ {1}
406
+ >>> fsp(sin(x+3)*x, x)
407
+ {-3, 0}
408
+ """
409
+ p, q = [Wild(n, exclude=[x]) for n in 'pq']
410
+
411
+ def compute_innermost(expr, res):
412
+ if not isinstance(expr, Expr):
413
+ return
414
+ m = expr.match(p*x + q)
415
+ if m and m[p] != 0:
416
+ res.add(-m[q]/m[p])
417
+ return
418
+ if expr.is_Atom:
419
+ return
420
+ for argument in expr.args:
421
+ compute_innermost(argument, res)
422
+ innermost = set()
423
+ compute_innermost(expr, innermost)
424
+ return innermost
425
+
426
+
427
+ def _split_mul(f, x):
428
+ """
429
+ Split expression ``f`` into fac, po, g, where fac is a constant factor,
430
+ po = x**s for some s independent of s, and g is "the rest".
431
+
432
+ Examples
433
+ ========
434
+
435
+ >>> from sympy.integrals.meijerint import _split_mul
436
+ >>> from sympy import sin
437
+ >>> from sympy.abc import s, x
438
+ >>> _split_mul((3*x)**s*sin(x**2)*x, x)
439
+ (3**s, x*x**s, sin(x**2))
440
+ """
441
+ fac = S.One
442
+ po = S.One
443
+ g = S.One
444
+ f = expand_power_base(f)
445
+
446
+ args = Mul.make_args(f)
447
+ for a in args:
448
+ if a == x:
449
+ po *= x
450
+ elif x not in a.free_symbols:
451
+ fac *= a
452
+ else:
453
+ if a.is_Pow and x not in a.exp.free_symbols:
454
+ c, t = a.base.as_coeff_mul(x)
455
+ if t != (x,):
456
+ c, t = expand_mul(a.base).as_coeff_mul(x)
457
+ if t == (x,):
458
+ po *= x**a.exp
459
+ fac *= unpolarify(polarify(c**a.exp, subs=False))
460
+ continue
461
+ g *= a
462
+
463
+ return fac, po, g
464
+
465
+
466
+ def _mul_args(f):
467
+ """
468
+ Return a list ``L`` such that ``Mul(*L) == f``.
469
+
470
+ If ``f`` is not a ``Mul`` or ``Pow``, ``L=[f]``.
471
+ If ``f=g**n`` for an integer ``n``, ``L=[g]*n``.
472
+ If ``f`` is a ``Mul``, ``L`` comes from applying ``_mul_args`` to all factors of ``f``.
473
+ """
474
+ args = Mul.make_args(f)
475
+ gs = []
476
+ for g in args:
477
+ if g.is_Pow and g.exp.is_Integer:
478
+ n = g.exp
479
+ base = g.base
480
+ if n < 0:
481
+ n = -n
482
+ base = 1/base
483
+ gs += [base]*n
484
+ else:
485
+ gs.append(g)
486
+ return gs
487
+
488
+
489
+ def _mul_as_two_parts(f):
490
+ """
491
+ Find all the ways to split ``f`` into a product of two terms.
492
+ Return None on failure.
493
+
494
+ Explanation
495
+ ===========
496
+
497
+ Although the order is canonical from multiset_partitions, this is
498
+ not necessarily the best order to process the terms. For example,
499
+ if the case of len(gs) == 2 is removed and multiset is allowed to
500
+ sort the terms, some tests fail.
501
+
502
+ Examples
503
+ ========
504
+
505
+ >>> from sympy.integrals.meijerint import _mul_as_two_parts
506
+ >>> from sympy import sin, exp, ordered
507
+ >>> from sympy.abc import x
508
+ >>> list(ordered(_mul_as_two_parts(x*sin(x)*exp(x))))
509
+ [(x, exp(x)*sin(x)), (x*exp(x), sin(x)), (x*sin(x), exp(x))]
510
+ """
511
+
512
+ gs = _mul_args(f)
513
+ if len(gs) < 2:
514
+ return None
515
+ if len(gs) == 2:
516
+ return [tuple(gs)]
517
+ return [(Mul(*x), Mul(*y)) for (x, y) in multiset_partitions(gs, 2)]
518
+
519
+
520
+ def _inflate_g(g, n):
521
+ """ Return C, h such that h is a G function of argument z**n and
522
+ g = C*h. """
523
+ # TODO should this be a method of meijerg?
524
+ # See: [L, page 150, equation (5)]
525
+ def inflate(params, n):
526
+ """ (a1, .., ak) -> (a1/n, (a1+1)/n, ..., (ak + n-1)/n) """
527
+ return [(a + i)/n for a, i in itertools.product(params, range(n))]
528
+ v = S(len(g.ap) - len(g.bq))
529
+ C = n**(1 + g.nu + v/2)
530
+ C /= (2*pi)**((n - 1)*g.delta)
531
+ return C, meijerg(inflate(g.an, n), inflate(g.aother, n),
532
+ inflate(g.bm, n), inflate(g.bother, n),
533
+ g.argument**n * n**(n*v))
534
+
535
+
536
+ def _flip_g(g):
537
+ """ Turn the G function into one of inverse argument
538
+ (i.e. G(1/x) -> G'(x)) """
539
+ # See [L], section 5.2
540
+ def tr(l):
541
+ return [1 - a for a in l]
542
+ return meijerg(tr(g.bm), tr(g.bother), tr(g.an), tr(g.aother), 1/g.argument)
543
+
544
+
545
+ def _inflate_fox_h(g, a):
546
+ r"""
547
+ Let d denote the integrand in the definition of the G function ``g``.
548
+ Consider the function H which is defined in the same way, but with
549
+ integrand d/Gamma(a*s) (contour conventions as usual).
550
+
551
+ If ``a`` is rational, the function H can be written as C*G, for a constant C
552
+ and a G-function G.
553
+
554
+ This function returns C, G.
555
+ """
556
+ if a < 0:
557
+ return _inflate_fox_h(_flip_g(g), -a)
558
+ p = S(a.p)
559
+ q = S(a.q)
560
+ # We use the substitution s->qs, i.e. inflate g by q. We are left with an
561
+ # extra factor of Gamma(p*s), for which we use Gauss' multiplication
562
+ # theorem.
563
+ D, g = _inflate_g(g, q)
564
+ z = g.argument
565
+ D /= (2*pi)**((1 - p)/2)*p**Rational(-1, 2)
566
+ z /= p**p
567
+ bs = [(n + 1)/p for n in range(p)]
568
+ return D, meijerg(g.an, g.aother, g.bm, list(g.bother) + bs, z)
569
+
570
+ _dummies: dict[tuple[str, str], Dummy] = {}
571
+
572
+
573
+ def _dummy(name, token, expr, **kwargs):
574
+ """
575
+ Return a dummy. This will return the same dummy if the same token+name is
576
+ requested more than once, and it is not already in expr.
577
+ This is for being cache-friendly.
578
+ """
579
+ d = _dummy_(name, token, **kwargs)
580
+ if d in expr.free_symbols:
581
+ return Dummy(name, **kwargs)
582
+ return d
583
+
584
+
585
+ def _dummy_(name, token, **kwargs):
586
+ """
587
+ Return a dummy associated to name and token. Same effect as declaring
588
+ it globally.
589
+ """
590
+ global _dummies
591
+ if not (name, token) in _dummies:
592
+ _dummies[(name, token)] = Dummy(name, **kwargs)
593
+ return _dummies[(name, token)]
594
+
595
+
596
+ def _is_analytic(f, x):
597
+ """ Check if f(x), when expressed using G functions on the positive reals,
598
+ will in fact agree with the G functions almost everywhere """
599
+ return not any(x in expr.free_symbols for expr in f.atoms(Heaviside, Abs))
600
+
601
+
602
+ def _condsimp(cond, first=True):
603
+ """
604
+ Do naive simplifications on ``cond``.
605
+
606
+ Explanation
607
+ ===========
608
+
609
+ Note that this routine is completely ad-hoc, simplification rules being
610
+ added as need arises rather than following any logical pattern.
611
+
612
+ Examples
613
+ ========
614
+
615
+ >>> from sympy.integrals.meijerint import _condsimp as simp
616
+ >>> from sympy import Or, Eq
617
+ >>> from sympy.abc import x, y
618
+ >>> simp(Or(x < y, Eq(x, y)))
619
+ x <= y
620
+ """
621
+ if first:
622
+ cond = cond.replace(lambda _: _.is_Relational, _canonical_coeff)
623
+ first = False
624
+ if not isinstance(cond, BooleanFunction):
625
+ return cond
626
+ p, q, r = symbols('p q r', cls=Wild)
627
+ # transforms tests use 0, 4, 5 and 11-14
628
+ # meijer tests use 0, 2, 11, 14
629
+ # joint_rv uses 6, 7
630
+ rules = [
631
+ (Or(p < q, Eq(p, q)), p <= q), # 0
632
+ # The next two obviously are instances of a general pattern, but it is
633
+ # easier to spell out the few cases we care about.
634
+ (And(Abs(arg(p)) <= pi, Abs(arg(p) - 2*pi) <= pi),
635
+ Eq(arg(p) - pi, 0)), # 1
636
+ (And(Abs(2*arg(p) + pi) <= pi, Abs(2*arg(p) - pi) <= pi),
637
+ Eq(arg(p), 0)), # 2
638
+ (And(Abs(2*arg(p) + pi) < pi, Abs(2*arg(p) - pi) <= pi),
639
+ S.false), # 3
640
+ (And(Abs(arg(p) - pi/2) <= pi/2, Abs(arg(p) + pi/2) <= pi/2),
641
+ Eq(arg(p), 0)), # 4
642
+ (And(Abs(arg(p) - pi/2) <= pi/2, Abs(arg(p) + pi/2) < pi/2),
643
+ S.false), # 5
644
+ (And(Abs(arg(p**2/2 + 1)) < pi, Ne(Abs(arg(p**2/2 + 1)), pi)),
645
+ S.true), # 6
646
+ (Or(Abs(arg(p**2/2 + 1)) < pi, Ne(1/(p**2/2 + 1), 0)),
647
+ S.true), # 7
648
+ (And(Abs(unbranched_argument(p)) <= pi,
649
+ Abs(unbranched_argument(exp_polar(-2*pi*S.ImaginaryUnit)*p)) <= pi),
650
+ Eq(unbranched_argument(exp_polar(-S.ImaginaryUnit*pi)*p), 0)), # 8
651
+ (And(Abs(unbranched_argument(p)) <= pi/2,
652
+ Abs(unbranched_argument(exp_polar(-pi*S.ImaginaryUnit)*p)) <= pi/2),
653
+ Eq(unbranched_argument(exp_polar(-S.ImaginaryUnit*pi/2)*p), 0)), # 9
654
+ (Or(p <= q, And(p < q, r)), p <= q), # 10
655
+ (Ne(p**2, 1) & (p**2 > 1), p**2 > 1), # 11
656
+ (Ne(1/p, 1) & (cos(Abs(arg(p)))*Abs(p) > 1), Abs(p) > 1), # 12
657
+ (Ne(p, 2) & (cos(Abs(arg(p)))*Abs(p) > 2), Abs(p) > 2), # 13
658
+ ((Abs(arg(p)) < pi/2) & (cos(Abs(arg(p)))*sqrt(Abs(p**2)) > 1), p**2 > 1), # 14
659
+ ]
660
+ cond = cond.func(*[_condsimp(_, first) for _ in cond.args])
661
+ change = True
662
+ while change:
663
+ change = False
664
+ for irule, (fro, to) in enumerate(rules):
665
+ if fro.func != cond.func:
666
+ continue
667
+ for n, arg1 in enumerate(cond.args):
668
+ if r in fro.args[0].free_symbols:
669
+ m = arg1.match(fro.args[1])
670
+ num = 1
671
+ else:
672
+ num = 0
673
+ m = arg1.match(fro.args[0])
674
+ if not m:
675
+ continue
676
+ otherargs = [x.subs(m) for x in fro.args[:num] + fro.args[num + 1:]]
677
+ otherlist = [n]
678
+ for arg2 in otherargs:
679
+ for k, arg3 in enumerate(cond.args):
680
+ if k in otherlist:
681
+ continue
682
+ if arg2 == arg3:
683
+ otherlist += [k]
684
+ break
685
+ if isinstance(arg3, And) and arg2.args[1] == r and \
686
+ isinstance(arg2, And) and arg2.args[0] in arg3.args:
687
+ otherlist += [k]
688
+ break
689
+ if isinstance(arg3, And) and arg2.args[0] == r and \
690
+ isinstance(arg2, And) and arg2.args[1] in arg3.args:
691
+ otherlist += [k]
692
+ break
693
+ if len(otherlist) != len(otherargs) + 1:
694
+ continue
695
+ newargs = [arg_ for (k, arg_) in enumerate(cond.args)
696
+ if k not in otherlist] + [to.subs(m)]
697
+ if SYMPY_DEBUG:
698
+ if irule not in (0, 2, 4, 5, 6, 7, 11, 12, 13, 14):
699
+ print('used new rule:', irule)
700
+ cond = cond.func(*newargs)
701
+ change = True
702
+ break
703
+
704
+ # final tweak
705
+ def rel_touchup(rel):
706
+ if rel.rel_op != '==' or rel.rhs != 0:
707
+ return rel
708
+
709
+ # handle Eq(*, 0)
710
+ LHS = rel.lhs
711
+ m = LHS.match(arg(p)**q)
712
+ if not m:
713
+ m = LHS.match(unbranched_argument(polar_lift(p)**q))
714
+ if not m:
715
+ if isinstance(LHS, periodic_argument) and not LHS.args[0].is_polar \
716
+ and LHS.args[1] is S.Infinity:
717
+ return (LHS.args[0] > 0)
718
+ return rel
719
+ return (m[p] > 0)
720
+ cond = cond.replace(lambda _: _.is_Relational, rel_touchup)
721
+ if SYMPY_DEBUG:
722
+ print('_condsimp: ', cond)
723
+ return cond
724
+
725
+ def _eval_cond(cond):
726
+ """ Re-evaluate the conditions. """
727
+ if isinstance(cond, bool):
728
+ return cond
729
+ return _condsimp(cond.doit())
730
+
731
+ ####################################################################
732
+ # Now the "backbone" functions to do actual integration.
733
+ ####################################################################
734
+
735
+
736
+ def _my_principal_branch(expr, period, full_pb=False):
737
+ """ Bring expr nearer to its principal branch by removing superfluous
738
+ factors.
739
+ This function does *not* guarantee to yield the principal branch,
740
+ to avoid introducing opaque principal_branch() objects,
741
+ unless full_pb=True. """
742
+ res = principal_branch(expr, period)
743
+ if not full_pb:
744
+ res = res.replace(principal_branch, lambda x, y: x)
745
+ return res
746
+
747
+
748
+ def _rewrite_saxena_1(fac, po, g, x):
749
+ """
750
+ Rewrite the integral fac*po*g dx, from zero to infinity, as
751
+ integral fac*G, where G has argument a*x. Note po=x**s.
752
+ Return fac, G.
753
+ """
754
+ _, s = _get_coeff_exp(po, x)
755
+ a, b = _get_coeff_exp(g.argument, x)
756
+ period = g.get_period()
757
+ a = _my_principal_branch(a, period)
758
+
759
+ # We substitute t = x**b.
760
+ C = fac/(Abs(b)*a**((s + 1)/b - 1))
761
+ # Absorb a factor of (at)**((1 + s)/b - 1).
762
+
763
+ def tr(l):
764
+ return [a + (1 + s)/b - 1 for a in l]
765
+ return C, meijerg(tr(g.an), tr(g.aother), tr(g.bm), tr(g.bother),
766
+ a*x)
767
+
768
+
769
+ def _check_antecedents_1(g, x, helper=False):
770
+ r"""
771
+ Return a condition under which the mellin transform of g exists.
772
+ Any power of x has already been absorbed into the G function,
773
+ so this is just $\int_0^\infty g\, dx$.
774
+
775
+ See [L, section 5.6.1]. (Note that s=1.)
776
+
777
+ If ``helper`` is True, only check if the MT exists at infinity, i.e. if
778
+ $\int_1^\infty g\, dx$ exists.
779
+ """
780
+ # NOTE if you update these conditions, please update the documentation as well
781
+ delta = g.delta
782
+ eta, _ = _get_coeff_exp(g.argument, x)
783
+ m, n, p, q = S([len(g.bm), len(g.an), len(g.ap), len(g.bq)])
784
+
785
+ if p > q:
786
+ def tr(l):
787
+ return [1 - x for x in l]
788
+ return _check_antecedents_1(meijerg(tr(g.bm), tr(g.bother),
789
+ tr(g.an), tr(g.aother), x/eta),
790
+ x)
791
+
792
+ tmp = [-re(b) < 1 for b in g.bm] + [1 < 1 - re(a) for a in g.an]
793
+ cond_3 = And(*tmp)
794
+
795
+ tmp += [-re(b) < 1 for b in g.bother]
796
+ tmp += [1 < 1 - re(a) for a in g.aother]
797
+ cond_3_star = And(*tmp)
798
+
799
+ cond_4 = (-re(g.nu) + (q + 1 - p)/2 > q - p)
800
+
801
+ def debug(*msg):
802
+ _debug(*msg)
803
+
804
+ def debugf(string, arg):
805
+ _debugf(string, arg)
806
+
807
+ debug('Checking antecedents for 1 function:')
808
+ debugf(' delta=%s, eta=%s, m=%s, n=%s, p=%s, q=%s',
809
+ (delta, eta, m, n, p, q))
810
+ debugf(' ap = %s, %s', (list(g.an), list(g.aother)))
811
+ debugf(' bq = %s, %s', (list(g.bm), list(g.bother)))
812
+ debugf(' cond_3=%s, cond_3*=%s, cond_4=%s', (cond_3, cond_3_star, cond_4))
813
+
814
+ conds = []
815
+
816
+ # case 1
817
+ case1 = []
818
+ tmp1 = [1 <= n, p < q, 1 <= m]
819
+ tmp2 = [1 <= p, 1 <= m, Eq(q, p + 1), Not(And(Eq(n, 0), Eq(m, p + 1)))]
820
+ tmp3 = [1 <= p, Eq(q, p)]
821
+ for k in range(ceiling(delta/2) + 1):
822
+ tmp3 += [Ne(Abs(unbranched_argument(eta)), (delta - 2*k)*pi)]
823
+ tmp = [delta > 0, Abs(unbranched_argument(eta)) < delta*pi]
824
+ extra = [Ne(eta, 0), cond_3]
825
+ if helper:
826
+ extra = []
827
+ for t in [tmp1, tmp2, tmp3]:
828
+ case1 += [And(*(t + tmp + extra))]
829
+ conds += case1
830
+ debug(' case 1:', case1)
831
+
832
+ # case 2
833
+ extra = [cond_3]
834
+ if helper:
835
+ extra = []
836
+ case2 = [And(Eq(n, 0), p + 1 <= m, m <= q,
837
+ Abs(unbranched_argument(eta)) < delta*pi, *extra)]
838
+ conds += case2
839
+ debug(' case 2:', case2)
840
+
841
+ # case 3
842
+ extra = [cond_3, cond_4]
843
+ if helper:
844
+ extra = []
845
+ case3 = [And(p < q, 1 <= m, delta > 0, Eq(Abs(unbranched_argument(eta)), delta*pi),
846
+ *extra)]
847
+ case3 += [And(p <= q - 2, Eq(delta, 0), Eq(Abs(unbranched_argument(eta)), 0), *extra)]
848
+ conds += case3
849
+ debug(' case 3:', case3)
850
+
851
+ # TODO altered cases 4-7
852
+
853
+ # extra case from wofram functions site:
854
+ # (reproduced verbatim from Prudnikov, section 2.24.2)
855
+ # https://functions.wolfram.com/HypergeometricFunctions/MeijerG/21/02/01/
856
+ case_extra = []
857
+ case_extra += [Eq(p, q), Eq(delta, 0), Eq(unbranched_argument(eta), 0), Ne(eta, 0)]
858
+ if not helper:
859
+ case_extra += [cond_3]
860
+ s = []
861
+ for a, b in zip(g.ap, g.bq):
862
+ s += [b - a]
863
+ case_extra += [re(Add(*s)) < 0]
864
+ case_extra = And(*case_extra)
865
+ conds += [case_extra]
866
+ debug(' extra case:', [case_extra])
867
+
868
+ case_extra_2 = [And(delta > 0, Abs(unbranched_argument(eta)) < delta*pi)]
869
+ if not helper:
870
+ case_extra_2 += [cond_3]
871
+ case_extra_2 = And(*case_extra_2)
872
+ conds += [case_extra_2]
873
+ debug(' second extra case:', [case_extra_2])
874
+
875
+ # TODO This leaves only one case from the three listed by Prudnikov.
876
+ # Investigate if these indeed cover everything; if so, remove the rest.
877
+
878
+ return Or(*conds)
879
+
880
+
881
+ def _int0oo_1(g, x):
882
+ r"""
883
+ Evaluate $\int_0^\infty g\, dx$ using G functions,
884
+ assuming the necessary conditions are fulfilled.
885
+
886
+ Examples
887
+ ========
888
+
889
+ >>> from sympy.abc import a, b, c, d, x, y
890
+ >>> from sympy import meijerg
891
+ >>> from sympy.integrals.meijerint import _int0oo_1
892
+ >>> _int0oo_1(meijerg([a], [b], [c], [d], x*y), x)
893
+ gamma(-a)*gamma(c + 1)/(y*gamma(-d)*gamma(b + 1))
894
+ """
895
+ from sympy.simplify import gammasimp
896
+ # See [L, section 5.6.1]. Note that s=1.
897
+ eta, _ = _get_coeff_exp(g.argument, x)
898
+ res = 1/eta
899
+ # XXX TODO we should reduce order first
900
+ for b in g.bm:
901
+ res *= gamma(b + 1)
902
+ for a in g.an:
903
+ res *= gamma(1 - a - 1)
904
+ for b in g.bother:
905
+ res /= gamma(1 - b - 1)
906
+ for a in g.aother:
907
+ res /= gamma(a + 1)
908
+ return gammasimp(unpolarify(res))
909
+
910
+
911
+ def _rewrite_saxena(fac, po, g1, g2, x, full_pb=False):
912
+ """
913
+ Rewrite the integral ``fac*po*g1*g2`` from 0 to oo in terms of G
914
+ functions with argument ``c*x``.
915
+
916
+ Explanation
917
+ ===========
918
+
919
+ Return C, f1, f2 such that integral C f1 f2 from 0 to infinity equals
920
+ integral fac ``po``, ``g1``, ``g2`` from 0 to infinity.
921
+
922
+ Examples
923
+ ========
924
+
925
+ >>> from sympy.integrals.meijerint import _rewrite_saxena
926
+ >>> from sympy.abc import s, t, m
927
+ >>> from sympy import meijerg
928
+ >>> g1 = meijerg([], [], [0], [], s*t)
929
+ >>> g2 = meijerg([], [], [m/2], [-m/2], t**2/4)
930
+ >>> r = _rewrite_saxena(1, t**0, g1, g2, t)
931
+ >>> r[0]
932
+ s/(4*sqrt(pi))
933
+ >>> r[1]
934
+ meijerg(((), ()), ((-1/2, 0), ()), s**2*t/4)
935
+ >>> r[2]
936
+ meijerg(((), ()), ((m/2,), (-m/2,)), t/4)
937
+ """
938
+ def pb(g):
939
+ a, b = _get_coeff_exp(g.argument, x)
940
+ per = g.get_period()
941
+ return meijerg(g.an, g.aother, g.bm, g.bother,
942
+ _my_principal_branch(a, per, full_pb)*x**b)
943
+
944
+ _, s = _get_coeff_exp(po, x)
945
+ _, b1 = _get_coeff_exp(g1.argument, x)
946
+ _, b2 = _get_coeff_exp(g2.argument, x)
947
+ if (b1 < 0) == True:
948
+ b1 = -b1
949
+ g1 = _flip_g(g1)
950
+ if (b2 < 0) == True:
951
+ b2 = -b2
952
+ g2 = _flip_g(g2)
953
+ if not b1.is_Rational or not b2.is_Rational:
954
+ return
955
+ m1, n1 = b1.p, b1.q
956
+ m2, n2 = b2.p, b2.q
957
+ tau = ilcm(m1*n2, m2*n1)
958
+ r1 = tau//(m1*n2)
959
+ r2 = tau//(m2*n1)
960
+
961
+ C1, g1 = _inflate_g(g1, r1)
962
+ C2, g2 = _inflate_g(g2, r2)
963
+ g1 = pb(g1)
964
+ g2 = pb(g2)
965
+
966
+ fac *= C1*C2
967
+ a1, b = _get_coeff_exp(g1.argument, x)
968
+ a2, _ = _get_coeff_exp(g2.argument, x)
969
+
970
+ # arbitrarily tack on the x**s part to g1
971
+ # TODO should we try both?
972
+ exp = (s + 1)/b - 1
973
+ fac = fac/(Abs(b) * a1**exp)
974
+
975
+ def tr(l):
976
+ return [a + exp for a in l]
977
+ g1 = meijerg(tr(g1.an), tr(g1.aother), tr(g1.bm), tr(g1.bother), a1*x)
978
+ g2 = meijerg(g2.an, g2.aother, g2.bm, g2.bother, a2*x)
979
+
980
+ from sympy.simplify import powdenest
981
+ return powdenest(fac, polar=True), g1, g2
982
+
983
+
984
+ def _check_antecedents(g1, g2, x):
985
+ """ Return a condition under which the integral theorem applies. """
986
+ # Yes, this is madness.
987
+ # XXX TODO this is a testing *nightmare*
988
+ # NOTE if you update these conditions, please update the documentation as well
989
+
990
+ # The following conditions are found in
991
+ # [P], Section 2.24.1
992
+ #
993
+ # They are also reproduced (verbatim!) at
994
+ # https://functions.wolfram.com/HypergeometricFunctions/MeijerG/21/02/03/
995
+ #
996
+ # Note: k=l=r=alpha=1
997
+ sigma, _ = _get_coeff_exp(g1.argument, x)
998
+ omega, _ = _get_coeff_exp(g2.argument, x)
999
+ s, t, u, v = S([len(g1.bm), len(g1.an), len(g1.ap), len(g1.bq)])
1000
+ m, n, p, q = S([len(g2.bm), len(g2.an), len(g2.ap), len(g2.bq)])
1001
+ bstar = s + t - (u + v)/2
1002
+ cstar = m + n - (p + q)/2
1003
+ rho = g1.nu + (u - v)/2 + 1
1004
+ mu = g2.nu + (p - q)/2 + 1
1005
+ phi = q - p - (v - u)
1006
+ eta = 1 - (v - u) - mu - rho
1007
+ psi = (pi*(q - m - n) + Abs(unbranched_argument(omega)))/(q - p)
1008
+ theta = (pi*(v - s - t) + Abs(unbranched_argument(sigma)))/(v - u)
1009
+
1010
+ _debug('Checking antecedents:')
1011
+ _debugf(' sigma=%s, s=%s, t=%s, u=%s, v=%s, b*=%s, rho=%s',
1012
+ (sigma, s, t, u, v, bstar, rho))
1013
+ _debugf(' omega=%s, m=%s, n=%s, p=%s, q=%s, c*=%s, mu=%s,',
1014
+ (omega, m, n, p, q, cstar, mu))
1015
+ _debugf(' phi=%s, eta=%s, psi=%s, theta=%s', (phi, eta, psi, theta))
1016
+
1017
+ def _c1():
1018
+ for g in [g1, g2]:
1019
+ for i, j in itertools.product(g.an, g.bm):
1020
+ diff = i - j
1021
+ if diff.is_integer and diff.is_positive:
1022
+ return False
1023
+ return True
1024
+ c1 = _c1()
1025
+ c2 = And(*[re(1 + i + j) > 0 for i in g1.bm for j in g2.bm])
1026
+ c3 = And(*[re(1 + i + j) < 1 + 1 for i in g1.an for j in g2.an])
1027
+ c4 = And(*[(p - q)*re(1 + i - 1) - re(mu) > Rational(-3, 2) for i in g1.an])
1028
+ c5 = And(*[(p - q)*re(1 + i) - re(mu) > Rational(-3, 2) for i in g1.bm])
1029
+ c6 = And(*[(u - v)*re(1 + i - 1) - re(rho) > Rational(-3, 2) for i in g2.an])
1030
+ c7 = And(*[(u - v)*re(1 + i) - re(rho) > Rational(-3, 2) for i in g2.bm])
1031
+ c8 = (Abs(phi) + 2*re((rho - 1)*(q - p) + (v - u)*(q - p) + (mu -
1032
+ 1)*(v - u)) > 0)
1033
+ c9 = (Abs(phi) - 2*re((rho - 1)*(q - p) + (v - u)*(q - p) + (mu -
1034
+ 1)*(v - u)) > 0)
1035
+ c10 = (Abs(unbranched_argument(sigma)) < bstar*pi)
1036
+ c11 = Eq(Abs(unbranched_argument(sigma)), bstar*pi)
1037
+ c12 = (Abs(unbranched_argument(omega)) < cstar*pi)
1038
+ c13 = Eq(Abs(unbranched_argument(omega)), cstar*pi)
1039
+
1040
+ # The following condition is *not* implemented as stated on the wolfram
1041
+ # function site. In the book of Prudnikov there is an additional part
1042
+ # (the And involving re()). However, I only have this book in russian, and
1043
+ # I don't read any russian. The following condition is what other people
1044
+ # have told me it means.
1045
+ # Worryingly, it is different from the condition implemented in REDUCE.
1046
+ # The REDUCE implementation:
1047
+ # https://reduce-algebra.svn.sourceforge.net/svnroot/reduce-algebra/trunk/packages/defint/definta.red
1048
+ # (search for tst14)
1049
+ # The Wolfram alpha version:
1050
+ # https://functions.wolfram.com/HypergeometricFunctions/MeijerG/21/02/03/03/0014/
1051
+ z0 = exp(-(bstar + cstar)*pi*S.ImaginaryUnit)
1052
+ zos = unpolarify(z0*omega/sigma)
1053
+ zso = unpolarify(z0*sigma/omega)
1054
+ if zos == 1/zso:
1055
+ c14 = And(Eq(phi, 0), bstar + cstar <= 1,
1056
+ Or(Ne(zos, 1), re(mu + rho + v - u) < 1,
1057
+ re(mu + rho + q - p) < 1))
1058
+ else:
1059
+ def _cond(z):
1060
+ '''Returns True if abs(arg(1-z)) < pi, avoiding arg(0).
1061
+
1062
+ Explanation
1063
+ ===========
1064
+
1065
+ If ``z`` is 1 then arg is NaN. This raises a
1066
+ TypeError on `NaN < pi`. Previously this gave `False` so
1067
+ this behavior has been hardcoded here but someone should
1068
+ check if this NaN is more serious! This NaN is triggered by
1069
+ test_meijerint() in test_meijerint.py:
1070
+ `meijerint_definite(exp(x), x, 0, I)`
1071
+ '''
1072
+ return z != 1 and Abs(arg(1 - z)) < pi
1073
+
1074
+ c14 = And(Eq(phi, 0), bstar - 1 + cstar <= 0,
1075
+ Or(And(Ne(zos, 1), _cond(zos)),
1076
+ And(re(mu + rho + v - u) < 1, Eq(zos, 1))))
1077
+
1078
+ c14_alt = And(Eq(phi, 0), cstar - 1 + bstar <= 0,
1079
+ Or(And(Ne(zso, 1), _cond(zso)),
1080
+ And(re(mu + rho + q - p) < 1, Eq(zso, 1))))
1081
+
1082
+ # Since r=k=l=1, in our case there is c14_alt which is the same as calling
1083
+ # us with (g1, g2) = (g2, g1). The conditions below enumerate all cases
1084
+ # (i.e. we don't have to try arguments reversed by hand), and indeed try
1085
+ # all symmetric cases. (i.e. whenever there is a condition involving c14,
1086
+ # there is also a dual condition which is exactly what we would get when g1,
1087
+ # g2 were interchanged, *but c14 was unaltered*).
1088
+ # Hence the following seems correct:
1089
+ c14 = Or(c14, c14_alt)
1090
+
1091
+ '''
1092
+ When `c15` is NaN (e.g. from `psi` being NaN as happens during
1093
+ 'test_issue_4992' and/or `theta` is NaN as in 'test_issue_6253',
1094
+ both in `test_integrals.py`) the comparison to 0 formerly gave False
1095
+ whereas now an error is raised. To keep the old behavior, the value
1096
+ of NaN is replaced with False but perhaps a closer look at this condition
1097
+ should be made: XXX how should conditions leading to c15=NaN be handled?
1098
+ '''
1099
+ try:
1100
+ lambda_c = (q - p)*Abs(omega)**(1/(q - p))*cos(psi) \
1101
+ + (v - u)*Abs(sigma)**(1/(v - u))*cos(theta)
1102
+ # the TypeError might be raised here, e.g. if lambda_c is NaN
1103
+ if _eval_cond(lambda_c > 0) != False:
1104
+ c15 = (lambda_c > 0)
1105
+ else:
1106
+ def lambda_s0(c1, c2):
1107
+ return c1*(q - p)*Abs(omega)**(1/(q - p))*sin(psi) \
1108
+ + c2*(v - u)*Abs(sigma)**(1/(v - u))*sin(theta)
1109
+ lambda_s = Piecewise(
1110
+ ((lambda_s0(+1, +1)*lambda_s0(-1, -1)),
1111
+ And(Eq(unbranched_argument(sigma), 0), Eq(unbranched_argument(omega), 0))),
1112
+ (lambda_s0(sign(unbranched_argument(omega)), +1)*lambda_s0(sign(unbranched_argument(omega)), -1),
1113
+ And(Eq(unbranched_argument(sigma), 0), Ne(unbranched_argument(omega), 0))),
1114
+ (lambda_s0(+1, sign(unbranched_argument(sigma)))*lambda_s0(-1, sign(unbranched_argument(sigma))),
1115
+ And(Ne(unbranched_argument(sigma), 0), Eq(unbranched_argument(omega), 0))),
1116
+ (lambda_s0(sign(unbranched_argument(omega)), sign(unbranched_argument(sigma))), True))
1117
+ tmp = [lambda_c > 0,
1118
+ And(Eq(lambda_c, 0), Ne(lambda_s, 0), re(eta) > -1),
1119
+ And(Eq(lambda_c, 0), Eq(lambda_s, 0), re(eta) > 0)]
1120
+ c15 = Or(*tmp)
1121
+ except TypeError:
1122
+ c15 = False
1123
+ for cond, i in [(c1, 1), (c2, 2), (c3, 3), (c4, 4), (c5, 5), (c6, 6),
1124
+ (c7, 7), (c8, 8), (c9, 9), (c10, 10), (c11, 11),
1125
+ (c12, 12), (c13, 13), (c14, 14), (c15, 15)]:
1126
+ _debugf(' c%s: %s', (i, cond))
1127
+
1128
+ # We will return Or(*conds)
1129
+ conds = []
1130
+
1131
+ def pr(count):
1132
+ _debugf(' case %s: %s', (count, conds[-1]))
1133
+ conds += [And(m*n*s*t != 0, bstar.is_positive is True, cstar.is_positive is True, c1, c2, c3, c10,
1134
+ c12)] # 1
1135
+ pr(1)
1136
+ conds += [And(Eq(u, v), Eq(bstar, 0), cstar.is_positive is True, sigma.is_positive is True, re(rho) < 1,
1137
+ c1, c2, c3, c12)] # 2
1138
+ pr(2)
1139
+ conds += [And(Eq(p, q), Eq(cstar, 0), bstar.is_positive is True, omega.is_positive is True, re(mu) < 1,
1140
+ c1, c2, c3, c10)] # 3
1141
+ pr(3)
1142
+ conds += [And(Eq(p, q), Eq(u, v), Eq(bstar, 0), Eq(cstar, 0),
1143
+ sigma.is_positive is True, omega.is_positive is True, re(mu) < 1, re(rho) < 1,
1144
+ Ne(sigma, omega), c1, c2, c3)] # 4
1145
+ pr(4)
1146
+ conds += [And(Eq(p, q), Eq(u, v), Eq(bstar, 0), Eq(cstar, 0),
1147
+ sigma.is_positive is True, omega.is_positive is True, re(mu + rho) < 1,
1148
+ Ne(omega, sigma), c1, c2, c3)] # 5
1149
+ pr(5)
1150
+ conds += [And(p > q, s.is_positive is True, bstar.is_positive is True, cstar >= 0,
1151
+ c1, c2, c3, c5, c10, c13)] # 6
1152
+ pr(6)
1153
+ conds += [And(p < q, t.is_positive is True, bstar.is_positive is True, cstar >= 0,
1154
+ c1, c2, c3, c4, c10, c13)] # 7
1155
+ pr(7)
1156
+ conds += [And(u > v, m.is_positive is True, cstar.is_positive is True, bstar >= 0,
1157
+ c1, c2, c3, c7, c11, c12)] # 8
1158
+ pr(8)
1159
+ conds += [And(u < v, n.is_positive is True, cstar.is_positive is True, bstar >= 0,
1160
+ c1, c2, c3, c6, c11, c12)] # 9
1161
+ pr(9)
1162
+ conds += [And(p > q, Eq(u, v), Eq(bstar, 0), cstar >= 0, sigma.is_positive is True,
1163
+ re(rho) < 1, c1, c2, c3, c5, c13)] # 10
1164
+ pr(10)
1165
+ conds += [And(p < q, Eq(u, v), Eq(bstar, 0), cstar >= 0, sigma.is_positive is True,
1166
+ re(rho) < 1, c1, c2, c3, c4, c13)] # 11
1167
+ pr(11)
1168
+ conds += [And(Eq(p, q), u > v, bstar >= 0, Eq(cstar, 0), omega.is_positive is True,
1169
+ re(mu) < 1, c1, c2, c3, c7, c11)] # 12
1170
+ pr(12)
1171
+ conds += [And(Eq(p, q), u < v, bstar >= 0, Eq(cstar, 0), omega.is_positive is True,
1172
+ re(mu) < 1, c1, c2, c3, c6, c11)] # 13
1173
+ pr(13)
1174
+ conds += [And(p < q, u > v, bstar >= 0, cstar >= 0,
1175
+ c1, c2, c3, c4, c7, c11, c13)] # 14
1176
+ pr(14)
1177
+ conds += [And(p > q, u < v, bstar >= 0, cstar >= 0,
1178
+ c1, c2, c3, c5, c6, c11, c13)] # 15
1179
+ pr(15)
1180
+ conds += [And(p > q, u > v, bstar >= 0, cstar >= 0,
1181
+ c1, c2, c3, c5, c7, c8, c11, c13, c14)] # 16
1182
+ pr(16)
1183
+ conds += [And(p < q, u < v, bstar >= 0, cstar >= 0,
1184
+ c1, c2, c3, c4, c6, c9, c11, c13, c14)] # 17
1185
+ pr(17)
1186
+ conds += [And(Eq(t, 0), s.is_positive is True, bstar.is_positive is True, phi.is_positive is True, c1, c2, c10)] # 18
1187
+ pr(18)
1188
+ conds += [And(Eq(s, 0), t.is_positive is True, bstar.is_positive is True, phi.is_negative is True, c1, c3, c10)] # 19
1189
+ pr(19)
1190
+ conds += [And(Eq(n, 0), m.is_positive is True, cstar.is_positive is True, phi.is_negative is True, c1, c2, c12)] # 20
1191
+ pr(20)
1192
+ conds += [And(Eq(m, 0), n.is_positive is True, cstar.is_positive is True, phi.is_positive is True, c1, c3, c12)] # 21
1193
+ pr(21)
1194
+ conds += [And(Eq(s*t, 0), bstar.is_positive is True, cstar.is_positive is True,
1195
+ c1, c2, c3, c10, c12)] # 22
1196
+ pr(22)
1197
+ conds += [And(Eq(m*n, 0), bstar.is_positive is True, cstar.is_positive is True,
1198
+ c1, c2, c3, c10, c12)] # 23
1199
+ pr(23)
1200
+
1201
+ # The following case is from [Luke1969]. As far as I can tell, it is *not*
1202
+ # covered by Prudnikov's.
1203
+ # Let G1 and G2 be the two G-functions. Suppose the integral exists from
1204
+ # 0 to a > 0 (this is easy the easy part), that G1 is exponential decay at
1205
+ # infinity, and that the mellin transform of G2 exists.
1206
+ # Then the integral exists.
1207
+ mt1_exists = _check_antecedents_1(g1, x, helper=True)
1208
+ mt2_exists = _check_antecedents_1(g2, x, helper=True)
1209
+ conds += [And(mt2_exists, Eq(t, 0), u < s, bstar.is_positive is True, c10, c1, c2, c3)]
1210
+ pr('E1')
1211
+ conds += [And(mt2_exists, Eq(s, 0), v < t, bstar.is_positive is True, c10, c1, c2, c3)]
1212
+ pr('E2')
1213
+ conds += [And(mt1_exists, Eq(n, 0), p < m, cstar.is_positive is True, c12, c1, c2, c3)]
1214
+ pr('E3')
1215
+ conds += [And(mt1_exists, Eq(m, 0), q < n, cstar.is_positive is True, c12, c1, c2, c3)]
1216
+ pr('E4')
1217
+
1218
+ # Let's short-circuit if this worked ...
1219
+ # the rest is corner-cases and terrible to read.
1220
+ r = Or(*conds)
1221
+ if _eval_cond(r) != False:
1222
+ return r
1223
+
1224
+ conds += [And(m + n > p, Eq(t, 0), Eq(phi, 0), s.is_positive is True, bstar.is_positive is True, cstar.is_negative is True,
1225
+ Abs(unbranched_argument(omega)) < (m + n - p + 1)*pi,
1226
+ c1, c2, c10, c14, c15)] # 24
1227
+ pr(24)
1228
+ conds += [And(m + n > q, Eq(s, 0), Eq(phi, 0), t.is_positive is True, bstar.is_positive is True, cstar.is_negative is True,
1229
+ Abs(unbranched_argument(omega)) < (m + n - q + 1)*pi,
1230
+ c1, c3, c10, c14, c15)] # 25
1231
+ pr(25)
1232
+ conds += [And(Eq(p, q - 1), Eq(t, 0), Eq(phi, 0), s.is_positive is True, bstar.is_positive is True,
1233
+ cstar >= 0, cstar*pi < Abs(unbranched_argument(omega)),
1234
+ c1, c2, c10, c14, c15)] # 26
1235
+ pr(26)
1236
+ conds += [And(Eq(p, q + 1), Eq(s, 0), Eq(phi, 0), t.is_positive is True, bstar.is_positive is True,
1237
+ cstar >= 0, cstar*pi < Abs(unbranched_argument(omega)),
1238
+ c1, c3, c10, c14, c15)] # 27
1239
+ pr(27)
1240
+ conds += [And(p < q - 1, Eq(t, 0), Eq(phi, 0), s.is_positive is True, bstar.is_positive is True,
1241
+ cstar >= 0, cstar*pi < Abs(unbranched_argument(omega)),
1242
+ Abs(unbranched_argument(omega)) < (m + n - p + 1)*pi,
1243
+ c1, c2, c10, c14, c15)] # 28
1244
+ pr(28)
1245
+ conds += [And(
1246
+ p > q + 1, Eq(s, 0), Eq(phi, 0), t.is_positive is True, bstar.is_positive is True, cstar >= 0,
1247
+ cstar*pi < Abs(unbranched_argument(omega)),
1248
+ Abs(unbranched_argument(omega)) < (m + n - q + 1)*pi,
1249
+ c1, c3, c10, c14, c15)] # 29
1250
+ pr(29)
1251
+ conds += [And(Eq(n, 0), Eq(phi, 0), s + t > 0, m.is_positive is True, cstar.is_positive is True, bstar.is_negative is True,
1252
+ Abs(unbranched_argument(sigma)) < (s + t - u + 1)*pi,
1253
+ c1, c2, c12, c14, c15)] # 30
1254
+ pr(30)
1255
+ conds += [And(Eq(m, 0), Eq(phi, 0), s + t > v, n.is_positive is True, cstar.is_positive is True, bstar.is_negative is True,
1256
+ Abs(unbranched_argument(sigma)) < (s + t - v + 1)*pi,
1257
+ c1, c3, c12, c14, c15)] # 31
1258
+ pr(31)
1259
+ conds += [And(Eq(n, 0), Eq(phi, 0), Eq(u, v - 1), m.is_positive is True, cstar.is_positive is True,
1260
+ bstar >= 0, bstar*pi < Abs(unbranched_argument(sigma)),
1261
+ Abs(unbranched_argument(sigma)) < (bstar + 1)*pi,
1262
+ c1, c2, c12, c14, c15)] # 32
1263
+ pr(32)
1264
+ conds += [And(Eq(m, 0), Eq(phi, 0), Eq(u, v + 1), n.is_positive is True, cstar.is_positive is True,
1265
+ bstar >= 0, bstar*pi < Abs(unbranched_argument(sigma)),
1266
+ Abs(unbranched_argument(sigma)) < (bstar + 1)*pi,
1267
+ c1, c3, c12, c14, c15)] # 33
1268
+ pr(33)
1269
+ conds += [And(
1270
+ Eq(n, 0), Eq(phi, 0), u < v - 1, m.is_positive is True, cstar.is_positive is True, bstar >= 0,
1271
+ bstar*pi < Abs(unbranched_argument(sigma)),
1272
+ Abs(unbranched_argument(sigma)) < (s + t - u + 1)*pi,
1273
+ c1, c2, c12, c14, c15)] # 34
1274
+ pr(34)
1275
+ conds += [And(
1276
+ Eq(m, 0), Eq(phi, 0), u > v + 1, n.is_positive is True, cstar.is_positive is True, bstar >= 0,
1277
+ bstar*pi < Abs(unbranched_argument(sigma)),
1278
+ Abs(unbranched_argument(sigma)) < (s + t - v + 1)*pi,
1279
+ c1, c3, c12, c14, c15)] # 35
1280
+ pr(35)
1281
+
1282
+ return Or(*conds)
1283
+
1284
+ # NOTE An alternative, but as far as I can tell weaker, set of conditions
1285
+ # can be found in [L, section 5.6.2].
1286
+
1287
+
1288
+ def _int0oo(g1, g2, x):
1289
+ """
1290
+ Express integral from zero to infinity g1*g2 using a G function,
1291
+ assuming the necessary conditions are fulfilled.
1292
+
1293
+ Examples
1294
+ ========
1295
+
1296
+ >>> from sympy.integrals.meijerint import _int0oo
1297
+ >>> from sympy.abc import s, t, m
1298
+ >>> from sympy import meijerg, S
1299
+ >>> g1 = meijerg([], [], [-S(1)/2, 0], [], s**2*t/4)
1300
+ >>> g2 = meijerg([], [], [m/2], [-m/2], t/4)
1301
+ >>> _int0oo(g1, g2, t)
1302
+ 4*meijerg(((1/2, 0), ()), ((m/2,), (-m/2,)), s**(-2))/s**2
1303
+ """
1304
+ # See: [L, section 5.6.2, equation (1)]
1305
+ eta, _ = _get_coeff_exp(g1.argument, x)
1306
+ omega, _ = _get_coeff_exp(g2.argument, x)
1307
+
1308
+ def neg(l):
1309
+ return [-x for x in l]
1310
+ a1 = neg(g1.bm) + list(g2.an)
1311
+ a2 = list(g2.aother) + neg(g1.bother)
1312
+ b1 = neg(g1.an) + list(g2.bm)
1313
+ b2 = list(g2.bother) + neg(g1.aother)
1314
+ return meijerg(a1, a2, b1, b2, omega/eta)/eta
1315
+
1316
+
1317
+ def _rewrite_inversion(fac, po, g, x):
1318
+ """ Absorb ``po`` == x**s into g. """
1319
+ _, s = _get_coeff_exp(po, x)
1320
+ a, b = _get_coeff_exp(g.argument, x)
1321
+
1322
+ def tr(l):
1323
+ return [t + s/b for t in l]
1324
+ from sympy.simplify import powdenest
1325
+ return (powdenest(fac/a**(s/b), polar=True),
1326
+ meijerg(tr(g.an), tr(g.aother), tr(g.bm), tr(g.bother), g.argument))
1327
+
1328
+
1329
+ def _check_antecedents_inversion(g, x):
1330
+ """ Check antecedents for the laplace inversion integral. """
1331
+ _debug('Checking antecedents for inversion:')
1332
+ z = g.argument
1333
+ _, e = _get_coeff_exp(z, x)
1334
+ if e < 0:
1335
+ _debug(' Flipping G.')
1336
+ # We want to assume that argument gets large as |x| -> oo
1337
+ return _check_antecedents_inversion(_flip_g(g), x)
1338
+
1339
+ def statement_half(a, b, c, z, plus):
1340
+ coeff, exponent = _get_coeff_exp(z, x)
1341
+ a *= exponent
1342
+ b *= coeff**c
1343
+ c *= exponent
1344
+ conds = []
1345
+ wp = b*exp(S.ImaginaryUnit*re(c)*pi/2)
1346
+ wm = b*exp(-S.ImaginaryUnit*re(c)*pi/2)
1347
+ if plus:
1348
+ w = wp
1349
+ else:
1350
+ w = wm
1351
+ conds += [And(Or(Eq(b, 0), re(c) <= 0), re(a) <= -1)]
1352
+ conds += [And(Ne(b, 0), Eq(im(c), 0), re(c) > 0, re(w) < 0)]
1353
+ conds += [And(Ne(b, 0), Eq(im(c), 0), re(c) > 0, re(w) <= 0,
1354
+ re(a) <= -1)]
1355
+ return Or(*conds)
1356
+
1357
+ def statement(a, b, c, z):
1358
+ """ Provide a convergence statement for z**a * exp(b*z**c),
1359
+ c/f sphinx docs. """
1360
+ return And(statement_half(a, b, c, z, True),
1361
+ statement_half(a, b, c, z, False))
1362
+
1363
+ # Notations from [L], section 5.7-10
1364
+ m, n, p, q = S([len(g.bm), len(g.an), len(g.ap), len(g.bq)])
1365
+ tau = m + n - p
1366
+ nu = q - m - n
1367
+ rho = (tau - nu)/2
1368
+ sigma = q - p
1369
+ if sigma == 1:
1370
+ epsilon = S.Half
1371
+ elif sigma > 1:
1372
+ epsilon = 1
1373
+ else:
1374
+ epsilon = S.NaN
1375
+ theta = ((1 - sigma)/2 + Add(*g.bq) - Add(*g.ap))/sigma
1376
+ delta = g.delta
1377
+ _debugf(' m=%s, n=%s, p=%s, q=%s, tau=%s, nu=%s, rho=%s, sigma=%s',
1378
+ (m, n, p, q, tau, nu, rho, sigma))
1379
+ _debugf(' epsilon=%s, theta=%s, delta=%s', (epsilon, theta, delta))
1380
+
1381
+ # First check if the computation is valid.
1382
+ if not (g.delta >= e/2 or (p >= 1 and p >= q)):
1383
+ _debug(' Computation not valid for these parameters.')
1384
+ return False
1385
+
1386
+ # Now check if the inversion integral exists.
1387
+
1388
+ # Test "condition A"
1389
+ for a, b in itertools.product(g.an, g.bm):
1390
+ if (a - b).is_integer and a > b:
1391
+ _debug(' Not a valid G function.')
1392
+ return False
1393
+
1394
+ # There are two cases. If p >= q, we can directly use a slater expansion
1395
+ # like [L], 5.2 (11). Note in particular that the asymptotics of such an
1396
+ # expansion even hold when some of the parameters differ by integers, i.e.
1397
+ # the formula itself would not be valid! (b/c G functions are cts. in their
1398
+ # parameters)
1399
+ # When p < q, we need to use the theorems of [L], 5.10.
1400
+
1401
+ if p >= q:
1402
+ _debug(' Using asymptotic Slater expansion.')
1403
+ return And(*[statement(a - 1, 0, 0, z) for a in g.an])
1404
+
1405
+ def E(z):
1406
+ return And(*[statement(a - 1, 0, 0, z) for a in g.an])
1407
+
1408
+ def H(z):
1409
+ return statement(theta, -sigma, 1/sigma, z)
1410
+
1411
+ def Hp(z):
1412
+ return statement_half(theta, -sigma, 1/sigma, z, True)
1413
+
1414
+ def Hm(z):
1415
+ return statement_half(theta, -sigma, 1/sigma, z, False)
1416
+
1417
+ # [L], section 5.10
1418
+ conds = []
1419
+ # Theorem 1 -- p < q from test above
1420
+ conds += [And(1 <= n, 1 <= m, rho*pi - delta >= pi/2, delta > 0,
1421
+ E(z*exp(S.ImaginaryUnit*pi*(nu + 1))))]
1422
+ # Theorem 2, statements (2) and (3)
1423
+ conds += [And(p + 1 <= m, m + 1 <= q, delta > 0, delta < pi/2, n == 0,
1424
+ (m - p + 1)*pi - delta >= pi/2,
1425
+ Hp(z*exp(S.ImaginaryUnit*pi*(q - m))),
1426
+ Hm(z*exp(-S.ImaginaryUnit*pi*(q - m))))]
1427
+ # Theorem 2, statement (5) -- p < q from test above
1428
+ conds += [And(m == q, n == 0, delta > 0,
1429
+ (sigma + epsilon)*pi - delta >= pi/2, H(z))]
1430
+ # Theorem 3, statements (6) and (7)
1431
+ conds += [And(Or(And(p <= q - 2, 1 <= tau, tau <= sigma/2),
1432
+ And(p + 1 <= m + n, m + n <= (p + q)/2)),
1433
+ delta > 0, delta < pi/2, (tau + 1)*pi - delta >= pi/2,
1434
+ Hp(z*exp(S.ImaginaryUnit*pi*nu)),
1435
+ Hm(z*exp(-S.ImaginaryUnit*pi*nu)))]
1436
+ # Theorem 4, statements (10) and (11) -- p < q from test above
1437
+ conds += [And(1 <= m, rho > 0, delta > 0, delta + rho*pi < pi/2,
1438
+ (tau + epsilon)*pi - delta >= pi/2,
1439
+ Hp(z*exp(S.ImaginaryUnit*pi*nu)),
1440
+ Hm(z*exp(-S.ImaginaryUnit*pi*nu)))]
1441
+ # Trivial case
1442
+ conds += [m == 0]
1443
+
1444
+ # TODO
1445
+ # Theorem 5 is quite general
1446
+ # Theorem 6 contains special cases for q=p+1
1447
+
1448
+ return Or(*conds)
1449
+
1450
+
1451
+ def _int_inversion(g, x, t):
1452
+ """
1453
+ Compute the laplace inversion integral, assuming the formula applies.
1454
+ """
1455
+ b, a = _get_coeff_exp(g.argument, x)
1456
+ C, g = _inflate_fox_h(meijerg(g.an, g.aother, g.bm, g.bother, b/t**a), -a)
1457
+ return C/t*g
1458
+
1459
+
1460
+ ####################################################################
1461
+ # Finally, the real meat.
1462
+ ####################################################################
1463
+
1464
+ _lookup_table = None
1465
+
1466
+
1467
+ @cacheit
1468
+ @timeit
1469
+ def _rewrite_single(f, x, recursive=True):
1470
+ """
1471
+ Try to rewrite f as a sum of single G functions of the form
1472
+ C*x**s*G(a*x**b), where b is a rational number and C is independent of x.
1473
+ We guarantee that result.argument.as_coeff_mul(x) returns (a, (x**b,))
1474
+ or (a, ()).
1475
+ Returns a list of tuples (C, s, G) and a condition cond.
1476
+ Returns None on failure.
1477
+ """
1478
+ from .transforms import (mellin_transform, inverse_mellin_transform,
1479
+ IntegralTransformError, MellinTransformStripError)
1480
+
1481
+ global _lookup_table
1482
+ if not _lookup_table:
1483
+ _lookup_table = {}
1484
+ _create_lookup_table(_lookup_table)
1485
+
1486
+ if isinstance(f, meijerg):
1487
+ coeff, m = factor(f.argument, x).as_coeff_mul(x)
1488
+ if len(m) > 1:
1489
+ return None
1490
+ m = m[0]
1491
+ if m.is_Pow:
1492
+ if m.base != x or not m.exp.is_Rational:
1493
+ return None
1494
+ elif m != x:
1495
+ return None
1496
+ return [(1, 0, meijerg(f.an, f.aother, f.bm, f.bother, coeff*m))], True
1497
+
1498
+ f_ = f
1499
+ f = f.subs(x, z)
1500
+ t = _mytype(f, z)
1501
+ if t in _lookup_table:
1502
+ l = _lookup_table[t]
1503
+ for formula, terms, cond, hint in l:
1504
+ subs = f.match(formula, old=True)
1505
+ if subs:
1506
+ subs_ = {}
1507
+ for fro, to in subs.items():
1508
+ subs_[fro] = unpolarify(polarify(to, lift=True),
1509
+ exponents_only=True)
1510
+ subs = subs_
1511
+ if not isinstance(hint, bool):
1512
+ hint = hint.subs(subs)
1513
+ if hint == False:
1514
+ continue
1515
+ if not isinstance(cond, (bool, BooleanAtom)):
1516
+ cond = unpolarify(cond.subs(subs))
1517
+ if _eval_cond(cond) == False:
1518
+ continue
1519
+ if not isinstance(terms, list):
1520
+ terms = terms(subs)
1521
+ res = []
1522
+ for fac, g in terms:
1523
+ r1 = _get_coeff_exp(unpolarify(fac.subs(subs).subs(z, x),
1524
+ exponents_only=True), x)
1525
+ try:
1526
+ g = g.subs(subs).subs(z, x)
1527
+ except ValueError:
1528
+ continue
1529
+ # NOTE these substitutions can in principle introduce oo,
1530
+ # zoo and other absurdities. It shouldn't matter,
1531
+ # but better be safe.
1532
+ if Tuple(*(r1 + (g,))).has(S.Infinity, S.ComplexInfinity, S.NegativeInfinity):
1533
+ continue
1534
+ g = meijerg(g.an, g.aother, g.bm, g.bother,
1535
+ unpolarify(g.argument, exponents_only=True))
1536
+ res.append(r1 + (g,))
1537
+ if res:
1538
+ return res, cond
1539
+
1540
+ # try recursive mellin transform
1541
+ if not recursive:
1542
+ return None
1543
+ _debug('Trying recursive Mellin transform method.')
1544
+
1545
+ def my_imt(F, s, x, strip):
1546
+ """ Calling simplify() all the time is slow and not helpful, since
1547
+ most of the time it only factors things in a way that has to be
1548
+ un-done anyway. But sometimes it can remove apparent poles. """
1549
+ # XXX should this be in inverse_mellin_transform?
1550
+ try:
1551
+ return inverse_mellin_transform(F, s, x, strip,
1552
+ as_meijerg=True, needeval=True)
1553
+ except MellinTransformStripError:
1554
+ from sympy.simplify import simplify
1555
+ return inverse_mellin_transform(
1556
+ simplify(cancel(expand(F))), s, x, strip,
1557
+ as_meijerg=True, needeval=True)
1558
+ f = f_
1559
+ s = _dummy('s', 'rewrite-single', f)
1560
+ # to avoid infinite recursion, we have to force the two g functions case
1561
+
1562
+ def my_integrator(f, x):
1563
+ r = _meijerint_definite_4(f, x, only_double=True)
1564
+ if r is not None:
1565
+ from sympy.simplify import hyperexpand
1566
+ res, cond = r
1567
+ res = _my_unpolarify(hyperexpand(res, rewrite='nonrepsmall'))
1568
+ return Piecewise((res, cond),
1569
+ (Integral(f, (x, S.Zero, S.Infinity)), True))
1570
+ return Integral(f, (x, S.Zero, S.Infinity))
1571
+ try:
1572
+ F, strip, _ = mellin_transform(f, x, s, integrator=my_integrator,
1573
+ simplify=False, needeval=True)
1574
+ g = my_imt(F, s, x, strip)
1575
+ except IntegralTransformError:
1576
+ g = None
1577
+ if g is None:
1578
+ # We try to find an expression by analytic continuation.
1579
+ # (also if the dummy is already in the expression, there is no point in
1580
+ # putting in another one)
1581
+ a = _dummy_('a', 'rewrite-single')
1582
+ if a not in f.free_symbols and _is_analytic(f, x):
1583
+ try:
1584
+ F, strip, _ = mellin_transform(f.subs(x, a*x), x, s,
1585
+ integrator=my_integrator,
1586
+ needeval=True, simplify=False)
1587
+ g = my_imt(F, s, x, strip).subs(a, 1)
1588
+ except IntegralTransformError:
1589
+ g = None
1590
+ if g is None or g.has(S.Infinity, S.NaN, S.ComplexInfinity):
1591
+ _debug('Recursive Mellin transform failed.')
1592
+ return None
1593
+ args = Add.make_args(g)
1594
+ res = []
1595
+ for f in args:
1596
+ c, m = f.as_coeff_mul(x)
1597
+ if len(m) > 1:
1598
+ raise NotImplementedError('Unexpected form...')
1599
+ g = m[0]
1600
+ a, b = _get_coeff_exp(g.argument, x)
1601
+ res += [(c, 0, meijerg(g.an, g.aother, g.bm, g.bother,
1602
+ unpolarify(polarify(
1603
+ a, lift=True), exponents_only=True)
1604
+ *x**b))]
1605
+ _debug('Recursive Mellin transform worked:', g)
1606
+ return res, True
1607
+
1608
+
1609
+ def _rewrite1(f, x, recursive=True):
1610
+ """
1611
+ Try to rewrite ``f`` using a (sum of) single G functions with argument a*x**b.
1612
+ Return fac, po, g such that f = fac*po*g, fac is independent of ``x``.
1613
+ and po = x**s.
1614
+ Here g is a result from _rewrite_single.
1615
+ Return None on failure.
1616
+ """
1617
+ fac, po, g = _split_mul(f, x)
1618
+ g = _rewrite_single(g, x, recursive)
1619
+ if g:
1620
+ return fac, po, g[0], g[1]
1621
+
1622
+
1623
+ def _rewrite2(f, x):
1624
+ """
1625
+ Try to rewrite ``f`` as a product of two G functions of arguments a*x**b.
1626
+ Return fac, po, g1, g2 such that f = fac*po*g1*g2, where fac is
1627
+ independent of x and po is x**s.
1628
+ Here g1 and g2 are results of _rewrite_single.
1629
+ Returns None on failure.
1630
+ """
1631
+ fac, po, g = _split_mul(f, x)
1632
+ if any(_rewrite_single(expr, x, False) is None for expr in _mul_args(g)):
1633
+ return None
1634
+ l = _mul_as_two_parts(g)
1635
+ if not l:
1636
+ return None
1637
+ l = list(ordered(l, [
1638
+ lambda p: max(len(_exponents(p[0], x)), len(_exponents(p[1], x))),
1639
+ lambda p: max(len(_functions(p[0], x)), len(_functions(p[1], x))),
1640
+ lambda p: max(len(_find_splitting_points(p[0], x)),
1641
+ len(_find_splitting_points(p[1], x)))]))
1642
+
1643
+ for recursive, (fac1, fac2) in itertools.product((False, True), l):
1644
+ g1 = _rewrite_single(fac1, x, recursive)
1645
+ g2 = _rewrite_single(fac2, x, recursive)
1646
+ if g1 and g2:
1647
+ cond = And(g1[1], g2[1])
1648
+ if cond != False:
1649
+ return fac, po, g1[0], g2[0], cond
1650
+
1651
+
1652
+ def meijerint_indefinite(f, x):
1653
+ """
1654
+ Compute an indefinite integral of ``f`` by rewriting it as a G function.
1655
+
1656
+ Examples
1657
+ ========
1658
+
1659
+ >>> from sympy.integrals.meijerint import meijerint_indefinite
1660
+ >>> from sympy import sin
1661
+ >>> from sympy.abc import x
1662
+ >>> meijerint_indefinite(sin(x), x)
1663
+ -cos(x)
1664
+ """
1665
+ f = sympify(f)
1666
+ results = []
1667
+ for a in sorted(_find_splitting_points(f, x) | {S.Zero}, key=default_sort_key):
1668
+ res = _meijerint_indefinite_1(f.subs(x, x + a), x)
1669
+ if not res:
1670
+ continue
1671
+ res = res.subs(x, x - a)
1672
+ if _has(res, hyper, meijerg):
1673
+ results.append(res)
1674
+ else:
1675
+ return res
1676
+ if f.has(HyperbolicFunction):
1677
+ _debug('Try rewriting hyperbolics in terms of exp.')
1678
+ rv = meijerint_indefinite(
1679
+ _rewrite_hyperbolics_as_exp(f), x)
1680
+ if rv:
1681
+ if not isinstance(rv, list):
1682
+ from sympy.simplify.radsimp import collect
1683
+ return collect(factor_terms(rv), rv.atoms(exp))
1684
+ results.extend(rv)
1685
+ if results:
1686
+ return next(ordered(results))
1687
+
1688
+
1689
+ def _meijerint_indefinite_1(f, x):
1690
+ """ Helper that does not attempt any substitution. """
1691
+ _debug('Trying to compute the indefinite integral of', f, 'wrt', x)
1692
+ from sympy.simplify import hyperexpand, powdenest
1693
+
1694
+ gs = _rewrite1(f, x)
1695
+ if gs is None:
1696
+ # Note: the code that calls us will do expand() and try again
1697
+ return None
1698
+
1699
+ fac, po, gl, cond = gs
1700
+ _debug(' could rewrite:', gs)
1701
+ res = S.Zero
1702
+ for C, s, g in gl:
1703
+ a, b = _get_coeff_exp(g.argument, x)
1704
+ _, c = _get_coeff_exp(po, x)
1705
+ c += s
1706
+
1707
+ # we do a substitution t=a*x**b, get integrand fac*t**rho*g
1708
+ fac_ = fac * C / (b*a**((1 + c)/b))
1709
+ rho = (c + 1)/b - 1
1710
+
1711
+ # we now use t**rho*G(params, t) = G(params + rho, t)
1712
+ # [L, page 150, equation (4)]
1713
+ # and integral G(params, t) dt = G(1, params+1, 0, t)
1714
+ # (or a similar expression with 1 and 0 exchanged ... pick the one
1715
+ # which yields a well-defined function)
1716
+ # [R, section 5]
1717
+ # (Note that this dummy will immediately go away again, so we
1718
+ # can safely pass S.One for ``expr``.)
1719
+ t = _dummy('t', 'meijerint-indefinite', S.One)
1720
+
1721
+ def tr(p):
1722
+ return [a + rho + 1 for a in p]
1723
+ if any(b.is_integer and (b <= 0) == True for b in tr(g.bm)):
1724
+ r = -meijerg(
1725
+ tr(g.an), tr(g.aother) + [1], tr(g.bm) + [0], tr(g.bother), t)
1726
+ else:
1727
+ r = meijerg(
1728
+ tr(g.an) + [1], tr(g.aother), tr(g.bm), tr(g.bother) + [0], t)
1729
+ # The antiderivative is most often expected to be defined
1730
+ # in the neighborhood of x = 0.
1731
+ if b.is_extended_nonnegative and not f.subs(x, 0).has(S.NaN, S.ComplexInfinity):
1732
+ place = 0 # Assume we can expand at zero
1733
+ else:
1734
+ place = None
1735
+ r = hyperexpand(r.subs(t, a*x**b), place=place)
1736
+
1737
+ # now substitute back
1738
+ # Note: we really do want the powers of x to combine.
1739
+ res += powdenest(fac_*r, polar=True)
1740
+
1741
+ def _clean(res):
1742
+ """This multiplies out superfluous powers of x we created, and chops off
1743
+ constants:
1744
+
1745
+ >> _clean(x*(exp(x)/x - 1/x) + 3)
1746
+ exp(x)
1747
+
1748
+ cancel is used before mul_expand since it is possible for an
1749
+ expression to have an additive constant that does not become isolated
1750
+ with simple expansion. Such a situation was identified in issue 6369:
1751
+
1752
+ Examples
1753
+ ========
1754
+
1755
+ >>> from sympy import sqrt, cancel
1756
+ >>> from sympy.abc import x
1757
+ >>> a = sqrt(2*x + 1)
1758
+ >>> bad = (3*x*a**5 + 2*x - a**5 + 1)/a**2
1759
+ >>> bad.expand().as_independent(x)[0]
1760
+ 0
1761
+ >>> cancel(bad).expand().as_independent(x)[0]
1762
+ 1
1763
+ """
1764
+ res = expand_mul(cancel(res), deep=False)
1765
+ return Add._from_args(res.as_coeff_add(x)[1])
1766
+
1767
+ res = piecewise_fold(res, evaluate=None)
1768
+ if res.is_Piecewise:
1769
+ newargs = []
1770
+ for e, c in res.args:
1771
+ e = _my_unpolarify(_clean(e))
1772
+ newargs += [(e, c)]
1773
+ res = Piecewise(*newargs, evaluate=False)
1774
+ else:
1775
+ res = _my_unpolarify(_clean(res))
1776
+ return Piecewise((res, _my_unpolarify(cond)), (Integral(f, x), True))
1777
+
1778
+
1779
+ @timeit
1780
+ def meijerint_definite(f, x, a, b):
1781
+ """
1782
+ Integrate ``f`` over the interval [``a``, ``b``], by rewriting it as a product
1783
+ of two G functions, or as a single G function.
1784
+
1785
+ Return res, cond, where cond are convergence conditions.
1786
+
1787
+ Examples
1788
+ ========
1789
+
1790
+ >>> from sympy.integrals.meijerint import meijerint_definite
1791
+ >>> from sympy import exp, oo
1792
+ >>> from sympy.abc import x
1793
+ >>> meijerint_definite(exp(-x**2), x, -oo, oo)
1794
+ (sqrt(pi), True)
1795
+
1796
+ This function is implemented as a succession of functions
1797
+ meijerint_definite, _meijerint_definite_2, _meijerint_definite_3,
1798
+ _meijerint_definite_4. Each function in the list calls the next one
1799
+ (presumably) several times. This means that calling meijerint_definite
1800
+ can be very costly.
1801
+ """
1802
+ # This consists of three steps:
1803
+ # 1) Change the integration limits to 0, oo
1804
+ # 2) Rewrite in terms of G functions
1805
+ # 3) Evaluate the integral
1806
+ #
1807
+ # There are usually several ways of doing this, and we want to try all.
1808
+ # This function does (1), calls _meijerint_definite_2 for step (2).
1809
+ _debugf('Integrating %s wrt %s from %s to %s.', (f, x, a, b))
1810
+ f = sympify(f)
1811
+ if f.has(DiracDelta):
1812
+ _debug('Integrand has DiracDelta terms - giving up.')
1813
+ return None
1814
+
1815
+ if f.has(SingularityFunction):
1816
+ _debug('Integrand has Singularity Function terms - giving up.')
1817
+ return None
1818
+
1819
+ f_, x_, a_, b_ = f, x, a, b
1820
+
1821
+ # Let's use a dummy in case any of the boundaries has x.
1822
+ d = Dummy('x')
1823
+ f = f.subs(x, d)
1824
+ x = d
1825
+
1826
+ if a == b:
1827
+ return (S.Zero, True)
1828
+
1829
+ results = []
1830
+ if a is S.NegativeInfinity and b is not S.Infinity:
1831
+ return meijerint_definite(f.subs(x, -x), x, -b, -a)
1832
+
1833
+ elif a is S.NegativeInfinity:
1834
+ # Integrating -oo to oo. We need to find a place to split the integral.
1835
+ _debug(' Integrating -oo to +oo.')
1836
+ innermost = _find_splitting_points(f, x)
1837
+ _debug(' Sensible splitting points:', innermost)
1838
+ for c in sorted(innermost, key=default_sort_key, reverse=True) + [S.Zero]:
1839
+ _debug(' Trying to split at', c)
1840
+ if not c.is_extended_real:
1841
+ _debug(' Non-real splitting point.')
1842
+ continue
1843
+ res1 = _meijerint_definite_2(f.subs(x, x + c), x)
1844
+ if res1 is None:
1845
+ _debug(' But could not compute first integral.')
1846
+ continue
1847
+ res2 = _meijerint_definite_2(f.subs(x, c - x), x)
1848
+ if res2 is None:
1849
+ _debug(' But could not compute second integral.')
1850
+ continue
1851
+ res1, cond1 = res1
1852
+ res2, cond2 = res2
1853
+ cond = _condsimp(And(cond1, cond2))
1854
+ if cond == False:
1855
+ _debug(' But combined condition is always false.')
1856
+ continue
1857
+ res = res1 + res2
1858
+ return res, cond
1859
+
1860
+ elif a is S.Infinity:
1861
+ res = meijerint_definite(f, x, b, S.Infinity)
1862
+ return -res[0], res[1]
1863
+
1864
+ elif (a, b) == (S.Zero, S.Infinity):
1865
+ # This is a common case - try it directly first.
1866
+ res = _meijerint_definite_2(f, x)
1867
+ if res:
1868
+ if _has(res[0], meijerg):
1869
+ results.append(res)
1870
+ else:
1871
+ return res
1872
+
1873
+ else:
1874
+ if b is S.Infinity:
1875
+ for split in _find_splitting_points(f, x):
1876
+ if (a - split >= 0) == True:
1877
+ _debugf('Trying x -> x + %s', split)
1878
+ res = _meijerint_definite_2(f.subs(x, x + split)
1879
+ *Heaviside(x + split - a), x)
1880
+ if res:
1881
+ if _has(res[0], meijerg):
1882
+ results.append(res)
1883
+ else:
1884
+ return res
1885
+
1886
+ f = f.subs(x, x + a)
1887
+ b = b - a
1888
+ a = 0
1889
+ if b is not S.Infinity:
1890
+ phi = exp(S.ImaginaryUnit*arg(b))
1891
+ b = Abs(b)
1892
+ f = f.subs(x, phi*x)
1893
+ f *= Heaviside(b - x)*phi
1894
+ b = S.Infinity
1895
+
1896
+ _debug('Changed limits to', a, b)
1897
+ _debug('Changed function to', f)
1898
+ res = _meijerint_definite_2(f, x)
1899
+ if res:
1900
+ if _has(res[0], meijerg):
1901
+ results.append(res)
1902
+ else:
1903
+ return res
1904
+ if f_.has(HyperbolicFunction):
1905
+ _debug('Try rewriting hyperbolics in terms of exp.')
1906
+ rv = meijerint_definite(
1907
+ _rewrite_hyperbolics_as_exp(f_), x_, a_, b_)
1908
+ if rv:
1909
+ if not isinstance(rv, list):
1910
+ from sympy.simplify.radsimp import collect
1911
+ rv = (collect(factor_terms(rv[0]), rv[0].atoms(exp)),) + rv[1:]
1912
+ return rv
1913
+ results.extend(rv)
1914
+ if results:
1915
+ return next(ordered(results))
1916
+
1917
+
1918
+ def _guess_expansion(f, x):
1919
+ """ Try to guess sensible rewritings for integrand f(x). """
1920
+ res = [(f, 'original integrand')]
1921
+
1922
+ orig = res[-1][0]
1923
+ saw = {orig}
1924
+ expanded = expand_mul(orig)
1925
+ if expanded not in saw:
1926
+ res += [(expanded, 'expand_mul')]
1927
+ saw.add(expanded)
1928
+
1929
+ expanded = expand(orig)
1930
+ if expanded not in saw:
1931
+ res += [(expanded, 'expand')]
1932
+ saw.add(expanded)
1933
+
1934
+ if orig.has(TrigonometricFunction, HyperbolicFunction):
1935
+ expanded = expand_mul(expand_trig(orig))
1936
+ if expanded not in saw:
1937
+ res += [(expanded, 'expand_trig, expand_mul')]
1938
+ saw.add(expanded)
1939
+
1940
+ if orig.has(cos, sin):
1941
+ from sympy.simplify.fu import sincos_to_sum
1942
+ reduced = sincos_to_sum(orig)
1943
+ if reduced not in saw:
1944
+ res += [(reduced, 'trig power reduction')]
1945
+ saw.add(reduced)
1946
+
1947
+ return res
1948
+
1949
+
1950
+ def _meijerint_definite_2(f, x):
1951
+ """
1952
+ Try to integrate f dx from zero to infinity.
1953
+
1954
+ The body of this function computes various 'simplifications'
1955
+ f1, f2, ... of f (e.g. by calling expand_mul(), trigexpand()
1956
+ - see _guess_expansion) and calls _meijerint_definite_3 with each of
1957
+ these in succession.
1958
+ If _meijerint_definite_3 succeeds with any of the simplified functions,
1959
+ returns this result.
1960
+ """
1961
+ # This function does preparation for (2), calls
1962
+ # _meijerint_definite_3 for (2) and (3) combined.
1963
+
1964
+ # use a positive dummy - we integrate from 0 to oo
1965
+ # XXX if a nonnegative symbol is used there will be test failures
1966
+ dummy = _dummy('x', 'meijerint-definite2', f, positive=True)
1967
+ f = f.subs(x, dummy)
1968
+ x = dummy
1969
+
1970
+ if f == 0:
1971
+ return S.Zero, True
1972
+
1973
+ for g, explanation in _guess_expansion(f, x):
1974
+ _debug('Trying', explanation)
1975
+ res = _meijerint_definite_3(g, x)
1976
+ if res:
1977
+ return res
1978
+
1979
+
1980
+ def _meijerint_definite_3(f, x):
1981
+ """
1982
+ Try to integrate f dx from zero to infinity.
1983
+
1984
+ This function calls _meijerint_definite_4 to try to compute the
1985
+ integral. If this fails, it tries using linearity.
1986
+ """
1987
+ res = _meijerint_definite_4(f, x)
1988
+ if res and res[1] != False:
1989
+ return res
1990
+ if f.is_Add:
1991
+ _debug('Expanding and evaluating all terms.')
1992
+ ress = [_meijerint_definite_4(g, x) for g in f.args]
1993
+ if all(r is not None for r in ress):
1994
+ conds = []
1995
+ res = S.Zero
1996
+ for r, c in ress:
1997
+ res += r
1998
+ conds += [c]
1999
+ c = And(*conds)
2000
+ if c != False:
2001
+ return res, c
2002
+
2003
+
2004
+ def _my_unpolarify(f):
2005
+ return _eval_cond(unpolarify(f))
2006
+
2007
+
2008
+ @timeit
2009
+ def _meijerint_definite_4(f, x, only_double=False):
2010
+ """
2011
+ Try to integrate f dx from zero to infinity.
2012
+
2013
+ Explanation
2014
+ ===========
2015
+
2016
+ This function tries to apply the integration theorems found in literature,
2017
+ i.e. it tries to rewrite f as either one or a product of two G-functions.
2018
+
2019
+ The parameter ``only_double`` is used internally in the recursive algorithm
2020
+ to disable trying to rewrite f as a single G-function.
2021
+ """
2022
+ from sympy.simplify import hyperexpand
2023
+ # This function does (2) and (3)
2024
+ _debug('Integrating', f)
2025
+ # Try single G function.
2026
+ if not only_double:
2027
+ gs = _rewrite1(f, x, recursive=False)
2028
+ if gs is not None:
2029
+ fac, po, g, cond = gs
2030
+ _debug('Could rewrite as single G function:', fac, po, g)
2031
+ res = S.Zero
2032
+ for C, s, f in g:
2033
+ if C == 0:
2034
+ continue
2035
+ C, f = _rewrite_saxena_1(fac*C, po*x**s, f, x)
2036
+ res += C*_int0oo_1(f, x)
2037
+ cond = And(cond, _check_antecedents_1(f, x))
2038
+ if cond == False:
2039
+ break
2040
+ cond = _my_unpolarify(cond)
2041
+ if cond == False:
2042
+ _debug('But cond is always False.')
2043
+ else:
2044
+ _debug('Result before branch substitutions is:', res)
2045
+ return _my_unpolarify(hyperexpand(res)), cond
2046
+
2047
+ # Try two G functions.
2048
+ gs = _rewrite2(f, x)
2049
+ if gs is not None:
2050
+ for full_pb in [False, True]:
2051
+ fac, po, g1, g2, cond = gs
2052
+ _debug('Could rewrite as two G functions:', fac, po, g1, g2)
2053
+ res = S.Zero
2054
+ for C1, s1, f1 in g1:
2055
+ for C2, s2, f2 in g2:
2056
+ r = _rewrite_saxena(fac*C1*C2, po*x**(s1 + s2),
2057
+ f1, f2, x, full_pb)
2058
+ if r is None:
2059
+ _debug('Non-rational exponents.')
2060
+ return
2061
+ C, f1_, f2_ = r
2062
+ _debug('Saxena subst for yielded:', C, f1_, f2_)
2063
+ cond = And(cond, _check_antecedents(f1_, f2_, x))
2064
+ if cond == False:
2065
+ break
2066
+ res += C*_int0oo(f1_, f2_, x)
2067
+ else:
2068
+ continue
2069
+ break
2070
+ cond = _my_unpolarify(cond)
2071
+ if cond == False:
2072
+ _debugf('But cond is always False (full_pb=%s).', full_pb)
2073
+ else:
2074
+ _debugf('Result before branch substitutions is: %s', (res, ))
2075
+ if only_double:
2076
+ return res, cond
2077
+ return _my_unpolarify(hyperexpand(res)), cond
2078
+
2079
+
2080
+ def meijerint_inversion(f, x, t):
2081
+ r"""
2082
+ Compute the inverse laplace transform
2083
+ $\int_{c+i\infty}^{c-i\infty} f(x) e^{tx}\, dx$,
2084
+ for real c larger than the real part of all singularities of ``f``.
2085
+
2086
+ Note that ``t`` is always assumed real and positive.
2087
+
2088
+ Return None if the integral does not exist or could not be evaluated.
2089
+
2090
+ Examples
2091
+ ========
2092
+
2093
+ >>> from sympy.abc import x, t
2094
+ >>> from sympy.integrals.meijerint import meijerint_inversion
2095
+ >>> meijerint_inversion(1/x, x, t)
2096
+ Heaviside(t)
2097
+ """
2098
+ f_ = f
2099
+ t_ = t
2100
+ t = Dummy('t', polar=True) # We don't want sqrt(t**2) = abs(t) etc
2101
+ f = f.subs(t_, t)
2102
+ _debug('Laplace-inverting', f)
2103
+ if not _is_analytic(f, x):
2104
+ _debug('But expression is not analytic.')
2105
+ return None
2106
+ # Exponentials correspond to shifts; we filter them out and then
2107
+ # shift the result later. If we are given an Add this will not
2108
+ # work, but the calling code will take care of that.
2109
+ shift = S.Zero
2110
+
2111
+ if f.is_Mul:
2112
+ args = list(f.args)
2113
+ elif isinstance(f, exp):
2114
+ args = [f]
2115
+ else:
2116
+ args = None
2117
+
2118
+ if args:
2119
+ newargs = []
2120
+ exponentials = []
2121
+ while args:
2122
+ arg = args.pop()
2123
+ if isinstance(arg, exp):
2124
+ arg2 = expand(arg)
2125
+ if arg2.is_Mul:
2126
+ args += arg2.args
2127
+ continue
2128
+ try:
2129
+ a, b = _get_coeff_exp(arg.args[0], x)
2130
+ except _CoeffExpValueError:
2131
+ b = 0
2132
+ if b == 1:
2133
+ exponentials.append(a)
2134
+ else:
2135
+ newargs.append(arg)
2136
+ elif arg.is_Pow:
2137
+ arg2 = expand(arg)
2138
+ if arg2.is_Mul:
2139
+ args += arg2.args
2140
+ continue
2141
+ if x not in arg.base.free_symbols:
2142
+ try:
2143
+ a, b = _get_coeff_exp(arg.exp, x)
2144
+ except _CoeffExpValueError:
2145
+ b = 0
2146
+ if b == 1:
2147
+ exponentials.append(a*log(arg.base))
2148
+ newargs.append(arg)
2149
+ else:
2150
+ newargs.append(arg)
2151
+ shift = Add(*exponentials)
2152
+ f = Mul(*newargs)
2153
+
2154
+ if x not in f.free_symbols:
2155
+ _debug('Expression consists of constant and exp shift:', f, shift)
2156
+ cond = Eq(im(shift), 0)
2157
+ if cond == False:
2158
+ _debug('but shift is nonreal, cannot be a Laplace transform')
2159
+ return None
2160
+ res = f*DiracDelta(t + shift)
2161
+ _debug('Result is a delta function, possibly conditional:', res, cond)
2162
+ # cond is True or Eq
2163
+ return Piecewise((res.subs(t, t_), cond))
2164
+
2165
+ gs = _rewrite1(f, x)
2166
+ if gs is not None:
2167
+ fac, po, g, cond = gs
2168
+ _debug('Could rewrite as single G function:', fac, po, g)
2169
+ res = S.Zero
2170
+ for C, s, f in g:
2171
+ C, f = _rewrite_inversion(fac*C, po*x**s, f, x)
2172
+ res += C*_int_inversion(f, x, t)
2173
+ cond = And(cond, _check_antecedents_inversion(f, x))
2174
+ if cond == False:
2175
+ break
2176
+ cond = _my_unpolarify(cond)
2177
+ if cond == False:
2178
+ _debug('But cond is always False.')
2179
+ else:
2180
+ _debug('Result before branch substitution:', res)
2181
+ from sympy.simplify import hyperexpand
2182
+ res = _my_unpolarify(hyperexpand(res))
2183
+ if not res.has(Heaviside):
2184
+ res *= Heaviside(t)
2185
+ res = res.subs(t, t + shift)
2186
+ if not isinstance(cond, bool):
2187
+ cond = cond.subs(t, t + shift)
2188
+ from .transforms import InverseLaplaceTransform
2189
+ return Piecewise((res.subs(t, t_), cond),
2190
+ (InverseLaplaceTransform(f_.subs(t, t_), x, t_, None), True))
venv/lib/python3.10/site-packages/sympy/integrals/meijerint_doc.py ADDED
@@ -0,0 +1,37 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """ This module cooks up a docstring when imported. Its only purpose is to
2
+ be displayed in the sphinx documentation. """
3
+
4
+ from __future__ import annotations
5
+ from typing import Any
6
+
7
+ from sympy.integrals.meijerint import _create_lookup_table
8
+ from sympy.core.add import Add
9
+ from sympy.core.basic import Basic
10
+ from sympy.core.relational import Eq
11
+ from sympy.core.symbol import Symbol
12
+ from sympy.printing.latex import latex
13
+
14
+ t: dict[tuple[type[Basic], ...], list[Any]] = {}
15
+ _create_lookup_table(t)
16
+
17
+
18
+ doc = ""
19
+ for about, category in t.items():
20
+ if about == ():
21
+ doc += 'Elementary functions:\n\n'
22
+ else:
23
+ doc += 'Functions involving ' + ', '.join('`%s`' % latex(
24
+ list(category[0][0].atoms(func))[0]) for func in about) + ':\n\n'
25
+ for formula, gs, cond, hint in category:
26
+ if not isinstance(gs, list):
27
+ g = Symbol('\\text{generated}')
28
+ else:
29
+ g = Add(*[fac*f for (fac, f) in gs])
30
+ obj = Eq(formula, g)
31
+ if cond is True:
32
+ cond = ""
33
+ else:
34
+ cond = ',\\text{ if } %s' % latex(cond)
35
+ doc += ".. math::\n %s%s\n\n" % (latex(obj), cond)
36
+
37
+ __doc__ = doc
venv/lib/python3.10/site-packages/sympy/integrals/prde.py ADDED
@@ -0,0 +1,1332 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """
2
+ Algorithms for solving Parametric Risch Differential Equations.
3
+
4
+ The methods used for solving Parametric Risch Differential Equations parallel
5
+ those for solving Risch Differential Equations. See the outline in the
6
+ docstring of rde.py for more information.
7
+
8
+ The Parametric Risch Differential Equation problem is, given f, g1, ..., gm in
9
+ K(t), to determine if there exist y in K(t) and c1, ..., cm in Const(K) such
10
+ that Dy + f*y == Sum(ci*gi, (i, 1, m)), and to find such y and ci if they exist.
11
+
12
+ For the algorithms here G is a list of tuples of factions of the terms on the
13
+ right hand side of the equation (i.e., gi in k(t)), and Q is a list of terms on
14
+ the right hand side of the equation (i.e., qi in k[t]). See the docstring of
15
+ each function for more information.
16
+ """
17
+ import itertools
18
+ from functools import reduce
19
+
20
+ from sympy.core import Dummy, ilcm, Add, Mul, Pow, S
21
+ from sympy.integrals.rde import (order_at, order_at_oo, weak_normalizer,
22
+ bound_degree)
23
+ from sympy.integrals.risch import (gcdex_diophantine, frac_in, derivation,
24
+ residue_reduce, splitfactor, residue_reduce_derivation, DecrementLevel,
25
+ recognize_log_derivative)
26
+ from sympy.polys import Poly, lcm, cancel, sqf_list
27
+ from sympy.polys.polymatrix import PolyMatrix as Matrix
28
+ from sympy.solvers import solve
29
+
30
+ zeros = Matrix.zeros
31
+ eye = Matrix.eye
32
+
33
+
34
+ def prde_normal_denom(fa, fd, G, DE):
35
+ """
36
+ Parametric Risch Differential Equation - Normal part of the denominator.
37
+
38
+ Explanation
39
+ ===========
40
+
41
+ Given a derivation D on k[t] and f, g1, ..., gm in k(t) with f weakly
42
+ normalized with respect to t, return the tuple (a, b, G, h) such that
43
+ a, h in k[t], b in k<t>, G = [g1, ..., gm] in k(t)^m, and for any solution
44
+ c1, ..., cm in Const(k) and y in k(t) of Dy + f*y == Sum(ci*gi, (i, 1, m)),
45
+ q == y*h in k<t> satisfies a*Dq + b*q == Sum(ci*Gi, (i, 1, m)).
46
+ """
47
+ dn, ds = splitfactor(fd, DE)
48
+ Gas, Gds = list(zip(*G))
49
+ gd = reduce(lambda i, j: i.lcm(j), Gds, Poly(1, DE.t))
50
+ en, es = splitfactor(gd, DE)
51
+
52
+ p = dn.gcd(en)
53
+ h = en.gcd(en.diff(DE.t)).quo(p.gcd(p.diff(DE.t)))
54
+
55
+ a = dn*h
56
+ c = a*h
57
+
58
+ ba = a*fa - dn*derivation(h, DE)*fd
59
+ ba, bd = ba.cancel(fd, include=True)
60
+
61
+ G = [(c*A).cancel(D, include=True) for A, D in G]
62
+
63
+ return (a, (ba, bd), G, h)
64
+
65
+ def real_imag(ba, bd, gen):
66
+ """
67
+ Helper function, to get the real and imaginary part of a rational function
68
+ evaluated at sqrt(-1) without actually evaluating it at sqrt(-1).
69
+
70
+ Explanation
71
+ ===========
72
+
73
+ Separates the even and odd power terms by checking the degree of terms wrt
74
+ mod 4. Returns a tuple (ba[0], ba[1], bd) where ba[0] is real part
75
+ of the numerator ba[1] is the imaginary part and bd is the denominator
76
+ of the rational function.
77
+ """
78
+ bd = bd.as_poly(gen).as_dict()
79
+ ba = ba.as_poly(gen).as_dict()
80
+ denom_real = [value if key[0] % 4 == 0 else -value if key[0] % 4 == 2 else 0 for key, value in bd.items()]
81
+ denom_imag = [value if key[0] % 4 == 1 else -value if key[0] % 4 == 3 else 0 for key, value in bd.items()]
82
+ bd_real = sum(r for r in denom_real)
83
+ bd_imag = sum(r for r in denom_imag)
84
+ num_real = [value if key[0] % 4 == 0 else -value if key[0] % 4 == 2 else 0 for key, value in ba.items()]
85
+ num_imag = [value if key[0] % 4 == 1 else -value if key[0] % 4 == 3 else 0 for key, value in ba.items()]
86
+ ba_real = sum(r for r in num_real)
87
+ ba_imag = sum(r for r in num_imag)
88
+ ba = ((ba_real*bd_real + ba_imag*bd_imag).as_poly(gen), (ba_imag*bd_real - ba_real*bd_imag).as_poly(gen))
89
+ bd = (bd_real*bd_real + bd_imag*bd_imag).as_poly(gen)
90
+ return (ba[0], ba[1], bd)
91
+
92
+
93
+ def prde_special_denom(a, ba, bd, G, DE, case='auto'):
94
+ """
95
+ Parametric Risch Differential Equation - Special part of the denominator.
96
+
97
+ Explanation
98
+ ===========
99
+
100
+ Case is one of {'exp', 'tan', 'primitive'} for the hyperexponential,
101
+ hypertangent, and primitive cases, respectively. For the hyperexponential
102
+ (resp. hypertangent) case, given a derivation D on k[t] and a in k[t],
103
+ b in k<t>, and g1, ..., gm in k(t) with Dt/t in k (resp. Dt/(t**2 + 1) in
104
+ k, sqrt(-1) not in k), a != 0, and gcd(a, t) == 1 (resp.
105
+ gcd(a, t**2 + 1) == 1), return the tuple (A, B, GG, h) such that A, B, h in
106
+ k[t], GG = [gg1, ..., ggm] in k(t)^m, and for any solution c1, ..., cm in
107
+ Const(k) and q in k<t> of a*Dq + b*q == Sum(ci*gi, (i, 1, m)), r == q*h in
108
+ k[t] satisfies A*Dr + B*r == Sum(ci*ggi, (i, 1, m)).
109
+
110
+ For case == 'primitive', k<t> == k[t], so it returns (a, b, G, 1) in this
111
+ case.
112
+ """
113
+ # TODO: Merge this with the very similar special_denom() in rde.py
114
+ if case == 'auto':
115
+ case = DE.case
116
+
117
+ if case == 'exp':
118
+ p = Poly(DE.t, DE.t)
119
+ elif case == 'tan':
120
+ p = Poly(DE.t**2 + 1, DE.t)
121
+ elif case in ('primitive', 'base'):
122
+ B = ba.quo(bd)
123
+ return (a, B, G, Poly(1, DE.t))
124
+ else:
125
+ raise ValueError("case must be one of {'exp', 'tan', 'primitive', "
126
+ "'base'}, not %s." % case)
127
+
128
+ nb = order_at(ba, p, DE.t) - order_at(bd, p, DE.t)
129
+ nc = min([order_at(Ga, p, DE.t) - order_at(Gd, p, DE.t) for Ga, Gd in G])
130
+ n = min(0, nc - min(0, nb))
131
+ if not nb:
132
+ # Possible cancellation.
133
+ if case == 'exp':
134
+ dcoeff = DE.d.quo(Poly(DE.t, DE.t))
135
+ with DecrementLevel(DE): # We are guaranteed to not have problems,
136
+ # because case != 'base'.
137
+ alphaa, alphad = frac_in(-ba.eval(0)/bd.eval(0)/a.eval(0), DE.t)
138
+ etaa, etad = frac_in(dcoeff, DE.t)
139
+ A = parametric_log_deriv(alphaa, alphad, etaa, etad, DE)
140
+ if A is not None:
141
+ Q, m, z = A
142
+ if Q == 1:
143
+ n = min(n, m)
144
+
145
+ elif case == 'tan':
146
+ dcoeff = DE.d.quo(Poly(DE.t**2 + 1, DE.t))
147
+ with DecrementLevel(DE): # We are guaranteed to not have problems,
148
+ # because case != 'base'.
149
+ betaa, alphaa, alphad = real_imag(ba, bd*a, DE.t)
150
+ betad = alphad
151
+ etaa, etad = frac_in(dcoeff, DE.t)
152
+ if recognize_log_derivative(Poly(2, DE.t)*betaa, betad, DE):
153
+ A = parametric_log_deriv(alphaa, alphad, etaa, etad, DE)
154
+ B = parametric_log_deriv(betaa, betad, etaa, etad, DE)
155
+ if A is not None and B is not None:
156
+ Q, s, z = A
157
+ # TODO: Add test
158
+ if Q == 1:
159
+ n = min(n, s/2)
160
+
161
+ N = max(0, -nb)
162
+ pN = p**N
163
+ pn = p**-n # This is 1/h
164
+
165
+ A = a*pN
166
+ B = ba*pN.quo(bd) + Poly(n, DE.t)*a*derivation(p, DE).quo(p)*pN
167
+ G = [(Ga*pN*pn).cancel(Gd, include=True) for Ga, Gd in G]
168
+ h = pn
169
+
170
+ # (a*p**N, (b + n*a*Dp/p)*p**N, g1*p**(N - n), ..., gm*p**(N - n), p**-n)
171
+ return (A, B, G, h)
172
+
173
+
174
+ def prde_linear_constraints(a, b, G, DE):
175
+ """
176
+ Parametric Risch Differential Equation - Generate linear constraints on the constants.
177
+
178
+ Explanation
179
+ ===========
180
+
181
+ Given a derivation D on k[t], a, b, in k[t] with gcd(a, b) == 1, and
182
+ G = [g1, ..., gm] in k(t)^m, return Q = [q1, ..., qm] in k[t]^m and a
183
+ matrix M with entries in k(t) such that for any solution c1, ..., cm in
184
+ Const(k) and p in k[t] of a*Dp + b*p == Sum(ci*gi, (i, 1, m)),
185
+ (c1, ..., cm) is a solution of Mx == 0, and p and the ci satisfy
186
+ a*Dp + b*p == Sum(ci*qi, (i, 1, m)).
187
+
188
+ Because M has entries in k(t), and because Matrix does not play well with
189
+ Poly, M will be a Matrix of Basic expressions.
190
+ """
191
+ m = len(G)
192
+
193
+ Gns, Gds = list(zip(*G))
194
+ d = reduce(lambda i, j: i.lcm(j), Gds)
195
+ d = Poly(d, field=True)
196
+ Q = [(ga*(d).quo(gd)).div(d) for ga, gd in G]
197
+
198
+ if not all(ri.is_zero for _, ri in Q):
199
+ N = max(ri.degree(DE.t) for _, ri in Q)
200
+ M = Matrix(N + 1, m, lambda i, j: Q[j][1].nth(i), DE.t)
201
+ else:
202
+ M = Matrix(0, m, [], DE.t) # No constraints, return the empty matrix.
203
+
204
+ qs, _ = list(zip(*Q))
205
+ return (qs, M)
206
+
207
+ def poly_linear_constraints(p, d):
208
+ """
209
+ Given p = [p1, ..., pm] in k[t]^m and d in k[t], return
210
+ q = [q1, ..., qm] in k[t]^m and a matrix M with entries in k such
211
+ that Sum(ci*pi, (i, 1, m)), for c1, ..., cm in k, is divisible
212
+ by d if and only if (c1, ..., cm) is a solution of Mx = 0, in
213
+ which case the quotient is Sum(ci*qi, (i, 1, m)).
214
+ """
215
+ m = len(p)
216
+ q, r = zip(*[pi.div(d) for pi in p])
217
+
218
+ if not all(ri.is_zero for ri in r):
219
+ n = max(ri.degree() for ri in r)
220
+ M = Matrix(n + 1, m, lambda i, j: r[j].nth(i), d.gens)
221
+ else:
222
+ M = Matrix(0, m, [], d.gens) # No constraints.
223
+
224
+ return q, M
225
+
226
+ def constant_system(A, u, DE):
227
+ """
228
+ Generate a system for the constant solutions.
229
+
230
+ Explanation
231
+ ===========
232
+
233
+ Given a differential field (K, D) with constant field C = Const(K), a Matrix
234
+ A, and a vector (Matrix) u with coefficients in K, returns the tuple
235
+ (B, v, s), where B is a Matrix with coefficients in C and v is a vector
236
+ (Matrix) such that either v has coefficients in C, in which case s is True
237
+ and the solutions in C of Ax == u are exactly all the solutions of Bx == v,
238
+ or v has a non-constant coefficient, in which case s is False Ax == u has no
239
+ constant solution.
240
+
241
+ This algorithm is used both in solving parametric problems and in
242
+ determining if an element a of K is a derivative of an element of K or the
243
+ logarithmic derivative of a K-radical using the structure theorem approach.
244
+
245
+ Because Poly does not play well with Matrix yet, this algorithm assumes that
246
+ all matrix entries are Basic expressions.
247
+ """
248
+ if not A:
249
+ return A, u
250
+ Au = A.row_join(u)
251
+ Au, _ = Au.rref()
252
+ # Warning: This will NOT return correct results if cancel() cannot reduce
253
+ # an identically zero expression to 0. The danger is that we might
254
+ # incorrectly prove that an integral is nonelementary (such as
255
+ # risch_integrate(exp((sin(x)**2 + cos(x)**2 - 1)*x**2), x).
256
+ # But this is a limitation in computer algebra in general, and implicit
257
+ # in the correctness of the Risch Algorithm is the computability of the
258
+ # constant field (actually, this same correctness problem exists in any
259
+ # algorithm that uses rref()).
260
+ #
261
+ # We therefore limit ourselves to constant fields that are computable
262
+ # via the cancel() function, in order to prevent a speed bottleneck from
263
+ # calling some more complex simplification function (rational function
264
+ # coefficients will fall into this class). Furthermore, (I believe) this
265
+ # problem will only crop up if the integral explicitly contains an
266
+ # expression in the constant field that is identically zero, but cannot
267
+ # be reduced to such by cancel(). Therefore, a careful user can avoid this
268
+ # problem entirely by being careful with the sorts of expressions that
269
+ # appear in his integrand in the variables other than the integration
270
+ # variable (the structure theorems should be able to completely decide these
271
+ # problems in the integration variable).
272
+
273
+ A, u = Au[:, :-1], Au[:, -1]
274
+
275
+ D = lambda x: derivation(x, DE, basic=True)
276
+
277
+ for j, i in itertools.product(range(A.cols), range(A.rows)):
278
+ if A[i, j].expr.has(*DE.T):
279
+ # This assumes that const(F(t0, ..., tn) == const(K) == F
280
+ Ri = A[i, :]
281
+ # Rm+1; m = A.rows
282
+ DAij = D(A[i, j])
283
+ Rm1 = Ri.applyfunc(lambda x: D(x) / DAij)
284
+ um1 = D(u[i]) / DAij
285
+
286
+ Aj = A[:, j]
287
+ A = A - Aj * Rm1
288
+ u = u - Aj * um1
289
+
290
+ A = A.col_join(Rm1)
291
+ u = u.col_join(Matrix([um1], u.gens))
292
+
293
+ return (A, u)
294
+
295
+
296
+ def prde_spde(a, b, Q, n, DE):
297
+ """
298
+ Special Polynomial Differential Equation algorithm: Parametric Version.
299
+
300
+ Explanation
301
+ ===========
302
+
303
+ Given a derivation D on k[t], an integer n, and a, b, q1, ..., qm in k[t]
304
+ with deg(a) > 0 and gcd(a, b) == 1, return (A, B, Q, R, n1), with
305
+ Qq = [q1, ..., qm] and R = [r1, ..., rm], such that for any solution
306
+ c1, ..., cm in Const(k) and q in k[t] of degree at most n of
307
+ a*Dq + b*q == Sum(ci*gi, (i, 1, m)), p = (q - Sum(ci*ri, (i, 1, m)))/a has
308
+ degree at most n1 and satisfies A*Dp + B*p == Sum(ci*qi, (i, 1, m))
309
+ """
310
+ R, Z = list(zip(*[gcdex_diophantine(b, a, qi) for qi in Q]))
311
+
312
+ A = a
313
+ B = b + derivation(a, DE)
314
+ Qq = [zi - derivation(ri, DE) for ri, zi in zip(R, Z)]
315
+ R = list(R)
316
+ n1 = n - a.degree(DE.t)
317
+
318
+ return (A, B, Qq, R, n1)
319
+
320
+
321
+ def prde_no_cancel_b_large(b, Q, n, DE):
322
+ """
323
+ Parametric Poly Risch Differential Equation - No cancellation: deg(b) large enough.
324
+
325
+ Explanation
326
+ ===========
327
+
328
+ Given a derivation D on k[t], n in ZZ, and b, q1, ..., qm in k[t] with
329
+ b != 0 and either D == d/dt or deg(b) > max(0, deg(D) - 1), returns
330
+ h1, ..., hr in k[t] and a matrix A with coefficients in Const(k) such that
331
+ if c1, ..., cm in Const(k) and q in k[t] satisfy deg(q) <= n and
332
+ Dq + b*q == Sum(ci*qi, (i, 1, m)), then q = Sum(dj*hj, (j, 1, r)), where
333
+ d1, ..., dr in Const(k) and A*Matrix([[c1, ..., cm, d1, ..., dr]]).T == 0.
334
+ """
335
+ db = b.degree(DE.t)
336
+ m = len(Q)
337
+ H = [Poly(0, DE.t)]*m
338
+
339
+ for N, i in itertools.product(range(n, -1, -1), range(m)): # [n, ..., 0]
340
+ si = Q[i].nth(N + db)/b.LC()
341
+ sitn = Poly(si*DE.t**N, DE.t)
342
+ H[i] = H[i] + sitn
343
+ Q[i] = Q[i] - derivation(sitn, DE) - b*sitn
344
+
345
+ if all(qi.is_zero for qi in Q):
346
+ dc = -1
347
+ else:
348
+ dc = max([qi.degree(DE.t) for qi in Q])
349
+ M = Matrix(dc + 1, m, lambda i, j: Q[j].nth(i), DE.t)
350
+ A, u = constant_system(M, zeros(dc + 1, 1, DE.t), DE)
351
+ c = eye(m, DE.t)
352
+ A = A.row_join(zeros(A.rows, m, DE.t)).col_join(c.row_join(-c))
353
+
354
+ return (H, A)
355
+
356
+
357
+ def prde_no_cancel_b_small(b, Q, n, DE):
358
+ """
359
+ Parametric Poly Risch Differential Equation - No cancellation: deg(b) small enough.
360
+
361
+ Explanation
362
+ ===========
363
+
364
+ Given a derivation D on k[t], n in ZZ, and b, q1, ..., qm in k[t] with
365
+ deg(b) < deg(D) - 1 and either D == d/dt or deg(D) >= 2, returns
366
+ h1, ..., hr in k[t] and a matrix A with coefficients in Const(k) such that
367
+ if c1, ..., cm in Const(k) and q in k[t] satisfy deg(q) <= n and
368
+ Dq + b*q == Sum(ci*qi, (i, 1, m)) then q = Sum(dj*hj, (j, 1, r)) where
369
+ d1, ..., dr in Const(k) and A*Matrix([[c1, ..., cm, d1, ..., dr]]).T == 0.
370
+ """
371
+ m = len(Q)
372
+ H = [Poly(0, DE.t)]*m
373
+
374
+ for N, i in itertools.product(range(n, 0, -1), range(m)): # [n, ..., 1]
375
+ si = Q[i].nth(N + DE.d.degree(DE.t) - 1)/(N*DE.d.LC())
376
+ sitn = Poly(si*DE.t**N, DE.t)
377
+ H[i] = H[i] + sitn
378
+ Q[i] = Q[i] - derivation(sitn, DE) - b*sitn
379
+
380
+ if b.degree(DE.t) > 0:
381
+ for i in range(m):
382
+ si = Poly(Q[i].nth(b.degree(DE.t))/b.LC(), DE.t)
383
+ H[i] = H[i] + si
384
+ Q[i] = Q[i] - derivation(si, DE) - b*si
385
+ if all(qi.is_zero for qi in Q):
386
+ dc = -1
387
+ else:
388
+ dc = max([qi.degree(DE.t) for qi in Q])
389
+ M = Matrix(dc + 1, m, lambda i, j: Q[j].nth(i), DE.t)
390
+ A, u = constant_system(M, zeros(dc + 1, 1, DE.t), DE)
391
+ c = eye(m, DE.t)
392
+ A = A.row_join(zeros(A.rows, m, DE.t)).col_join(c.row_join(-c))
393
+ return (H, A)
394
+
395
+ # else: b is in k, deg(qi) < deg(Dt)
396
+
397
+ t = DE.t
398
+ if DE.case != 'base':
399
+ with DecrementLevel(DE):
400
+ t0 = DE.t # k = k0(t0)
401
+ ba, bd = frac_in(b, t0, field=True)
402
+ Q0 = [frac_in(qi.TC(), t0, field=True) for qi in Q]
403
+ f, B = param_rischDE(ba, bd, Q0, DE)
404
+
405
+ # f = [f1, ..., fr] in k^r and B is a matrix with
406
+ # m + r columns and entries in Const(k) = Const(k0)
407
+ # such that Dy0 + b*y0 = Sum(ci*qi, (i, 1, m)) has
408
+ # a solution y0 in k with c1, ..., cm in Const(k)
409
+ # if and only y0 = Sum(dj*fj, (j, 1, r)) where
410
+ # d1, ..., dr ar in Const(k) and
411
+ # B*Matrix([c1, ..., cm, d1, ..., dr]) == 0.
412
+
413
+ # Transform fractions (fa, fd) in f into constant
414
+ # polynomials fa/fd in k[t].
415
+ # (Is there a better way?)
416
+ f = [Poly(fa.as_expr()/fd.as_expr(), t, field=True)
417
+ for fa, fd in f]
418
+ B = Matrix.from_Matrix(B.to_Matrix(), t)
419
+ else:
420
+ # Base case. Dy == 0 for all y in k and b == 0.
421
+ # Dy + b*y = Sum(ci*qi) is solvable if and only if
422
+ # Sum(ci*qi) == 0 in which case the solutions are
423
+ # y = d1*f1 for f1 = 1 and any d1 in Const(k) = k.
424
+
425
+ f = [Poly(1, t, field=True)] # r = 1
426
+ B = Matrix([[qi.TC() for qi in Q] + [S.Zero]], DE.t)
427
+ # The condition for solvability is
428
+ # B*Matrix([c1, ..., cm, d1]) == 0
429
+ # There are no constraints on d1.
430
+
431
+ # Coefficients of t^j (j > 0) in Sum(ci*qi) must be zero.
432
+ d = max([qi.degree(DE.t) for qi in Q])
433
+ if d > 0:
434
+ M = Matrix(d, m, lambda i, j: Q[j].nth(i + 1), DE.t)
435
+ A, _ = constant_system(M, zeros(d, 1, DE.t), DE)
436
+ else:
437
+ # No constraints on the hj.
438
+ A = Matrix(0, m, [], DE.t)
439
+
440
+ # Solutions of the original equation are
441
+ # y = Sum(dj*fj, (j, 1, r) + Sum(ei*hi, (i, 1, m)),
442
+ # where ei == ci (i = 1, ..., m), when
443
+ # A*Matrix([c1, ..., cm]) == 0 and
444
+ # B*Matrix([c1, ..., cm, d1, ..., dr]) == 0
445
+
446
+ # Build combined constraint matrix with m + r + m columns.
447
+
448
+ r = len(f)
449
+ I = eye(m, DE.t)
450
+ A = A.row_join(zeros(A.rows, r + m, DE.t))
451
+ B = B.row_join(zeros(B.rows, m, DE.t))
452
+ C = I.row_join(zeros(m, r, DE.t)).row_join(-I)
453
+
454
+ return f + H, A.col_join(B).col_join(C)
455
+
456
+
457
+ def prde_cancel_liouvillian(b, Q, n, DE):
458
+ """
459
+ Pg, 237.
460
+ """
461
+ H = []
462
+
463
+ # Why use DecrementLevel? Below line answers that:
464
+ # Assuming that we can solve such problems over 'k' (not k[t])
465
+ if DE.case == 'primitive':
466
+ with DecrementLevel(DE):
467
+ ba, bd = frac_in(b, DE.t, field=True)
468
+
469
+ for i in range(n, -1, -1):
470
+ if DE.case == 'exp': # this re-checking can be avoided
471
+ with DecrementLevel(DE):
472
+ ba, bd = frac_in(b + (i*(derivation(DE.t, DE)/DE.t)).as_poly(b.gens),
473
+ DE.t, field=True)
474
+ with DecrementLevel(DE):
475
+ Qy = [frac_in(q.nth(i), DE.t, field=True) for q in Q]
476
+ fi, Ai = param_rischDE(ba, bd, Qy, DE)
477
+ fi = [Poly(fa.as_expr()/fd.as_expr(), DE.t, field=True)
478
+ for fa, fd in fi]
479
+ Ai = Ai.set_gens(DE.t)
480
+
481
+ ri = len(fi)
482
+
483
+ if i == n:
484
+ M = Ai
485
+ else:
486
+ M = Ai.col_join(M.row_join(zeros(M.rows, ri, DE.t)))
487
+
488
+ Fi, hi = [None]*ri, [None]*ri
489
+
490
+ # from eq. on top of p.238 (unnumbered)
491
+ for j in range(ri):
492
+ hji = fi[j] * (DE.t**i).as_poly(fi[j].gens)
493
+ hi[j] = hji
494
+ # building up Sum(djn*(D(fjn*t^n) - b*fjnt^n))
495
+ Fi[j] = -(derivation(hji, DE) - b*hji)
496
+
497
+ H += hi
498
+ # in the next loop instead of Q it has
499
+ # to be Q + Fi taking its place
500
+ Q = Q + Fi
501
+
502
+ return (H, M)
503
+
504
+
505
+ def param_poly_rischDE(a, b, q, n, DE):
506
+ """Polynomial solutions of a parametric Risch differential equation.
507
+
508
+ Explanation
509
+ ===========
510
+
511
+ Given a derivation D in k[t], a, b in k[t] relatively prime, and q
512
+ = [q1, ..., qm] in k[t]^m, return h = [h1, ..., hr] in k[t]^r and
513
+ a matrix A with m + r columns and entries in Const(k) such that
514
+ a*Dp + b*p = Sum(ci*qi, (i, 1, m)) has a solution p of degree <= n
515
+ in k[t] with c1, ..., cm in Const(k) if and only if p = Sum(dj*hj,
516
+ (j, 1, r)) where d1, ..., dr are in Const(k) and (c1, ..., cm,
517
+ d1, ..., dr) is a solution of Ax == 0.
518
+ """
519
+ m = len(q)
520
+ if n < 0:
521
+ # Only the trivial zero solution is possible.
522
+ # Find relations between the qi.
523
+ if all(qi.is_zero for qi in q):
524
+ return [], zeros(1, m, DE.t) # No constraints.
525
+
526
+ N = max([qi.degree(DE.t) for qi in q])
527
+ M = Matrix(N + 1, m, lambda i, j: q[j].nth(i), DE.t)
528
+ A, _ = constant_system(M, zeros(M.rows, 1, DE.t), DE)
529
+
530
+ return [], A
531
+
532
+ if a.is_ground:
533
+ # Normalization: a = 1.
534
+ a = a.LC()
535
+ b, q = b.quo_ground(a), [qi.quo_ground(a) for qi in q]
536
+
537
+ if not b.is_zero and (DE.case == 'base' or
538
+ b.degree() > max(0, DE.d.degree() - 1)):
539
+ return prde_no_cancel_b_large(b, q, n, DE)
540
+
541
+ elif ((b.is_zero or b.degree() < DE.d.degree() - 1)
542
+ and (DE.case == 'base' or DE.d.degree() >= 2)):
543
+ return prde_no_cancel_b_small(b, q, n, DE)
544
+
545
+ elif (DE.d.degree() >= 2 and
546
+ b.degree() == DE.d.degree() - 1 and
547
+ n > -b.as_poly().LC()/DE.d.as_poly().LC()):
548
+ raise NotImplementedError("prde_no_cancel_b_equal() is "
549
+ "not yet implemented.")
550
+
551
+ else:
552
+ # Liouvillian cases
553
+ if DE.case in ('primitive', 'exp'):
554
+ return prde_cancel_liouvillian(b, q, n, DE)
555
+ else:
556
+ raise NotImplementedError("non-linear and hypertangent "
557
+ "cases have not yet been implemented")
558
+
559
+ # else: deg(a) > 0
560
+
561
+ # Iterate SPDE as long as possible cumulating coefficient
562
+ # and terms for the recovery of original solutions.
563
+ alpha, beta = a.one, [a.zero]*m
564
+ while n >= 0: # and a, b relatively prime
565
+ a, b, q, r, n = prde_spde(a, b, q, n, DE)
566
+ beta = [betai + alpha*ri for betai, ri in zip(beta, r)]
567
+ alpha *= a
568
+ # Solutions p of a*Dp + b*p = Sum(ci*qi) correspond to
569
+ # solutions alpha*p + Sum(ci*betai) of the initial equation.
570
+ d = a.gcd(b)
571
+ if not d.is_ground:
572
+ break
573
+
574
+ # a*Dp + b*p = Sum(ci*qi) may have a polynomial solution
575
+ # only if the sum is divisible by d.
576
+
577
+ qq, M = poly_linear_constraints(q, d)
578
+ # qq = [qq1, ..., qqm] where qqi = qi.quo(d).
579
+ # M is a matrix with m columns an entries in k.
580
+ # Sum(fi*qi, (i, 1, m)), where f1, ..., fm are elements of k, is
581
+ # divisible by d if and only if M*Matrix([f1, ..., fm]) == 0,
582
+ # in which case the quotient is Sum(fi*qqi).
583
+
584
+ A, _ = constant_system(M, zeros(M.rows, 1, DE.t), DE)
585
+ # A is a matrix with m columns and entries in Const(k).
586
+ # Sum(ci*qqi) is Sum(ci*qi).quo(d), and the remainder is zero
587
+ # for c1, ..., cm in Const(k) if and only if
588
+ # A*Matrix([c1, ...,cm]) == 0.
589
+
590
+ V = A.nullspace()
591
+ # V = [v1, ..., vu] where each vj is a column matrix with
592
+ # entries aj1, ..., ajm in Const(k).
593
+ # Sum(aji*qi) is divisible by d with exact quotient Sum(aji*qqi).
594
+ # Sum(ci*qi) is divisible by d if and only if ci = Sum(dj*aji)
595
+ # (i = 1, ..., m) for some d1, ..., du in Const(k).
596
+ # In that case, solutions of
597
+ # a*Dp + b*p = Sum(ci*qi) = Sum(dj*Sum(aji*qi))
598
+ # are the same as those of
599
+ # (a/d)*Dp + (b/d)*p = Sum(dj*rj)
600
+ # where rj = Sum(aji*qqi).
601
+
602
+ if not V: # No non-trivial solution.
603
+ return [], eye(m, DE.t) # Could return A, but this has
604
+ # the minimum number of rows.
605
+
606
+ Mqq = Matrix([qq]) # A single row.
607
+ r = [(Mqq*vj)[0] for vj in V] # [r1, ..., ru]
608
+
609
+ # Solutions of (a/d)*Dp + (b/d)*p = Sum(dj*rj) correspond to
610
+ # solutions alpha*p + Sum(Sum(dj*aji)*betai) of the initial
611
+ # equation. These are equal to alpha*p + Sum(dj*fj) where
612
+ # fj = Sum(aji*betai).
613
+ Mbeta = Matrix([beta])
614
+ f = [(Mbeta*vj)[0] for vj in V] # [f1, ..., fu]
615
+
616
+ #
617
+ # Solve the reduced equation recursively.
618
+ #
619
+ g, B = param_poly_rischDE(a.quo(d), b.quo(d), r, n, DE)
620
+
621
+ # g = [g1, ..., gv] in k[t]^v and and B is a matrix with u + v
622
+ # columns and entries in Const(k) such that
623
+ # (a/d)*Dp + (b/d)*p = Sum(dj*rj) has a solution p of degree <= n
624
+ # in k[t] if and only if p = Sum(ek*gk) where e1, ..., ev are in
625
+ # Const(k) and B*Matrix([d1, ..., du, e1, ..., ev]) == 0.
626
+ # The solutions of the original equation are then
627
+ # Sum(dj*fj, (j, 1, u)) + alpha*Sum(ek*gk, (k, 1, v)).
628
+
629
+ # Collect solution components.
630
+ h = f + [alpha*gk for gk in g]
631
+
632
+ # Build combined relation matrix.
633
+ A = -eye(m, DE.t)
634
+ for vj in V:
635
+ A = A.row_join(vj)
636
+ A = A.row_join(zeros(m, len(g), DE.t))
637
+ A = A.col_join(zeros(B.rows, m, DE.t).row_join(B))
638
+
639
+ return h, A
640
+
641
+
642
+ def param_rischDE(fa, fd, G, DE):
643
+ """
644
+ Solve a Parametric Risch Differential Equation: Dy + f*y == Sum(ci*Gi, (i, 1, m)).
645
+
646
+ Explanation
647
+ ===========
648
+
649
+ Given a derivation D in k(t), f in k(t), and G
650
+ = [G1, ..., Gm] in k(t)^m, return h = [h1, ..., hr] in k(t)^r and
651
+ a matrix A with m + r columns and entries in Const(k) such that
652
+ Dy + f*y = Sum(ci*Gi, (i, 1, m)) has a solution y
653
+ in k(t) with c1, ..., cm in Const(k) if and only if y = Sum(dj*hj,
654
+ (j, 1, r)) where d1, ..., dr are in Const(k) and (c1, ..., cm,
655
+ d1, ..., dr) is a solution of Ax == 0.
656
+
657
+ Elements of k(t) are tuples (a, d) with a and d in k[t].
658
+ """
659
+ m = len(G)
660
+ q, (fa, fd) = weak_normalizer(fa, fd, DE)
661
+ # Solutions of the weakly normalized equation Dz + f*z = q*Sum(ci*Gi)
662
+ # correspond to solutions y = z/q of the original equation.
663
+ gamma = q
664
+ G = [(q*ga).cancel(gd, include=True) for ga, gd in G]
665
+
666
+ a, (ba, bd), G, hn = prde_normal_denom(fa, fd, G, DE)
667
+ # Solutions q in k<t> of a*Dq + b*q = Sum(ci*Gi) correspond
668
+ # to solutions z = q/hn of the weakly normalized equation.
669
+ gamma *= hn
670
+
671
+ A, B, G, hs = prde_special_denom(a, ba, bd, G, DE)
672
+ # Solutions p in k[t] of A*Dp + B*p = Sum(ci*Gi) correspond
673
+ # to solutions q = p/hs of the previous equation.
674
+ gamma *= hs
675
+
676
+ g = A.gcd(B)
677
+ a, b, g = A.quo(g), B.quo(g), [gia.cancel(gid*g, include=True) for
678
+ gia, gid in G]
679
+
680
+ # a*Dp + b*p = Sum(ci*gi) may have a polynomial solution
681
+ # only if the sum is in k[t].
682
+
683
+ q, M = prde_linear_constraints(a, b, g, DE)
684
+
685
+ # q = [q1, ..., qm] where qi in k[t] is the polynomial component
686
+ # of the partial fraction expansion of gi.
687
+ # M is a matrix with m columns and entries in k.
688
+ # Sum(fi*gi, (i, 1, m)), where f1, ..., fm are elements of k,
689
+ # is a polynomial if and only if M*Matrix([f1, ..., fm]) == 0,
690
+ # in which case the sum is equal to Sum(fi*qi).
691
+
692
+ M, _ = constant_system(M, zeros(M.rows, 1, DE.t), DE)
693
+ # M is a matrix with m columns and entries in Const(k).
694
+ # Sum(ci*gi) is in k[t] for c1, ..., cm in Const(k)
695
+ # if and only if M*Matrix([c1, ..., cm]) == 0,
696
+ # in which case the sum is Sum(ci*qi).
697
+
698
+ ## Reduce number of constants at this point
699
+
700
+ V = M.nullspace()
701
+ # V = [v1, ..., vu] where each vj is a column matrix with
702
+ # entries aj1, ..., ajm in Const(k).
703
+ # Sum(aji*gi) is in k[t] and equal to Sum(aji*qi) (j = 1, ..., u).
704
+ # Sum(ci*gi) is in k[t] if and only is ci = Sum(dj*aji)
705
+ # (i = 1, ..., m) for some d1, ..., du in Const(k).
706
+ # In that case,
707
+ # Sum(ci*gi) = Sum(ci*qi) = Sum(dj*Sum(aji*qi)) = Sum(dj*rj)
708
+ # where rj = Sum(aji*qi) (j = 1, ..., u) in k[t].
709
+
710
+ if not V: # No non-trivial solution
711
+ return [], eye(m, DE.t)
712
+
713
+ Mq = Matrix([q]) # A single row.
714
+ r = [(Mq*vj)[0] for vj in V] # [r1, ..., ru]
715
+
716
+ # Solutions of a*Dp + b*p = Sum(dj*rj) correspond to solutions
717
+ # y = p/gamma of the initial equation with ci = Sum(dj*aji).
718
+
719
+ try:
720
+ # We try n=5. At least for prde_spde, it will always
721
+ # terminate no matter what n is.
722
+ n = bound_degree(a, b, r, DE, parametric=True)
723
+ except NotImplementedError:
724
+ # A temporary bound is set. Eventually, it will be removed.
725
+ # the currently added test case takes large time
726
+ # even with n=5, and much longer with large n's.
727
+ n = 5
728
+
729
+ h, B = param_poly_rischDE(a, b, r, n, DE)
730
+
731
+ # h = [h1, ..., hv] in k[t]^v and and B is a matrix with u + v
732
+ # columns and entries in Const(k) such that
733
+ # a*Dp + b*p = Sum(dj*rj) has a solution p of degree <= n
734
+ # in k[t] if and only if p = Sum(ek*hk) where e1, ..., ev are in
735
+ # Const(k) and B*Matrix([d1, ..., du, e1, ..., ev]) == 0.
736
+ # The solutions of the original equation for ci = Sum(dj*aji)
737
+ # (i = 1, ..., m) are then y = Sum(ek*hk, (k, 1, v))/gamma.
738
+
739
+ ## Build combined relation matrix with m + u + v columns.
740
+
741
+ A = -eye(m, DE.t)
742
+ for vj in V:
743
+ A = A.row_join(vj)
744
+ A = A.row_join(zeros(m, len(h), DE.t))
745
+ A = A.col_join(zeros(B.rows, m, DE.t).row_join(B))
746
+
747
+ ## Eliminate d1, ..., du.
748
+
749
+ W = A.nullspace()
750
+
751
+ # W = [w1, ..., wt] where each wl is a column matrix with
752
+ # entries blk (k = 1, ..., m + u + v) in Const(k).
753
+ # The vectors (bl1, ..., blm) generate the space of those
754
+ # constant families (c1, ..., cm) for which a solution of
755
+ # the equation Dy + f*y == Sum(ci*Gi) exists. They generate
756
+ # the space and form a basis except possibly when Dy + f*y == 0
757
+ # is solvable in k(t}. The corresponding solutions are
758
+ # y = Sum(blk'*hk, (k, 1, v))/gamma, where k' = k + m + u.
759
+
760
+ v = len(h)
761
+ shape = (len(W), m+v)
762
+ elements = [wl[:m] + wl[-v:] for wl in W] # excise dj's.
763
+ items = [e for row in elements for e in row]
764
+
765
+ # Need to set the shape in case W is empty
766
+ M = Matrix(*shape, items, DE.t)
767
+ N = M.nullspace()
768
+
769
+ # N = [n1, ..., ns] where the ni in Const(k)^(m + v) are column
770
+ # vectors generating the space of linear relations between
771
+ # c1, ..., cm, e1, ..., ev.
772
+
773
+ C = Matrix([ni[:] for ni in N], DE.t) # rows n1, ..., ns.
774
+
775
+ return [hk.cancel(gamma, include=True) for hk in h], C
776
+
777
+
778
+ def limited_integrate_reduce(fa, fd, G, DE):
779
+ """
780
+ Simpler version of step 1 & 2 for the limited integration problem.
781
+
782
+ Explanation
783
+ ===========
784
+
785
+ Given a derivation D on k(t) and f, g1, ..., gn in k(t), return
786
+ (a, b, h, N, g, V) such that a, b, h in k[t], N is a non-negative integer,
787
+ g in k(t), V == [v1, ..., vm] in k(t)^m, and for any solution v in k(t),
788
+ c1, ..., cm in C of f == Dv + Sum(ci*wi, (i, 1, m)), p = v*h is in k<t>, and
789
+ p and the ci satisfy a*Dp + b*p == g + Sum(ci*vi, (i, 1, m)). Furthermore,
790
+ if S1irr == Sirr, then p is in k[t], and if t is nonlinear or Liouvillian
791
+ over k, then deg(p) <= N.
792
+
793
+ So that the special part is always computed, this function calls the more
794
+ general prde_special_denom() automatically if it cannot determine that
795
+ S1irr == Sirr. Furthermore, it will automatically call bound_degree() when
796
+ t is linear and non-Liouvillian, which for the transcendental case, implies
797
+ that Dt == a*t + b with for some a, b in k*.
798
+ """
799
+ dn, ds = splitfactor(fd, DE)
800
+ E = [splitfactor(gd, DE) for _, gd in G]
801
+ En, Es = list(zip(*E))
802
+ c = reduce(lambda i, j: i.lcm(j), (dn,) + En) # lcm(dn, en1, ..., enm)
803
+ hn = c.gcd(c.diff(DE.t))
804
+ a = hn
805
+ b = -derivation(hn, DE)
806
+ N = 0
807
+
808
+ # These are the cases where we know that S1irr = Sirr, but there could be
809
+ # others, and this algorithm will need to be extended to handle them.
810
+ if DE.case in ('base', 'primitive', 'exp', 'tan'):
811
+ hs = reduce(lambda i, j: i.lcm(j), (ds,) + Es) # lcm(ds, es1, ..., esm)
812
+ a = hn*hs
813
+ b -= (hn*derivation(hs, DE)).quo(hs)
814
+ mu = min(order_at_oo(fa, fd, DE.t), min([order_at_oo(ga, gd, DE.t) for
815
+ ga, gd in G]))
816
+ # So far, all the above are also nonlinear or Liouvillian, but if this
817
+ # changes, then this will need to be updated to call bound_degree()
818
+ # as per the docstring of this function (DE.case == 'other_linear').
819
+ N = hn.degree(DE.t) + hs.degree(DE.t) + max(0, 1 - DE.d.degree(DE.t) - mu)
820
+ else:
821
+ # TODO: implement this
822
+ raise NotImplementedError
823
+
824
+ V = [(-a*hn*ga).cancel(gd, include=True) for ga, gd in G]
825
+ return (a, b, a, N, (a*hn*fa).cancel(fd, include=True), V)
826
+
827
+
828
+ def limited_integrate(fa, fd, G, DE):
829
+ """
830
+ Solves the limited integration problem: f = Dv + Sum(ci*wi, (i, 1, n))
831
+ """
832
+ fa, fd = fa*Poly(1/fd.LC(), DE.t), fd.monic()
833
+ # interpreting limited integration problem as a
834
+ # parametric Risch DE problem
835
+ Fa = Poly(0, DE.t)
836
+ Fd = Poly(1, DE.t)
837
+ G = [(fa, fd)] + G
838
+ h, A = param_rischDE(Fa, Fd, G, DE)
839
+ V = A.nullspace()
840
+ V = [v for v in V if v[0] != 0]
841
+ if not V:
842
+ return None
843
+ else:
844
+ # we can take any vector from V, we take V[0]
845
+ c0 = V[0][0]
846
+ # v = [-1, c1, ..., cm, d1, ..., dr]
847
+ v = V[0]/(-c0)
848
+ r = len(h)
849
+ m = len(v) - r - 1
850
+ C = list(v[1: m + 1])
851
+ y = -sum([v[m + 1 + i]*h[i][0].as_expr()/h[i][1].as_expr() \
852
+ for i in range(r)])
853
+ y_num, y_den = y.as_numer_denom()
854
+ Ya, Yd = Poly(y_num, DE.t), Poly(y_den, DE.t)
855
+ Y = Ya*Poly(1/Yd.LC(), DE.t), Yd.monic()
856
+ return Y, C
857
+
858
+
859
+ def parametric_log_deriv_heu(fa, fd, wa, wd, DE, c1=None):
860
+ """
861
+ Parametric logarithmic derivative heuristic.
862
+
863
+ Explanation
864
+ ===========
865
+
866
+ Given a derivation D on k[t], f in k(t), and a hyperexponential monomial
867
+ theta over k(t), raises either NotImplementedError, in which case the
868
+ heuristic failed, or returns None, in which case it has proven that no
869
+ solution exists, or returns a solution (n, m, v) of the equation
870
+ n*f == Dv/v + m*Dtheta/theta, with v in k(t)* and n, m in ZZ with n != 0.
871
+
872
+ If this heuristic fails, the structure theorem approach will need to be
873
+ used.
874
+
875
+ The argument w == Dtheta/theta
876
+ """
877
+ # TODO: finish writing this and write tests
878
+ c1 = c1 or Dummy('c1')
879
+
880
+ p, a = fa.div(fd)
881
+ q, b = wa.div(wd)
882
+
883
+ B = max(0, derivation(DE.t, DE).degree(DE.t) - 1)
884
+ C = max(p.degree(DE.t), q.degree(DE.t))
885
+
886
+ if q.degree(DE.t) > B:
887
+ eqs = [p.nth(i) - c1*q.nth(i) for i in range(B + 1, C + 1)]
888
+ s = solve(eqs, c1)
889
+ if not s or not s[c1].is_Rational:
890
+ # deg(q) > B, no solution for c.
891
+ return None
892
+
893
+ M, N = s[c1].as_numer_denom()
894
+ M_poly = M.as_poly(q.gens)
895
+ N_poly = N.as_poly(q.gens)
896
+
897
+ nfmwa = N_poly*fa*wd - M_poly*wa*fd
898
+ nfmwd = fd*wd
899
+ Qv = is_log_deriv_k_t_radical_in_field(nfmwa, nfmwd, DE, 'auto')
900
+ if Qv is None:
901
+ # (N*f - M*w) is not the logarithmic derivative of a k(t)-radical.
902
+ return None
903
+
904
+ Q, v = Qv
905
+
906
+ if Q.is_zero or v.is_zero:
907
+ return None
908
+
909
+ return (Q*N, Q*M, v)
910
+
911
+ if p.degree(DE.t) > B:
912
+ return None
913
+
914
+ c = lcm(fd.as_poly(DE.t).LC(), wd.as_poly(DE.t).LC())
915
+ l = fd.monic().lcm(wd.monic())*Poly(c, DE.t)
916
+ ln, ls = splitfactor(l, DE)
917
+ z = ls*ln.gcd(ln.diff(DE.t))
918
+
919
+ if not z.has(DE.t):
920
+ # TODO: We treat this as 'no solution', until the structure
921
+ # theorem version of parametric_log_deriv is implemented.
922
+ return None
923
+
924
+ u1, r1 = (fa*l.quo(fd)).div(z) # (l*f).div(z)
925
+ u2, r2 = (wa*l.quo(wd)).div(z) # (l*w).div(z)
926
+
927
+ eqs = [r1.nth(i) - c1*r2.nth(i) for i in range(z.degree(DE.t))]
928
+ s = solve(eqs, c1)
929
+ if not s or not s[c1].is_Rational:
930
+ # deg(q) <= B, no solution for c.
931
+ return None
932
+
933
+ M, N = s[c1].as_numer_denom()
934
+
935
+ nfmwa = N.as_poly(DE.t)*fa*wd - M.as_poly(DE.t)*wa*fd
936
+ nfmwd = fd*wd
937
+ Qv = is_log_deriv_k_t_radical_in_field(nfmwa, nfmwd, DE)
938
+ if Qv is None:
939
+ # (N*f - M*w) is not the logarithmic derivative of a k(t)-radical.
940
+ return None
941
+
942
+ Q, v = Qv
943
+
944
+ if Q.is_zero or v.is_zero:
945
+ return None
946
+
947
+ return (Q*N, Q*M, v)
948
+
949
+
950
+ def parametric_log_deriv(fa, fd, wa, wd, DE):
951
+ # TODO: Write the full algorithm using the structure theorems.
952
+ # try:
953
+ A = parametric_log_deriv_heu(fa, fd, wa, wd, DE)
954
+ # except NotImplementedError:
955
+ # Heuristic failed, we have to use the full method.
956
+ # TODO: This could be implemented more efficiently.
957
+ # It isn't too worrisome, because the heuristic handles most difficult
958
+ # cases.
959
+ return A
960
+
961
+
962
+ def is_deriv_k(fa, fd, DE):
963
+ r"""
964
+ Checks if Df/f is the derivative of an element of k(t).
965
+
966
+ Explanation
967
+ ===========
968
+
969
+ a in k(t) is the derivative of an element of k(t) if there exists b in k(t)
970
+ such that a = Db. Either returns (ans, u), such that Df/f == Du, or None,
971
+ which means that Df/f is not the derivative of an element of k(t). ans is
972
+ a list of tuples such that Add(*[i*j for i, j in ans]) == u. This is useful
973
+ for seeing exactly which elements of k(t) produce u.
974
+
975
+ This function uses the structure theorem approach, which says that for any
976
+ f in K, Df/f is the derivative of a element of K if and only if there are ri
977
+ in QQ such that::
978
+
979
+ --- --- Dt
980
+ \ r * Dt + \ r * i Df
981
+ / i i / i --- = --.
982
+ --- --- t f
983
+ i in L i in E i
984
+ K/C(x) K/C(x)
985
+
986
+
987
+ Where C = Const(K), L_K/C(x) = { i in {1, ..., n} such that t_i is
988
+ transcendental over C(x)(t_1, ..., t_i-1) and Dt_i = Da_i/a_i, for some a_i
989
+ in C(x)(t_1, ..., t_i-1)* } (i.e., the set of all indices of logarithmic
990
+ monomials of K over C(x)), and E_K/C(x) = { i in {1, ..., n} such that t_i
991
+ is transcendental over C(x)(t_1, ..., t_i-1) and Dt_i/t_i = Da_i, for some
992
+ a_i in C(x)(t_1, ..., t_i-1) } (i.e., the set of all indices of
993
+ hyperexponential monomials of K over C(x)). If K is an elementary extension
994
+ over C(x), then the cardinality of L_K/C(x) U E_K/C(x) is exactly the
995
+ transcendence degree of K over C(x). Furthermore, because Const_D(K) ==
996
+ Const_D(C(x)) == C, deg(Dt_i) == 1 when t_i is in E_K/C(x) and
997
+ deg(Dt_i) == 0 when t_i is in L_K/C(x), implying in particular that E_K/C(x)
998
+ and L_K/C(x) are disjoint.
999
+
1000
+ The sets L_K/C(x) and E_K/C(x) must, by their nature, be computed
1001
+ recursively using this same function. Therefore, it is required to pass
1002
+ them as indices to D (or T). E_args are the arguments of the
1003
+ hyperexponentials indexed by E_K (i.e., if i is in E_K, then T[i] ==
1004
+ exp(E_args[i])). This is needed to compute the final answer u such that
1005
+ Df/f == Du.
1006
+
1007
+ log(f) will be the same as u up to a additive constant. This is because
1008
+ they will both behave the same as monomials. For example, both log(x) and
1009
+ log(2*x) == log(x) + log(2) satisfy Dt == 1/x, because log(2) is constant.
1010
+ Therefore, the term const is returned. const is such that
1011
+ log(const) + f == u. This is calculated by dividing the arguments of one
1012
+ logarithm from the other. Therefore, it is necessary to pass the arguments
1013
+ of the logarithmic terms in L_args.
1014
+
1015
+ To handle the case where we are given Df/f, not f, use is_deriv_k_in_field().
1016
+
1017
+ See also
1018
+ ========
1019
+ is_log_deriv_k_t_radical_in_field, is_log_deriv_k_t_radical
1020
+
1021
+ """
1022
+ # Compute Df/f
1023
+ dfa, dfd = (fd*derivation(fa, DE) - fa*derivation(fd, DE)), fd*fa
1024
+ dfa, dfd = dfa.cancel(dfd, include=True)
1025
+
1026
+ # Our assumption here is that each monomial is recursively transcendental
1027
+ if len(DE.exts) != len(DE.D):
1028
+ if [i for i in DE.cases if i == 'tan'] or \
1029
+ ({i for i in DE.cases if i == 'primitive'} -
1030
+ set(DE.indices('log'))):
1031
+ raise NotImplementedError("Real version of the structure "
1032
+ "theorems with hypertangent support is not yet implemented.")
1033
+
1034
+ # TODO: What should really be done in this case?
1035
+ raise NotImplementedError("Nonelementary extensions not supported "
1036
+ "in the structure theorems.")
1037
+
1038
+ E_part = [DE.D[i].quo(Poly(DE.T[i], DE.T[i])).as_expr() for i in DE.indices('exp')]
1039
+ L_part = [DE.D[i].as_expr() for i in DE.indices('log')]
1040
+
1041
+ # The expression dfa/dfd might not be polynomial in any of its symbols so we
1042
+ # use a Dummy as the generator for PolyMatrix.
1043
+ dum = Dummy()
1044
+ lhs = Matrix([E_part + L_part], dum)
1045
+ rhs = Matrix([dfa.as_expr()/dfd.as_expr()], dum)
1046
+
1047
+ A, u = constant_system(lhs, rhs, DE)
1048
+
1049
+ u = u.to_Matrix() # Poly to Expr
1050
+
1051
+ if not A or not all(derivation(i, DE, basic=True).is_zero for i in u):
1052
+ # If the elements of u are not all constant
1053
+ # Note: See comment in constant_system
1054
+
1055
+ # Also note: derivation(basic=True) calls cancel()
1056
+ return None
1057
+ else:
1058
+ if not all(i.is_Rational for i in u):
1059
+ raise NotImplementedError("Cannot work with non-rational "
1060
+ "coefficients in this case.")
1061
+ else:
1062
+ terms = ([DE.extargs[i] for i in DE.indices('exp')] +
1063
+ [DE.T[i] for i in DE.indices('log')])
1064
+ ans = list(zip(terms, u))
1065
+ result = Add(*[Mul(i, j) for i, j in ans])
1066
+ argterms = ([DE.T[i] for i in DE.indices('exp')] +
1067
+ [DE.extargs[i] for i in DE.indices('log')])
1068
+ l = []
1069
+ ld = []
1070
+ for i, j in zip(argterms, u):
1071
+ # We need to get around things like sqrt(x**2) != x
1072
+ # and also sqrt(x**2 + 2*x + 1) != x + 1
1073
+ # Issue 10798: i need not be a polynomial
1074
+ i, d = i.as_numer_denom()
1075
+ icoeff, iterms = sqf_list(i)
1076
+ l.append(Mul(*([Pow(icoeff, j)] + [Pow(b, e*j) for b, e in iterms])))
1077
+ dcoeff, dterms = sqf_list(d)
1078
+ ld.append(Mul(*([Pow(dcoeff, j)] + [Pow(b, e*j) for b, e in dterms])))
1079
+ const = cancel(fa.as_expr()/fd.as_expr()/Mul(*l)*Mul(*ld))
1080
+
1081
+ return (ans, result, const)
1082
+
1083
+
1084
+ def is_log_deriv_k_t_radical(fa, fd, DE, Df=True):
1085
+ r"""
1086
+ Checks if Df is the logarithmic derivative of a k(t)-radical.
1087
+
1088
+ Explanation
1089
+ ===========
1090
+
1091
+ b in k(t) can be written as the logarithmic derivative of a k(t) radical if
1092
+ there exist n in ZZ and u in k(t) with n, u != 0 such that n*b == Du/u.
1093
+ Either returns (ans, u, n, const) or None, which means that Df cannot be
1094
+ written as the logarithmic derivative of a k(t)-radical. ans is a list of
1095
+ tuples such that Mul(*[i**j for i, j in ans]) == u. This is useful for
1096
+ seeing exactly what elements of k(t) produce u.
1097
+
1098
+ This function uses the structure theorem approach, which says that for any
1099
+ f in K, Df is the logarithmic derivative of a K-radical if and only if there
1100
+ are ri in QQ such that::
1101
+
1102
+ --- --- Dt
1103
+ \ r * Dt + \ r * i
1104
+ / i i / i --- = Df.
1105
+ --- --- t
1106
+ i in L i in E i
1107
+ K/C(x) K/C(x)
1108
+
1109
+
1110
+ Where C = Const(K), L_K/C(x) = { i in {1, ..., n} such that t_i is
1111
+ transcendental over C(x)(t_1, ..., t_i-1) and Dt_i = Da_i/a_i, for some a_i
1112
+ in C(x)(t_1, ..., t_i-1)* } (i.e., the set of all indices of logarithmic
1113
+ monomials of K over C(x)), and E_K/C(x) = { i in {1, ..., n} such that t_i
1114
+ is transcendental over C(x)(t_1, ..., t_i-1) and Dt_i/t_i = Da_i, for some
1115
+ a_i in C(x)(t_1, ..., t_i-1) } (i.e., the set of all indices of
1116
+ hyperexponential monomials of K over C(x)). If K is an elementary extension
1117
+ over C(x), then the cardinality of L_K/C(x) U E_K/C(x) is exactly the
1118
+ transcendence degree of K over C(x). Furthermore, because Const_D(K) ==
1119
+ Const_D(C(x)) == C, deg(Dt_i) == 1 when t_i is in E_K/C(x) and
1120
+ deg(Dt_i) == 0 when t_i is in L_K/C(x), implying in particular that E_K/C(x)
1121
+ and L_K/C(x) are disjoint.
1122
+
1123
+ The sets L_K/C(x) and E_K/C(x) must, by their nature, be computed
1124
+ recursively using this same function. Therefore, it is required to pass
1125
+ them as indices to D (or T). L_args are the arguments of the logarithms
1126
+ indexed by L_K (i.e., if i is in L_K, then T[i] == log(L_args[i])). This is
1127
+ needed to compute the final answer u such that n*f == Du/u.
1128
+
1129
+ exp(f) will be the same as u up to a multiplicative constant. This is
1130
+ because they will both behave the same as monomials. For example, both
1131
+ exp(x) and exp(x + 1) == E*exp(x) satisfy Dt == t. Therefore, the term const
1132
+ is returned. const is such that exp(const)*f == u. This is calculated by
1133
+ subtracting the arguments of one exponential from the other. Therefore, it
1134
+ is necessary to pass the arguments of the exponential terms in E_args.
1135
+
1136
+ To handle the case where we are given Df, not f, use
1137
+ is_log_deriv_k_t_radical_in_field().
1138
+
1139
+ See also
1140
+ ========
1141
+
1142
+ is_log_deriv_k_t_radical_in_field, is_deriv_k
1143
+
1144
+ """
1145
+ if Df:
1146
+ dfa, dfd = (fd*derivation(fa, DE) - fa*derivation(fd, DE)).cancel(fd**2,
1147
+ include=True)
1148
+ else:
1149
+ dfa, dfd = fa, fd
1150
+
1151
+ # Our assumption here is that each monomial is recursively transcendental
1152
+ if len(DE.exts) != len(DE.D):
1153
+ if [i for i in DE.cases if i == 'tan'] or \
1154
+ ({i for i in DE.cases if i == 'primitive'} -
1155
+ set(DE.indices('log'))):
1156
+ raise NotImplementedError("Real version of the structure "
1157
+ "theorems with hypertangent support is not yet implemented.")
1158
+
1159
+ # TODO: What should really be done in this case?
1160
+ raise NotImplementedError("Nonelementary extensions not supported "
1161
+ "in the structure theorems.")
1162
+
1163
+ E_part = [DE.D[i].quo(Poly(DE.T[i], DE.T[i])).as_expr() for i in DE.indices('exp')]
1164
+ L_part = [DE.D[i].as_expr() for i in DE.indices('log')]
1165
+
1166
+ # The expression dfa/dfd might not be polynomial in any of its symbols so we
1167
+ # use a Dummy as the generator for PolyMatrix.
1168
+ dum = Dummy()
1169
+ lhs = Matrix([E_part + L_part], dum)
1170
+ rhs = Matrix([dfa.as_expr()/dfd.as_expr()], dum)
1171
+
1172
+ A, u = constant_system(lhs, rhs, DE)
1173
+
1174
+ u = u.to_Matrix() # Poly to Expr
1175
+
1176
+ if not A or not all(derivation(i, DE, basic=True).is_zero for i in u):
1177
+ # If the elements of u are not all constant
1178
+ # Note: See comment in constant_system
1179
+
1180
+ # Also note: derivation(basic=True) calls cancel()
1181
+ return None
1182
+ else:
1183
+ if not all(i.is_Rational for i in u):
1184
+ # TODO: But maybe we can tell if they're not rational, like
1185
+ # log(2)/log(3). Also, there should be an option to continue
1186
+ # anyway, even if the result might potentially be wrong.
1187
+ raise NotImplementedError("Cannot work with non-rational "
1188
+ "coefficients in this case.")
1189
+ else:
1190
+ n = reduce(ilcm, [i.as_numer_denom()[1] for i in u])
1191
+ u *= n
1192
+ terms = ([DE.T[i] for i in DE.indices('exp')] +
1193
+ [DE.extargs[i] for i in DE.indices('log')])
1194
+ ans = list(zip(terms, u))
1195
+ result = Mul(*[Pow(i, j) for i, j in ans])
1196
+
1197
+ # exp(f) will be the same as result up to a multiplicative
1198
+ # constant. We now find the log of that constant.
1199
+ argterms = ([DE.extargs[i] for i in DE.indices('exp')] +
1200
+ [DE.T[i] for i in DE.indices('log')])
1201
+ const = cancel(fa.as_expr()/fd.as_expr() -
1202
+ Add(*[Mul(i, j/n) for i, j in zip(argterms, u)]))
1203
+
1204
+ return (ans, result, n, const)
1205
+
1206
+
1207
+ def is_log_deriv_k_t_radical_in_field(fa, fd, DE, case='auto', z=None):
1208
+ """
1209
+ Checks if f can be written as the logarithmic derivative of a k(t)-radical.
1210
+
1211
+ Explanation
1212
+ ===========
1213
+
1214
+ It differs from is_log_deriv_k_t_radical(fa, fd, DE, Df=False)
1215
+ for any given fa, fd, DE in that it finds the solution in the
1216
+ given field not in some (possibly unspecified extension) and
1217
+ "in_field" with the function name is used to indicate that.
1218
+
1219
+ f in k(t) can be written as the logarithmic derivative of a k(t) radical if
1220
+ there exist n in ZZ and u in k(t) with n, u != 0 such that n*f == Du/u.
1221
+ Either returns (n, u) or None, which means that f cannot be written as the
1222
+ logarithmic derivative of a k(t)-radical.
1223
+
1224
+ case is one of {'primitive', 'exp', 'tan', 'auto'} for the primitive,
1225
+ hyperexponential, and hypertangent cases, respectively. If case is 'auto',
1226
+ it will attempt to determine the type of the derivation automatically.
1227
+
1228
+ See also
1229
+ ========
1230
+ is_log_deriv_k_t_radical, is_deriv_k
1231
+
1232
+ """
1233
+ fa, fd = fa.cancel(fd, include=True)
1234
+
1235
+ # f must be simple
1236
+ n, s = splitfactor(fd, DE)
1237
+ if not s.is_one:
1238
+ pass
1239
+
1240
+ z = z or Dummy('z')
1241
+ H, b = residue_reduce(fa, fd, DE, z=z)
1242
+ if not b:
1243
+ # I will have to verify, but I believe that the answer should be
1244
+ # None in this case. This should never happen for the
1245
+ # functions given when solving the parametric logarithmic
1246
+ # derivative problem when integration elementary functions (see
1247
+ # Bronstein's book, page 255), so most likely this indicates a bug.
1248
+ return None
1249
+
1250
+ roots = [(i, i.real_roots()) for i, _ in H]
1251
+ if not all(len(j) == i.degree() and all(k.is_Rational for k in j) for
1252
+ i, j in roots):
1253
+ # If f is the logarithmic derivative of a k(t)-radical, then all the
1254
+ # roots of the resultant must be rational numbers.
1255
+ return None
1256
+
1257
+ # [(a, i), ...], where i*log(a) is a term in the log-part of the integral
1258
+ # of f
1259
+ respolys, residues = list(zip(*roots)) or [[], []]
1260
+ # Note: this might be empty, but everything below should work find in that
1261
+ # case (it should be the same as if it were [[1, 1]])
1262
+ residueterms = [(H[j][1].subs(z, i), i) for j in range(len(H)) for
1263
+ i in residues[j]]
1264
+
1265
+ # TODO: finish writing this and write tests
1266
+
1267
+ p = cancel(fa.as_expr()/fd.as_expr() - residue_reduce_derivation(H, DE, z))
1268
+
1269
+ p = p.as_poly(DE.t)
1270
+ if p is None:
1271
+ # f - Dg will be in k[t] if f is the logarithmic derivative of a k(t)-radical
1272
+ return None
1273
+
1274
+ if p.degree(DE.t) >= max(1, DE.d.degree(DE.t)):
1275
+ return None
1276
+
1277
+ if case == 'auto':
1278
+ case = DE.case
1279
+
1280
+ if case == 'exp':
1281
+ wa, wd = derivation(DE.t, DE).cancel(Poly(DE.t, DE.t), include=True)
1282
+ with DecrementLevel(DE):
1283
+ pa, pd = frac_in(p, DE.t, cancel=True)
1284
+ wa, wd = frac_in((wa, wd), DE.t)
1285
+ A = parametric_log_deriv(pa, pd, wa, wd, DE)
1286
+ if A is None:
1287
+ return None
1288
+ n, e, u = A
1289
+ u *= DE.t**e
1290
+
1291
+ elif case == 'primitive':
1292
+ with DecrementLevel(DE):
1293
+ pa, pd = frac_in(p, DE.t)
1294
+ A = is_log_deriv_k_t_radical_in_field(pa, pd, DE, case='auto')
1295
+ if A is None:
1296
+ return None
1297
+ n, u = A
1298
+
1299
+ elif case == 'base':
1300
+ # TODO: we can use more efficient residue reduction from ratint()
1301
+ if not fd.is_sqf or fa.degree() >= fd.degree():
1302
+ # f is the logarithmic derivative in the base case if and only if
1303
+ # f = fa/fd, fd is square-free, deg(fa) < deg(fd), and
1304
+ # gcd(fa, fd) == 1. The last condition is handled by cancel() above.
1305
+ return None
1306
+ # Note: if residueterms = [], returns (1, 1)
1307
+ # f had better be 0 in that case.
1308
+ n = reduce(ilcm, [i.as_numer_denom()[1] for _, i in residueterms], S.One)
1309
+ u = Mul(*[Pow(i, j*n) for i, j in residueterms])
1310
+ return (n, u)
1311
+
1312
+ elif case == 'tan':
1313
+ raise NotImplementedError("The hypertangent case is "
1314
+ "not yet implemented for is_log_deriv_k_t_radical_in_field()")
1315
+
1316
+ elif case in ('other_linear', 'other_nonlinear'):
1317
+ # XXX: If these are supported by the structure theorems, change to NotImplementedError.
1318
+ raise ValueError("The %s case is not supported in this function." % case)
1319
+
1320
+ else:
1321
+ raise ValueError("case must be one of {'primitive', 'exp', 'tan', "
1322
+ "'base', 'auto'}, not %s" % case)
1323
+
1324
+ common_denom = reduce(ilcm, [i.as_numer_denom()[1] for i in [j for _, j in
1325
+ residueterms]] + [n], S.One)
1326
+ residueterms = [(i, j*common_denom) for i, j in residueterms]
1327
+ m = common_denom//n
1328
+ if common_denom != n*m: # Verify exact division
1329
+ raise ValueError("Inexact division")
1330
+ u = cancel(u**m*Mul(*[Pow(i, j) for i, j in residueterms]))
1331
+
1332
+ return (common_denom, u)
venv/lib/python3.10/site-packages/sympy/integrals/quadrature.py ADDED
@@ -0,0 +1,617 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ from sympy.core import S, Dummy, pi
2
+ from sympy.functions.combinatorial.factorials import factorial
3
+ from sympy.functions.elementary.trigonometric import sin, cos
4
+ from sympy.functions.elementary.miscellaneous import sqrt
5
+ from sympy.functions.special.gamma_functions import gamma
6
+ from sympy.polys.orthopolys import (legendre_poly, laguerre_poly,
7
+ hermite_poly, jacobi_poly)
8
+ from sympy.polys.rootoftools import RootOf
9
+
10
+
11
+ def gauss_legendre(n, n_digits):
12
+ r"""
13
+ Computes the Gauss-Legendre quadrature [1]_ points and weights.
14
+
15
+ Explanation
16
+ ===========
17
+
18
+ The Gauss-Legendre quadrature approximates the integral:
19
+
20
+ .. math::
21
+ \int_{-1}^1 f(x)\,dx \approx \sum_{i=1}^n w_i f(x_i)
22
+
23
+ The nodes `x_i` of an order `n` quadrature rule are the roots of `P_n`
24
+ and the weights `w_i` are given by:
25
+
26
+ .. math::
27
+ w_i = \frac{2}{\left(1-x_i^2\right) \left(P'_n(x_i)\right)^2}
28
+
29
+ Parameters
30
+ ==========
31
+
32
+ n :
33
+ The order of quadrature.
34
+ n_digits :
35
+ Number of significant digits of the points and weights to return.
36
+
37
+ Returns
38
+ =======
39
+
40
+ (x, w) : the ``x`` and ``w`` are lists of points and weights as Floats.
41
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
42
+ tuple of lists.
43
+
44
+ Examples
45
+ ========
46
+
47
+ >>> from sympy.integrals.quadrature import gauss_legendre
48
+ >>> x, w = gauss_legendre(3, 5)
49
+ >>> x
50
+ [-0.7746, 0, 0.7746]
51
+ >>> w
52
+ [0.55556, 0.88889, 0.55556]
53
+ >>> x, w = gauss_legendre(4, 5)
54
+ >>> x
55
+ [-0.86114, -0.33998, 0.33998, 0.86114]
56
+ >>> w
57
+ [0.34785, 0.65215, 0.65215, 0.34785]
58
+
59
+ See Also
60
+ ========
61
+
62
+ gauss_laguerre, gauss_gen_laguerre, gauss_hermite, gauss_chebyshev_t, gauss_chebyshev_u, gauss_jacobi, gauss_lobatto
63
+
64
+ References
65
+ ==========
66
+
67
+ .. [1] https://en.wikipedia.org/wiki/Gaussian_quadrature
68
+ .. [2] https://people.sc.fsu.edu/~jburkardt/cpp_src/legendre_rule/legendre_rule.html
69
+ """
70
+ x = Dummy("x")
71
+ p = legendre_poly(n, x, polys=True)
72
+ pd = p.diff(x)
73
+ xi = []
74
+ w = []
75
+ for r in p.real_roots():
76
+ if isinstance(r, RootOf):
77
+ r = r.eval_rational(S.One/10**(n_digits+2))
78
+ xi.append(r.n(n_digits))
79
+ w.append((2/((1-r**2) * pd.subs(x, r)**2)).n(n_digits))
80
+ return xi, w
81
+
82
+
83
+ def gauss_laguerre(n, n_digits):
84
+ r"""
85
+ Computes the Gauss-Laguerre quadrature [1]_ points and weights.
86
+
87
+ Explanation
88
+ ===========
89
+
90
+ The Gauss-Laguerre quadrature approximates the integral:
91
+
92
+ .. math::
93
+ \int_0^{\infty} e^{-x} f(x)\,dx \approx \sum_{i=1}^n w_i f(x_i)
94
+
95
+
96
+ The nodes `x_i` of an order `n` quadrature rule are the roots of `L_n`
97
+ and the weights `w_i` are given by:
98
+
99
+ .. math::
100
+ w_i = \frac{x_i}{(n+1)^2 \left(L_{n+1}(x_i)\right)^2}
101
+
102
+ Parameters
103
+ ==========
104
+
105
+ n :
106
+ The order of quadrature.
107
+ n_digits :
108
+ Number of significant digits of the points and weights to return.
109
+
110
+ Returns
111
+ =======
112
+
113
+ (x, w) : The ``x`` and ``w`` are lists of points and weights as Floats.
114
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
115
+ tuple of lists.
116
+
117
+ Examples
118
+ ========
119
+
120
+ >>> from sympy.integrals.quadrature import gauss_laguerre
121
+ >>> x, w = gauss_laguerre(3, 5)
122
+ >>> x
123
+ [0.41577, 2.2943, 6.2899]
124
+ >>> w
125
+ [0.71109, 0.27852, 0.010389]
126
+ >>> x, w = gauss_laguerre(6, 5)
127
+ >>> x
128
+ [0.22285, 1.1889, 2.9927, 5.7751, 9.8375, 15.983]
129
+ >>> w
130
+ [0.45896, 0.417, 0.11337, 0.010399, 0.00026102, 8.9855e-7]
131
+
132
+ See Also
133
+ ========
134
+
135
+ gauss_legendre, gauss_gen_laguerre, gauss_hermite, gauss_chebyshev_t, gauss_chebyshev_u, gauss_jacobi, gauss_lobatto
136
+
137
+ References
138
+ ==========
139
+
140
+ .. [1] https://en.wikipedia.org/wiki/Gauss%E2%80%93Laguerre_quadrature
141
+ .. [2] https://people.sc.fsu.edu/~jburkardt/cpp_src/laguerre_rule/laguerre_rule.html
142
+ """
143
+ x = Dummy("x")
144
+ p = laguerre_poly(n, x, polys=True)
145
+ p1 = laguerre_poly(n+1, x, polys=True)
146
+ xi = []
147
+ w = []
148
+ for r in p.real_roots():
149
+ if isinstance(r, RootOf):
150
+ r = r.eval_rational(S.One/10**(n_digits+2))
151
+ xi.append(r.n(n_digits))
152
+ w.append((r/((n+1)**2 * p1.subs(x, r)**2)).n(n_digits))
153
+ return xi, w
154
+
155
+
156
+ def gauss_hermite(n, n_digits):
157
+ r"""
158
+ Computes the Gauss-Hermite quadrature [1]_ points and weights.
159
+
160
+ Explanation
161
+ ===========
162
+
163
+ The Gauss-Hermite quadrature approximates the integral:
164
+
165
+ .. math::
166
+ \int_{-\infty}^{\infty} e^{-x^2} f(x)\,dx \approx
167
+ \sum_{i=1}^n w_i f(x_i)
168
+
169
+ The nodes `x_i` of an order `n` quadrature rule are the roots of `H_n`
170
+ and the weights `w_i` are given by:
171
+
172
+ .. math::
173
+ w_i = \frac{2^{n-1} n! \sqrt{\pi}}{n^2 \left(H_{n-1}(x_i)\right)^2}
174
+
175
+ Parameters
176
+ ==========
177
+
178
+ n :
179
+ The order of quadrature.
180
+ n_digits :
181
+ Number of significant digits of the points and weights to return.
182
+
183
+ Returns
184
+ =======
185
+
186
+ (x, w) : The ``x`` and ``w`` are lists of points and weights as Floats.
187
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
188
+ tuple of lists.
189
+
190
+ Examples
191
+ ========
192
+
193
+ >>> from sympy.integrals.quadrature import gauss_hermite
194
+ >>> x, w = gauss_hermite(3, 5)
195
+ >>> x
196
+ [-1.2247, 0, 1.2247]
197
+ >>> w
198
+ [0.29541, 1.1816, 0.29541]
199
+
200
+ >>> x, w = gauss_hermite(6, 5)
201
+ >>> x
202
+ [-2.3506, -1.3358, -0.43608, 0.43608, 1.3358, 2.3506]
203
+ >>> w
204
+ [0.00453, 0.15707, 0.72463, 0.72463, 0.15707, 0.00453]
205
+
206
+ See Also
207
+ ========
208
+
209
+ gauss_legendre, gauss_laguerre, gauss_gen_laguerre, gauss_chebyshev_t, gauss_chebyshev_u, gauss_jacobi, gauss_lobatto
210
+
211
+ References
212
+ ==========
213
+
214
+ .. [1] https://en.wikipedia.org/wiki/Gauss-Hermite_Quadrature
215
+ .. [2] https://people.sc.fsu.edu/~jburkardt/cpp_src/hermite_rule/hermite_rule.html
216
+ .. [3] https://people.sc.fsu.edu/~jburkardt/cpp_src/gen_hermite_rule/gen_hermite_rule.html
217
+ """
218
+ x = Dummy("x")
219
+ p = hermite_poly(n, x, polys=True)
220
+ p1 = hermite_poly(n-1, x, polys=True)
221
+ xi = []
222
+ w = []
223
+ for r in p.real_roots():
224
+ if isinstance(r, RootOf):
225
+ r = r.eval_rational(S.One/10**(n_digits+2))
226
+ xi.append(r.n(n_digits))
227
+ w.append(((2**(n-1) * factorial(n) * sqrt(pi)) /
228
+ (n**2 * p1.subs(x, r)**2)).n(n_digits))
229
+ return xi, w
230
+
231
+
232
+ def gauss_gen_laguerre(n, alpha, n_digits):
233
+ r"""
234
+ Computes the generalized Gauss-Laguerre quadrature [1]_ points and weights.
235
+
236
+ Explanation
237
+ ===========
238
+
239
+ The generalized Gauss-Laguerre quadrature approximates the integral:
240
+
241
+ .. math::
242
+ \int_{0}^\infty x^{\alpha} e^{-x} f(x)\,dx \approx
243
+ \sum_{i=1}^n w_i f(x_i)
244
+
245
+ The nodes `x_i` of an order `n` quadrature rule are the roots of
246
+ `L^{\alpha}_n` and the weights `w_i` are given by:
247
+
248
+ .. math::
249
+ w_i = \frac{\Gamma(\alpha+n)}
250
+ {n \Gamma(n) L^{\alpha}_{n-1}(x_i) L^{\alpha+1}_{n-1}(x_i)}
251
+
252
+ Parameters
253
+ ==========
254
+
255
+ n :
256
+ The order of quadrature.
257
+
258
+ alpha :
259
+ The exponent of the singularity, `\alpha > -1`.
260
+
261
+ n_digits :
262
+ Number of significant digits of the points and weights to return.
263
+
264
+ Returns
265
+ =======
266
+
267
+ (x, w) : the ``x`` and ``w`` are lists of points and weights as Floats.
268
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
269
+ tuple of lists.
270
+
271
+ Examples
272
+ ========
273
+
274
+ >>> from sympy import S
275
+ >>> from sympy.integrals.quadrature import gauss_gen_laguerre
276
+ >>> x, w = gauss_gen_laguerre(3, -S.Half, 5)
277
+ >>> x
278
+ [0.19016, 1.7845, 5.5253]
279
+ >>> w
280
+ [1.4493, 0.31413, 0.00906]
281
+
282
+ >>> x, w = gauss_gen_laguerre(4, 3*S.Half, 5)
283
+ >>> x
284
+ [0.97851, 2.9904, 6.3193, 11.712]
285
+ >>> w
286
+ [0.53087, 0.67721, 0.11895, 0.0023152]
287
+
288
+ See Also
289
+ ========
290
+
291
+ gauss_legendre, gauss_laguerre, gauss_hermite, gauss_chebyshev_t, gauss_chebyshev_u, gauss_jacobi, gauss_lobatto
292
+
293
+ References
294
+ ==========
295
+
296
+ .. [1] https://en.wikipedia.org/wiki/Gauss%E2%80%93Laguerre_quadrature
297
+ .. [2] https://people.sc.fsu.edu/~jburkardt/cpp_src/gen_laguerre_rule/gen_laguerre_rule.html
298
+ """
299
+ x = Dummy("x")
300
+ p = laguerre_poly(n, x, alpha=alpha, polys=True)
301
+ p1 = laguerre_poly(n-1, x, alpha=alpha, polys=True)
302
+ p2 = laguerre_poly(n-1, x, alpha=alpha+1, polys=True)
303
+ xi = []
304
+ w = []
305
+ for r in p.real_roots():
306
+ if isinstance(r, RootOf):
307
+ r = r.eval_rational(S.One/10**(n_digits+2))
308
+ xi.append(r.n(n_digits))
309
+ w.append((gamma(alpha+n) /
310
+ (n*gamma(n)*p1.subs(x, r)*p2.subs(x, r))).n(n_digits))
311
+ return xi, w
312
+
313
+
314
+ def gauss_chebyshev_t(n, n_digits):
315
+ r"""
316
+ Computes the Gauss-Chebyshev quadrature [1]_ points and weights of
317
+ the first kind.
318
+
319
+ Explanation
320
+ ===========
321
+
322
+ The Gauss-Chebyshev quadrature of the first kind approximates the integral:
323
+
324
+ .. math::
325
+ \int_{-1}^{1} \frac{1}{\sqrt{1-x^2}} f(x)\,dx \approx
326
+ \sum_{i=1}^n w_i f(x_i)
327
+
328
+ The nodes `x_i` of an order `n` quadrature rule are the roots of `T_n`
329
+ and the weights `w_i` are given by:
330
+
331
+ .. math::
332
+ w_i = \frac{\pi}{n}
333
+
334
+ Parameters
335
+ ==========
336
+
337
+ n :
338
+ The order of quadrature.
339
+
340
+ n_digits :
341
+ Number of significant digits of the points and weights to return.
342
+
343
+ Returns
344
+ =======
345
+
346
+ (x, w) : the ``x`` and ``w`` are lists of points and weights as Floats.
347
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
348
+ tuple of lists.
349
+
350
+ Examples
351
+ ========
352
+
353
+ >>> from sympy.integrals.quadrature import gauss_chebyshev_t
354
+ >>> x, w = gauss_chebyshev_t(3, 5)
355
+ >>> x
356
+ [0.86602, 0, -0.86602]
357
+ >>> w
358
+ [1.0472, 1.0472, 1.0472]
359
+
360
+ >>> x, w = gauss_chebyshev_t(6, 5)
361
+ >>> x
362
+ [0.96593, 0.70711, 0.25882, -0.25882, -0.70711, -0.96593]
363
+ >>> w
364
+ [0.5236, 0.5236, 0.5236, 0.5236, 0.5236, 0.5236]
365
+
366
+ See Also
367
+ ========
368
+
369
+ gauss_legendre, gauss_laguerre, gauss_hermite, gauss_gen_laguerre, gauss_chebyshev_u, gauss_jacobi, gauss_lobatto
370
+
371
+ References
372
+ ==========
373
+
374
+ .. [1] https://en.wikipedia.org/wiki/Chebyshev%E2%80%93Gauss_quadrature
375
+ .. [2] https://people.sc.fsu.edu/~jburkardt/cpp_src/chebyshev1_rule/chebyshev1_rule.html
376
+ """
377
+ xi = []
378
+ w = []
379
+ for i in range(1, n+1):
380
+ xi.append((cos((2*i-S.One)/(2*n)*S.Pi)).n(n_digits))
381
+ w.append((S.Pi/n).n(n_digits))
382
+ return xi, w
383
+
384
+
385
+ def gauss_chebyshev_u(n, n_digits):
386
+ r"""
387
+ Computes the Gauss-Chebyshev quadrature [1]_ points and weights of
388
+ the second kind.
389
+
390
+ Explanation
391
+ ===========
392
+
393
+ The Gauss-Chebyshev quadrature of the second kind approximates the
394
+ integral:
395
+
396
+ .. math::
397
+ \int_{-1}^{1} \sqrt{1-x^2} f(x)\,dx \approx \sum_{i=1}^n w_i f(x_i)
398
+
399
+ The nodes `x_i` of an order `n` quadrature rule are the roots of `U_n`
400
+ and the weights `w_i` are given by:
401
+
402
+ .. math::
403
+ w_i = \frac{\pi}{n+1} \sin^2 \left(\frac{i}{n+1}\pi\right)
404
+
405
+ Parameters
406
+ ==========
407
+
408
+ n : the order of quadrature
409
+
410
+ n_digits : number of significant digits of the points and weights to return
411
+
412
+ Returns
413
+ =======
414
+
415
+ (x, w) : the ``x`` and ``w`` are lists of points and weights as Floats.
416
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
417
+ tuple of lists.
418
+
419
+ Examples
420
+ ========
421
+
422
+ >>> from sympy.integrals.quadrature import gauss_chebyshev_u
423
+ >>> x, w = gauss_chebyshev_u(3, 5)
424
+ >>> x
425
+ [0.70711, 0, -0.70711]
426
+ >>> w
427
+ [0.3927, 0.7854, 0.3927]
428
+
429
+ >>> x, w = gauss_chebyshev_u(6, 5)
430
+ >>> x
431
+ [0.90097, 0.62349, 0.22252, -0.22252, -0.62349, -0.90097]
432
+ >>> w
433
+ [0.084489, 0.27433, 0.42658, 0.42658, 0.27433, 0.084489]
434
+
435
+ See Also
436
+ ========
437
+
438
+ gauss_legendre, gauss_laguerre, gauss_hermite, gauss_gen_laguerre, gauss_chebyshev_t, gauss_jacobi, gauss_lobatto
439
+
440
+ References
441
+ ==========
442
+
443
+ .. [1] https://en.wikipedia.org/wiki/Chebyshev%E2%80%93Gauss_quadrature
444
+ .. [2] https://people.sc.fsu.edu/~jburkardt/cpp_src/chebyshev2_rule/chebyshev2_rule.html
445
+ """
446
+ xi = []
447
+ w = []
448
+ for i in range(1, n+1):
449
+ xi.append((cos(i/(n+S.One)*S.Pi)).n(n_digits))
450
+ w.append((S.Pi/(n+S.One)*sin(i*S.Pi/(n+S.One))**2).n(n_digits))
451
+ return xi, w
452
+
453
+
454
+ def gauss_jacobi(n, alpha, beta, n_digits):
455
+ r"""
456
+ Computes the Gauss-Jacobi quadrature [1]_ points and weights.
457
+
458
+ Explanation
459
+ ===========
460
+
461
+ The Gauss-Jacobi quadrature of the first kind approximates the integral:
462
+
463
+ .. math::
464
+ \int_{-1}^1 (1-x)^\alpha (1+x)^\beta f(x)\,dx \approx
465
+ \sum_{i=1}^n w_i f(x_i)
466
+
467
+ The nodes `x_i` of an order `n` quadrature rule are the roots of
468
+ `P^{(\alpha,\beta)}_n` and the weights `w_i` are given by:
469
+
470
+ .. math::
471
+ w_i = -\frac{2n+\alpha+\beta+2}{n+\alpha+\beta+1}
472
+ \frac{\Gamma(n+\alpha+1)\Gamma(n+\beta+1)}
473
+ {\Gamma(n+\alpha+\beta+1)(n+1)!}
474
+ \frac{2^{\alpha+\beta}}{P'_n(x_i)
475
+ P^{(\alpha,\beta)}_{n+1}(x_i)}
476
+
477
+ Parameters
478
+ ==========
479
+
480
+ n : the order of quadrature
481
+
482
+ alpha : the first parameter of the Jacobi Polynomial, `\alpha > -1`
483
+
484
+ beta : the second parameter of the Jacobi Polynomial, `\beta > -1`
485
+
486
+ n_digits : number of significant digits of the points and weights to return
487
+
488
+ Returns
489
+ =======
490
+
491
+ (x, w) : the ``x`` and ``w`` are lists of points and weights as Floats.
492
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
493
+ tuple of lists.
494
+
495
+ Examples
496
+ ========
497
+
498
+ >>> from sympy import S
499
+ >>> from sympy.integrals.quadrature import gauss_jacobi
500
+ >>> x, w = gauss_jacobi(3, S.Half, -S.Half, 5)
501
+ >>> x
502
+ [-0.90097, -0.22252, 0.62349]
503
+ >>> w
504
+ [1.7063, 1.0973, 0.33795]
505
+
506
+ >>> x, w = gauss_jacobi(6, 1, 1, 5)
507
+ >>> x
508
+ [-0.87174, -0.5917, -0.2093, 0.2093, 0.5917, 0.87174]
509
+ >>> w
510
+ [0.050584, 0.22169, 0.39439, 0.39439, 0.22169, 0.050584]
511
+
512
+ See Also
513
+ ========
514
+
515
+ gauss_legendre, gauss_laguerre, gauss_hermite, gauss_gen_laguerre,
516
+ gauss_chebyshev_t, gauss_chebyshev_u, gauss_lobatto
517
+
518
+ References
519
+ ==========
520
+
521
+ .. [1] https://en.wikipedia.org/wiki/Gauss%E2%80%93Jacobi_quadrature
522
+ .. [2] https://people.sc.fsu.edu/~jburkardt/cpp_src/jacobi_rule/jacobi_rule.html
523
+ .. [3] https://people.sc.fsu.edu/~jburkardt/cpp_src/gegenbauer_rule/gegenbauer_rule.html
524
+ """
525
+ x = Dummy("x")
526
+ p = jacobi_poly(n, alpha, beta, x, polys=True)
527
+ pd = p.diff(x)
528
+ pn = jacobi_poly(n+1, alpha, beta, x, polys=True)
529
+ xi = []
530
+ w = []
531
+ for r in p.real_roots():
532
+ if isinstance(r, RootOf):
533
+ r = r.eval_rational(S.One/10**(n_digits+2))
534
+ xi.append(r.n(n_digits))
535
+ w.append((
536
+ - (2*n+alpha+beta+2) / (n+alpha+beta+S.One) *
537
+ (gamma(n+alpha+1)*gamma(n+beta+1)) /
538
+ (gamma(n+alpha+beta+S.One)*gamma(n+2)) *
539
+ 2**(alpha+beta) / (pd.subs(x, r) * pn.subs(x, r))).n(n_digits))
540
+ return xi, w
541
+
542
+
543
+ def gauss_lobatto(n, n_digits):
544
+ r"""
545
+ Computes the Gauss-Lobatto quadrature [1]_ points and weights.
546
+
547
+ Explanation
548
+ ===========
549
+
550
+ The Gauss-Lobatto quadrature approximates the integral:
551
+
552
+ .. math::
553
+ \int_{-1}^1 f(x)\,dx \approx \sum_{i=1}^n w_i f(x_i)
554
+
555
+ The nodes `x_i` of an order `n` quadrature rule are the roots of `P'_(n-1)`
556
+ and the weights `w_i` are given by:
557
+
558
+ .. math::
559
+ &w_i = \frac{2}{n(n-1) \left[P_{n-1}(x_i)\right]^2},\quad x\neq\pm 1\\
560
+ &w_i = \frac{2}{n(n-1)},\quad x=\pm 1
561
+
562
+ Parameters
563
+ ==========
564
+
565
+ n : the order of quadrature
566
+
567
+ n_digits : number of significant digits of the points and weights to return
568
+
569
+ Returns
570
+ =======
571
+
572
+ (x, w) : the ``x`` and ``w`` are lists of points and weights as Floats.
573
+ The points `x_i` and weights `w_i` are returned as ``(x, w)``
574
+ tuple of lists.
575
+
576
+ Examples
577
+ ========
578
+
579
+ >>> from sympy.integrals.quadrature import gauss_lobatto
580
+ >>> x, w = gauss_lobatto(3, 5)
581
+ >>> x
582
+ [-1, 0, 1]
583
+ >>> w
584
+ [0.33333, 1.3333, 0.33333]
585
+ >>> x, w = gauss_lobatto(4, 5)
586
+ >>> x
587
+ [-1, -0.44721, 0.44721, 1]
588
+ >>> w
589
+ [0.16667, 0.83333, 0.83333, 0.16667]
590
+
591
+ See Also
592
+ ========
593
+
594
+ gauss_legendre,gauss_laguerre, gauss_gen_laguerre, gauss_hermite, gauss_chebyshev_t, gauss_chebyshev_u, gauss_jacobi
595
+
596
+ References
597
+ ==========
598
+
599
+ .. [1] https://en.wikipedia.org/wiki/Gaussian_quadrature#Gauss.E2.80.93Lobatto_rules
600
+ .. [2] https://web.archive.org/web/20200118141346/http://people.math.sfu.ca/~cbm/aands/page_888.htm
601
+ """
602
+ x = Dummy("x")
603
+ p = legendre_poly(n-1, x, polys=True)
604
+ pd = p.diff(x)
605
+ xi = []
606
+ w = []
607
+ for r in pd.real_roots():
608
+ if isinstance(r, RootOf):
609
+ r = r.eval_rational(S.One/10**(n_digits+2))
610
+ xi.append(r.n(n_digits))
611
+ w.append((2/(n*(n-1) * p.subs(x, r)**2)).n(n_digits))
612
+
613
+ xi.insert(0, -1)
614
+ xi.append(1)
615
+ w.insert(0, (S(2)/(n*(n-1))).n(n_digits))
616
+ w.append((S(2)/(n*(n-1))).n(n_digits))
617
+ return xi, w
venv/lib/python3.10/site-packages/sympy/integrals/rationaltools.py ADDED
@@ -0,0 +1,418 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """This module implements tools for integrating rational functions. """
2
+
3
+ from sympy.core.function import Lambda
4
+ from sympy.core.numbers import I
5
+ from sympy.core.singleton import S
6
+ from sympy.core.symbol import (Dummy, Symbol, symbols)
7
+ from sympy.functions.elementary.exponential import log
8
+ from sympy.functions.elementary.trigonometric import atan
9
+ from sympy.polys.polyroots import roots
10
+ from sympy.polys.polytools import cancel
11
+ from sympy.polys.rootoftools import RootSum
12
+ from sympy.polys import Poly, resultant, ZZ
13
+
14
+
15
+ def ratint(f, x, **flags):
16
+ """
17
+ Performs indefinite integration of rational functions.
18
+
19
+ Explanation
20
+ ===========
21
+
22
+ Given a field :math:`K` and a rational function :math:`f = p/q`,
23
+ where :math:`p` and :math:`q` are polynomials in :math:`K[x]`,
24
+ returns a function :math:`g` such that :math:`f = g'`.
25
+
26
+ Examples
27
+ ========
28
+
29
+ >>> from sympy.integrals.rationaltools import ratint
30
+ >>> from sympy.abc import x
31
+
32
+ >>> ratint(36/(x**5 - 2*x**4 - 2*x**3 + 4*x**2 + x - 2), x)
33
+ (12*x + 6)/(x**2 - 1) + 4*log(x - 2) - 4*log(x + 1)
34
+
35
+ References
36
+ ==========
37
+
38
+ .. [1] M. Bronstein, Symbolic Integration I: Transcendental
39
+ Functions, Second Edition, Springer-Verlag, 2005, pp. 35-70
40
+
41
+ See Also
42
+ ========
43
+
44
+ sympy.integrals.integrals.Integral.doit
45
+ sympy.integrals.rationaltools.ratint_logpart
46
+ sympy.integrals.rationaltools.ratint_ratpart
47
+
48
+ """
49
+ if isinstance(f, tuple):
50
+ p, q = f
51
+ else:
52
+ p, q = f.as_numer_denom()
53
+
54
+ p, q = Poly(p, x, composite=False, field=True), Poly(q, x, composite=False, field=True)
55
+
56
+ coeff, p, q = p.cancel(q)
57
+ poly, p = p.div(q)
58
+
59
+ result = poly.integrate(x).as_expr()
60
+
61
+ if p.is_zero:
62
+ return coeff*result
63
+
64
+ g, h = ratint_ratpart(p, q, x)
65
+
66
+ P, Q = h.as_numer_denom()
67
+
68
+ P = Poly(P, x)
69
+ Q = Poly(Q, x)
70
+
71
+ q, r = P.div(Q)
72
+
73
+ result += g + q.integrate(x).as_expr()
74
+
75
+ if not r.is_zero:
76
+ symbol = flags.get('symbol', 't')
77
+
78
+ if not isinstance(symbol, Symbol):
79
+ t = Dummy(symbol)
80
+ else:
81
+ t = symbol.as_dummy()
82
+
83
+ L = ratint_logpart(r, Q, x, t)
84
+
85
+ real = flags.get('real')
86
+
87
+ if real is None:
88
+ if isinstance(f, tuple):
89
+ p, q = f
90
+ atoms = p.atoms() | q.atoms()
91
+ else:
92
+ atoms = f.atoms()
93
+
94
+ for elt in atoms - {x}:
95
+ if not elt.is_extended_real:
96
+ real = False
97
+ break
98
+ else:
99
+ real = True
100
+
101
+ eps = S.Zero
102
+
103
+ if not real:
104
+ for h, q in L:
105
+ _, h = h.primitive()
106
+ eps += RootSum(
107
+ q, Lambda(t, t*log(h.as_expr())), quadratic=True)
108
+ else:
109
+ for h, q in L:
110
+ _, h = h.primitive()
111
+ R = log_to_real(h, q, x, t)
112
+
113
+ if R is not None:
114
+ eps += R
115
+ else:
116
+ eps += RootSum(
117
+ q, Lambda(t, t*log(h.as_expr())), quadratic=True)
118
+
119
+ result += eps
120
+
121
+ return coeff*result
122
+
123
+
124
+ def ratint_ratpart(f, g, x):
125
+ """
126
+ Horowitz-Ostrogradsky algorithm.
127
+
128
+ Explanation
129
+ ===========
130
+
131
+ Given a field K and polynomials f and g in K[x], such that f and g
132
+ are coprime and deg(f) < deg(g), returns fractions A and B in K(x),
133
+ such that f/g = A' + B and B has square-free denominator.
134
+
135
+ Examples
136
+ ========
137
+
138
+ >>> from sympy.integrals.rationaltools import ratint_ratpart
139
+ >>> from sympy.abc import x, y
140
+ >>> from sympy import Poly
141
+ >>> ratint_ratpart(Poly(1, x, domain='ZZ'),
142
+ ... Poly(x + 1, x, domain='ZZ'), x)
143
+ (0, 1/(x + 1))
144
+ >>> ratint_ratpart(Poly(1, x, domain='EX'),
145
+ ... Poly(x**2 + y**2, x, domain='EX'), x)
146
+ (0, 1/(x**2 + y**2))
147
+ >>> ratint_ratpart(Poly(36, x, domain='ZZ'),
148
+ ... Poly(x**5 - 2*x**4 - 2*x**3 + 4*x**2 + x - 2, x, domain='ZZ'), x)
149
+ ((12*x + 6)/(x**2 - 1), 12/(x**2 - x - 2))
150
+
151
+ See Also
152
+ ========
153
+
154
+ ratint, ratint_logpart
155
+ """
156
+ from sympy.solvers.solvers import solve
157
+
158
+ f = Poly(f, x)
159
+ g = Poly(g, x)
160
+
161
+ u, v, _ = g.cofactors(g.diff())
162
+
163
+ n = u.degree()
164
+ m = v.degree()
165
+
166
+ A_coeffs = [ Dummy('a' + str(n - i)) for i in range(0, n) ]
167
+ B_coeffs = [ Dummy('b' + str(m - i)) for i in range(0, m) ]
168
+
169
+ C_coeffs = A_coeffs + B_coeffs
170
+
171
+ A = Poly(A_coeffs, x, domain=ZZ[C_coeffs])
172
+ B = Poly(B_coeffs, x, domain=ZZ[C_coeffs])
173
+
174
+ H = f - A.diff()*v + A*(u.diff()*v).quo(u) - B*u
175
+
176
+ result = solve(H.coeffs(), C_coeffs)
177
+
178
+ A = A.as_expr().subs(result)
179
+ B = B.as_expr().subs(result)
180
+
181
+ rat_part = cancel(A/u.as_expr(), x)
182
+ log_part = cancel(B/v.as_expr(), x)
183
+
184
+ return rat_part, log_part
185
+
186
+
187
+ def ratint_logpart(f, g, x, t=None):
188
+ r"""
189
+ Lazard-Rioboo-Trager algorithm.
190
+
191
+ Explanation
192
+ ===========
193
+
194
+ Given a field K and polynomials f and g in K[x], such that f and g
195
+ are coprime, deg(f) < deg(g) and g is square-free, returns a list
196
+ of tuples (s_i, q_i) of polynomials, for i = 1..n, such that s_i
197
+ in K[t, x] and q_i in K[t], and::
198
+
199
+ ___ ___
200
+ d f d \ ` \ `
201
+ -- - = -- ) ) a log(s_i(a, x))
202
+ dx g dx /__, /__,
203
+ i=1..n a | q_i(a) = 0
204
+
205
+ Examples
206
+ ========
207
+
208
+ >>> from sympy.integrals.rationaltools import ratint_logpart
209
+ >>> from sympy.abc import x
210
+ >>> from sympy import Poly
211
+ >>> ratint_logpart(Poly(1, x, domain='ZZ'),
212
+ ... Poly(x**2 + x + 1, x, domain='ZZ'), x)
213
+ [(Poly(x + 3*_t/2 + 1/2, x, domain='QQ[_t]'),
214
+ ...Poly(3*_t**2 + 1, _t, domain='ZZ'))]
215
+ >>> ratint_logpart(Poly(12, x, domain='ZZ'),
216
+ ... Poly(x**2 - x - 2, x, domain='ZZ'), x)
217
+ [(Poly(x - 3*_t/8 - 1/2, x, domain='QQ[_t]'),
218
+ ...Poly(-_t**2 + 16, _t, domain='ZZ'))]
219
+
220
+ See Also
221
+ ========
222
+
223
+ ratint, ratint_ratpart
224
+ """
225
+ f, g = Poly(f, x), Poly(g, x)
226
+
227
+ t = t or Dummy('t')
228
+ a, b = g, f - g.diff()*Poly(t, x)
229
+
230
+ res, R = resultant(a, b, includePRS=True)
231
+ res = Poly(res, t, composite=False)
232
+
233
+ assert res, "BUG: resultant(%s, %s) cannot be zero" % (a, b)
234
+
235
+ R_map, H = {}, []
236
+
237
+ for r in R:
238
+ R_map[r.degree()] = r
239
+
240
+ def _include_sign(c, sqf):
241
+ if c.is_extended_real and (c < 0) == True:
242
+ h, k = sqf[0]
243
+ c_poly = c.as_poly(h.gens)
244
+ sqf[0] = h*c_poly, k
245
+
246
+ C, res_sqf = res.sqf_list()
247
+ _include_sign(C, res_sqf)
248
+
249
+ for q, i in res_sqf:
250
+ _, q = q.primitive()
251
+
252
+ if g.degree() == i:
253
+ H.append((g, q))
254
+ else:
255
+ h = R_map[i]
256
+ h_lc = Poly(h.LC(), t, field=True)
257
+
258
+ c, h_lc_sqf = h_lc.sqf_list(all=True)
259
+ _include_sign(c, h_lc_sqf)
260
+
261
+ for a, j in h_lc_sqf:
262
+ h = h.quo(Poly(a.gcd(q)**j, x))
263
+
264
+ inv, coeffs = h_lc.invert(q), [S.One]
265
+
266
+ for coeff in h.coeffs()[1:]:
267
+ coeff = coeff.as_poly(inv.gens)
268
+ T = (inv*coeff).rem(q)
269
+ coeffs.append(T.as_expr())
270
+
271
+ h = Poly(dict(list(zip(h.monoms(), coeffs))), x)
272
+
273
+ H.append((h, q))
274
+
275
+ return H
276
+
277
+
278
+ def log_to_atan(f, g):
279
+ """
280
+ Convert complex logarithms to real arctangents.
281
+
282
+ Explanation
283
+ ===========
284
+
285
+ Given a real field K and polynomials f and g in K[x], with g != 0,
286
+ returns a sum h of arctangents of polynomials in K[x], such that:
287
+
288
+ dh d f + I g
289
+ -- = -- I log( ------- )
290
+ dx dx f - I g
291
+
292
+ Examples
293
+ ========
294
+
295
+ >>> from sympy.integrals.rationaltools import log_to_atan
296
+ >>> from sympy.abc import x
297
+ >>> from sympy import Poly, sqrt, S
298
+ >>> log_to_atan(Poly(x, x, domain='ZZ'), Poly(1, x, domain='ZZ'))
299
+ 2*atan(x)
300
+ >>> log_to_atan(Poly(x + S(1)/2, x, domain='QQ'),
301
+ ... Poly(sqrt(3)/2, x, domain='EX'))
302
+ 2*atan(2*sqrt(3)*x/3 + sqrt(3)/3)
303
+
304
+ See Also
305
+ ========
306
+
307
+ log_to_real
308
+ """
309
+ if f.degree() < g.degree():
310
+ f, g = -g, f
311
+
312
+ f = f.to_field()
313
+ g = g.to_field()
314
+
315
+ p, q = f.div(g)
316
+
317
+ if q.is_zero:
318
+ return 2*atan(p.as_expr())
319
+ else:
320
+ s, t, h = g.gcdex(-f)
321
+ u = (f*s + g*t).quo(h)
322
+ A = 2*atan(u.as_expr())
323
+
324
+ return A + log_to_atan(s, t)
325
+
326
+
327
+ def log_to_real(h, q, x, t):
328
+ r"""
329
+ Convert complex logarithms to real functions.
330
+
331
+ Explanation
332
+ ===========
333
+
334
+ Given real field K and polynomials h in K[t,x] and q in K[t],
335
+ returns real function f such that:
336
+ ___
337
+ df d \ `
338
+ -- = -- ) a log(h(a, x))
339
+ dx dx /__,
340
+ a | q(a) = 0
341
+
342
+ Examples
343
+ ========
344
+
345
+ >>> from sympy.integrals.rationaltools import log_to_real
346
+ >>> from sympy.abc import x, y
347
+ >>> from sympy import Poly, S
348
+ >>> log_to_real(Poly(x + 3*y/2 + S(1)/2, x, domain='QQ[y]'),
349
+ ... Poly(3*y**2 + 1, y, domain='ZZ'), x, y)
350
+ 2*sqrt(3)*atan(2*sqrt(3)*x/3 + sqrt(3)/3)/3
351
+ >>> log_to_real(Poly(x**2 - 1, x, domain='ZZ'),
352
+ ... Poly(-2*y + 1, y, domain='ZZ'), x, y)
353
+ log(x**2 - 1)/2
354
+
355
+ See Also
356
+ ========
357
+
358
+ log_to_atan
359
+ """
360
+ from sympy.simplify.radsimp import collect
361
+ u, v = symbols('u,v', cls=Dummy)
362
+
363
+ H = h.as_expr().subs({t: u + I*v}).expand()
364
+ Q = q.as_expr().subs({t: u + I*v}).expand()
365
+
366
+ H_map = collect(H, I, evaluate=False)
367
+ Q_map = collect(Q, I, evaluate=False)
368
+
369
+ a, b = H_map.get(S.One, S.Zero), H_map.get(I, S.Zero)
370
+ c, d = Q_map.get(S.One, S.Zero), Q_map.get(I, S.Zero)
371
+
372
+ R = Poly(resultant(c, d, v), u)
373
+
374
+ R_u = roots(R, filter='R')
375
+
376
+ if len(R_u) != R.count_roots():
377
+ return None
378
+
379
+ result = S.Zero
380
+
381
+ for r_u in R_u.keys():
382
+ C = Poly(c.subs({u: r_u}), v)
383
+ R_v = roots(C, filter='R')
384
+
385
+ if len(R_v) != C.count_roots():
386
+ return None
387
+
388
+ R_v_paired = [] # take one from each pair of conjugate roots
389
+ for r_v in R_v:
390
+ if r_v not in R_v_paired and -r_v not in R_v_paired:
391
+ if r_v.is_negative or r_v.could_extract_minus_sign():
392
+ R_v_paired.append(-r_v)
393
+ elif not r_v.is_zero:
394
+ R_v_paired.append(r_v)
395
+
396
+ for r_v in R_v_paired:
397
+
398
+ D = d.subs({u: r_u, v: r_v})
399
+
400
+ if D.evalf(chop=True) != 0:
401
+ continue
402
+
403
+ A = Poly(a.subs({u: r_u, v: r_v}), x)
404
+ B = Poly(b.subs({u: r_u, v: r_v}), x)
405
+
406
+ AB = (A**2 + B**2).as_expr()
407
+
408
+ result += r_u*log(AB) + r_v*log_to_atan(A, B)
409
+
410
+ R_q = roots(q, filter='R')
411
+
412
+ if len(R_q) != q.count_roots():
413
+ return None
414
+
415
+ for r in R_q.keys():
416
+ result += r*log(h.as_expr().subs(t, r))
417
+
418
+ return result
venv/lib/python3.10/site-packages/sympy/integrals/rde.py ADDED
@@ -0,0 +1,800 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """
2
+ Algorithms for solving the Risch differential equation.
3
+
4
+ Given a differential field K of characteristic 0 that is a simple
5
+ monomial extension of a base field k and f, g in K, the Risch
6
+ Differential Equation problem is to decide if there exist y in K such
7
+ that Dy + f*y == g and to find one if there are some. If t is a
8
+ monomial over k and the coefficients of f and g are in k(t), then y is
9
+ in k(t), and the outline of the algorithm here is given as:
10
+
11
+ 1. Compute the normal part n of the denominator of y. The problem is
12
+ then reduced to finding y' in k<t>, where y == y'/n.
13
+ 2. Compute the special part s of the denominator of y. The problem is
14
+ then reduced to finding y'' in k[t], where y == y''/(n*s)
15
+ 3. Bound the degree of y''.
16
+ 4. Reduce the equation Dy + f*y == g to a similar equation with f, g in
17
+ k[t].
18
+ 5. Find the solutions in k[t] of bounded degree of the reduced equation.
19
+
20
+ See Chapter 6 of "Symbolic Integration I: Transcendental Functions" by
21
+ Manuel Bronstein. See also the docstring of risch.py.
22
+ """
23
+
24
+ from operator import mul
25
+ from functools import reduce
26
+
27
+ from sympy.core import oo
28
+ from sympy.core.symbol import Dummy
29
+
30
+ from sympy.polys import Poly, gcd, ZZ, cancel
31
+
32
+ from sympy.functions.elementary.complexes import (im, re)
33
+ from sympy.functions.elementary.miscellaneous import sqrt
34
+
35
+ from sympy.integrals.risch import (gcdex_diophantine, frac_in, derivation,
36
+ splitfactor, NonElementaryIntegralException, DecrementLevel, recognize_log_derivative)
37
+
38
+ # TODO: Add messages to NonElementaryIntegralException errors
39
+
40
+
41
+ def order_at(a, p, t):
42
+ """
43
+ Computes the order of a at p, with respect to t.
44
+
45
+ Explanation
46
+ ===========
47
+
48
+ For a, p in k[t], the order of a at p is defined as nu_p(a) = max({n
49
+ in Z+ such that p**n|a}), where a != 0. If a == 0, nu_p(a) = +oo.
50
+
51
+ To compute the order at a rational function, a/b, use the fact that
52
+ nu_p(a/b) == nu_p(a) - nu_p(b).
53
+ """
54
+ if a.is_zero:
55
+ return oo
56
+ if p == Poly(t, t):
57
+ return a.as_poly(t).ET()[0][0]
58
+
59
+ # Uses binary search for calculating the power. power_list collects the tuples
60
+ # (p^k,k) where each k is some power of 2. After deciding the largest k
61
+ # such that k is power of 2 and p^k|a the loop iteratively calculates
62
+ # the actual power.
63
+ power_list = []
64
+ p1 = p
65
+ r = a.rem(p1)
66
+ tracks_power = 1
67
+ while r.is_zero:
68
+ power_list.append((p1,tracks_power))
69
+ p1 = p1*p1
70
+ tracks_power *= 2
71
+ r = a.rem(p1)
72
+ n = 0
73
+ product = Poly(1, t)
74
+ while len(power_list) != 0:
75
+ final = power_list.pop()
76
+ productf = product*final[0]
77
+ r = a.rem(productf)
78
+ if r.is_zero:
79
+ n += final[1]
80
+ product = productf
81
+ return n
82
+
83
+
84
+ def order_at_oo(a, d, t):
85
+ """
86
+ Computes the order of a/d at oo (infinity), with respect to t.
87
+
88
+ For f in k(t), the order or f at oo is defined as deg(d) - deg(a), where
89
+ f == a/d.
90
+ """
91
+ if a.is_zero:
92
+ return oo
93
+ return d.degree(t) - a.degree(t)
94
+
95
+
96
+ def weak_normalizer(a, d, DE, z=None):
97
+ """
98
+ Weak normalization.
99
+
100
+ Explanation
101
+ ===========
102
+
103
+ Given a derivation D on k[t] and f == a/d in k(t), return q in k[t]
104
+ such that f - Dq/q is weakly normalized with respect to t.
105
+
106
+ f in k(t) is said to be "weakly normalized" with respect to t if
107
+ residue_p(f) is not a positive integer for any normal irreducible p
108
+ in k[t] such that f is in R_p (Definition 6.1.1). If f has an
109
+ elementary integral, this is equivalent to no logarithm of
110
+ integral(f) whose argument depends on t has a positive integer
111
+ coefficient, where the arguments of the logarithms not in k(t) are
112
+ in k[t].
113
+
114
+ Returns (q, f - Dq/q)
115
+ """
116
+ z = z or Dummy('z')
117
+ dn, ds = splitfactor(d, DE)
118
+
119
+ # Compute d1, where dn == d1*d2**2*...*dn**n is a square-free
120
+ # factorization of d.
121
+ g = gcd(dn, dn.diff(DE.t))
122
+ d_sqf_part = dn.quo(g)
123
+ d1 = d_sqf_part.quo(gcd(d_sqf_part, g))
124
+
125
+ a1, b = gcdex_diophantine(d.quo(d1).as_poly(DE.t), d1.as_poly(DE.t),
126
+ a.as_poly(DE.t))
127
+ r = (a - Poly(z, DE.t)*derivation(d1, DE)).as_poly(DE.t).resultant(
128
+ d1.as_poly(DE.t))
129
+ r = Poly(r, z)
130
+
131
+ if not r.expr.has(z):
132
+ return (Poly(1, DE.t), (a, d))
133
+
134
+ N = [i for i in r.real_roots() if i in ZZ and i > 0]
135
+
136
+ q = reduce(mul, [gcd(a - Poly(n, DE.t)*derivation(d1, DE), d1) for n in N],
137
+ Poly(1, DE.t))
138
+
139
+ dq = derivation(q, DE)
140
+ sn = q*a - d*dq
141
+ sd = q*d
142
+ sn, sd = sn.cancel(sd, include=True)
143
+
144
+ return (q, (sn, sd))
145
+
146
+
147
+ def normal_denom(fa, fd, ga, gd, DE):
148
+ """
149
+ Normal part of the denominator.
150
+
151
+ Explanation
152
+ ===========
153
+
154
+ Given a derivation D on k[t] and f, g in k(t) with f weakly
155
+ normalized with respect to t, either raise NonElementaryIntegralException,
156
+ in which case the equation Dy + f*y == g has no solution in k(t), or the
157
+ quadruplet (a, b, c, h) such that a, h in k[t], b, c in k<t>, and for any
158
+ solution y in k(t) of Dy + f*y == g, q = y*h in k<t> satisfies
159
+ a*Dq + b*q == c.
160
+
161
+ This constitutes step 1 in the outline given in the rde.py docstring.
162
+ """
163
+ dn, ds = splitfactor(fd, DE)
164
+ en, es = splitfactor(gd, DE)
165
+
166
+ p = dn.gcd(en)
167
+ h = en.gcd(en.diff(DE.t)).quo(p.gcd(p.diff(DE.t)))
168
+
169
+ a = dn*h
170
+ c = a*h
171
+ if c.div(en)[1]:
172
+ # en does not divide dn*h**2
173
+ raise NonElementaryIntegralException
174
+ ca = c*ga
175
+ ca, cd = ca.cancel(gd, include=True)
176
+
177
+ ba = a*fa - dn*derivation(h, DE)*fd
178
+ ba, bd = ba.cancel(fd, include=True)
179
+
180
+ # (dn*h, dn*h*f - dn*Dh, dn*h**2*g, h)
181
+ return (a, (ba, bd), (ca, cd), h)
182
+
183
+
184
+ def special_denom(a, ba, bd, ca, cd, DE, case='auto'):
185
+ """
186
+ Special part of the denominator.
187
+
188
+ Explanation
189
+ ===========
190
+
191
+ case is one of {'exp', 'tan', 'primitive'} for the hyperexponential,
192
+ hypertangent, and primitive cases, respectively. For the
193
+ hyperexponential (resp. hypertangent) case, given a derivation D on
194
+ k[t] and a in k[t], b, c, in k<t> with Dt/t in k (resp. Dt/(t**2 + 1) in
195
+ k, sqrt(-1) not in k), a != 0, and gcd(a, t) == 1 (resp.
196
+ gcd(a, t**2 + 1) == 1), return the quadruplet (A, B, C, 1/h) such that
197
+ A, B, C, h in k[t] and for any solution q in k<t> of a*Dq + b*q == c,
198
+ r = qh in k[t] satisfies A*Dr + B*r == C.
199
+
200
+ For ``case == 'primitive'``, k<t> == k[t], so it returns (a, b, c, 1) in
201
+ this case.
202
+
203
+ This constitutes step 2 of the outline given in the rde.py docstring.
204
+ """
205
+ # TODO: finish writing this and write tests
206
+
207
+ if case == 'auto':
208
+ case = DE.case
209
+
210
+ if case == 'exp':
211
+ p = Poly(DE.t, DE.t)
212
+ elif case == 'tan':
213
+ p = Poly(DE.t**2 + 1, DE.t)
214
+ elif case in ('primitive', 'base'):
215
+ B = ba.to_field().quo(bd)
216
+ C = ca.to_field().quo(cd)
217
+ return (a, B, C, Poly(1, DE.t))
218
+ else:
219
+ raise ValueError("case must be one of {'exp', 'tan', 'primitive', "
220
+ "'base'}, not %s." % case)
221
+
222
+ nb = order_at(ba, p, DE.t) - order_at(bd, p, DE.t)
223
+ nc = order_at(ca, p, DE.t) - order_at(cd, p, DE.t)
224
+
225
+ n = min(0, nc - min(0, nb))
226
+ if not nb:
227
+ # Possible cancellation.
228
+ from .prde import parametric_log_deriv
229
+ if case == 'exp':
230
+ dcoeff = DE.d.quo(Poly(DE.t, DE.t))
231
+ with DecrementLevel(DE): # We are guaranteed to not have problems,
232
+ # because case != 'base'.
233
+ alphaa, alphad = frac_in(-ba.eval(0)/bd.eval(0)/a.eval(0), DE.t)
234
+ etaa, etad = frac_in(dcoeff, DE.t)
235
+ A = parametric_log_deriv(alphaa, alphad, etaa, etad, DE)
236
+ if A is not None:
237
+ Q, m, z = A
238
+ if Q == 1:
239
+ n = min(n, m)
240
+
241
+ elif case == 'tan':
242
+ dcoeff = DE.d.quo(Poly(DE.t**2+1, DE.t))
243
+ with DecrementLevel(DE): # We are guaranteed to not have problems,
244
+ # because case != 'base'.
245
+ alphaa, alphad = frac_in(im(-ba.eval(sqrt(-1))/bd.eval(sqrt(-1))/a.eval(sqrt(-1))), DE.t)
246
+ betaa, betad = frac_in(re(-ba.eval(sqrt(-1))/bd.eval(sqrt(-1))/a.eval(sqrt(-1))), DE.t)
247
+ etaa, etad = frac_in(dcoeff, DE.t)
248
+
249
+ if recognize_log_derivative(Poly(2, DE.t)*betaa, betad, DE):
250
+ A = parametric_log_deriv(alphaa*Poly(sqrt(-1), DE.t)*betad+alphad*betaa, alphad*betad, etaa, etad, DE)
251
+ if A is not None:
252
+ Q, m, z = A
253
+ if Q == 1:
254
+ n = min(n, m)
255
+ N = max(0, -nb, n - nc)
256
+ pN = p**N
257
+ pn = p**-n
258
+
259
+ A = a*pN
260
+ B = ba*pN.quo(bd) + Poly(n, DE.t)*a*derivation(p, DE).quo(p)*pN
261
+ C = (ca*pN*pn).quo(cd)
262
+ h = pn
263
+
264
+ # (a*p**N, (b + n*a*Dp/p)*p**N, c*p**(N - n), p**-n)
265
+ return (A, B, C, h)
266
+
267
+
268
+ def bound_degree(a, b, cQ, DE, case='auto', parametric=False):
269
+ """
270
+ Bound on polynomial solutions.
271
+
272
+ Explanation
273
+ ===========
274
+
275
+ Given a derivation D on k[t] and ``a``, ``b``, ``c`` in k[t] with ``a != 0``, return
276
+ n in ZZ such that deg(q) <= n for any solution q in k[t] of
277
+ a*Dq + b*q == c, when parametric=False, or deg(q) <= n for any solution
278
+ c1, ..., cm in Const(k) and q in k[t] of a*Dq + b*q == Sum(ci*gi, (i, 1, m))
279
+ when parametric=True.
280
+
281
+ For ``parametric=False``, ``cQ`` is ``c``, a ``Poly``; for ``parametric=True``, ``cQ`` is Q ==
282
+ [q1, ..., qm], a list of Polys.
283
+
284
+ This constitutes step 3 of the outline given in the rde.py docstring.
285
+ """
286
+ # TODO: finish writing this and write tests
287
+
288
+ if case == 'auto':
289
+ case = DE.case
290
+
291
+ da = a.degree(DE.t)
292
+ db = b.degree(DE.t)
293
+
294
+ # The parametric and regular cases are identical, except for this part
295
+ if parametric:
296
+ dc = max([i.degree(DE.t) for i in cQ])
297
+ else:
298
+ dc = cQ.degree(DE.t)
299
+
300
+ alpha = cancel(-b.as_poly(DE.t).LC().as_expr()/
301
+ a.as_poly(DE.t).LC().as_expr())
302
+
303
+ if case == 'base':
304
+ n = max(0, dc - max(db, da - 1))
305
+ if db == da - 1 and alpha.is_Integer:
306
+ n = max(0, alpha, dc - db)
307
+
308
+ elif case == 'primitive':
309
+ if db > da:
310
+ n = max(0, dc - db)
311
+ else:
312
+ n = max(0, dc - da + 1)
313
+
314
+ etaa, etad = frac_in(DE.d, DE.T[DE.level - 1])
315
+
316
+ t1 = DE.t
317
+ with DecrementLevel(DE):
318
+ alphaa, alphad = frac_in(alpha, DE.t)
319
+ if db == da - 1:
320
+ from .prde import limited_integrate
321
+ # if alpha == m*Dt + Dz for z in k and m in ZZ:
322
+ try:
323
+ (za, zd), m = limited_integrate(alphaa, alphad, [(etaa, etad)],
324
+ DE)
325
+ except NonElementaryIntegralException:
326
+ pass
327
+ else:
328
+ if len(m) != 1:
329
+ raise ValueError("Length of m should be 1")
330
+ n = max(n, m[0])
331
+
332
+ elif db == da:
333
+ # if alpha == Dz/z for z in k*:
334
+ # beta = -lc(a*Dz + b*z)/(z*lc(a))
335
+ # if beta == m*Dt + Dw for w in k and m in ZZ:
336
+ # n = max(n, m)
337
+ from .prde import is_log_deriv_k_t_radical_in_field
338
+ A = is_log_deriv_k_t_radical_in_field(alphaa, alphad, DE)
339
+ if A is not None:
340
+ aa, z = A
341
+ if aa == 1:
342
+ beta = -(a*derivation(z, DE).as_poly(t1) +
343
+ b*z.as_poly(t1)).LC()/(z.as_expr()*a.LC())
344
+ betaa, betad = frac_in(beta, DE.t)
345
+ from .prde import limited_integrate
346
+ try:
347
+ (za, zd), m = limited_integrate(betaa, betad,
348
+ [(etaa, etad)], DE)
349
+ except NonElementaryIntegralException:
350
+ pass
351
+ else:
352
+ if len(m) != 1:
353
+ raise ValueError("Length of m should be 1")
354
+ n = max(n, m[0].as_expr())
355
+
356
+ elif case == 'exp':
357
+ from .prde import parametric_log_deriv
358
+
359
+ n = max(0, dc - max(db, da))
360
+ if da == db:
361
+ etaa, etad = frac_in(DE.d.quo(Poly(DE.t, DE.t)), DE.T[DE.level - 1])
362
+ with DecrementLevel(DE):
363
+ alphaa, alphad = frac_in(alpha, DE.t)
364
+ A = parametric_log_deriv(alphaa, alphad, etaa, etad, DE)
365
+ if A is not None:
366
+ # if alpha == m*Dt/t + Dz/z for z in k* and m in ZZ:
367
+ # n = max(n, m)
368
+ a, m, z = A
369
+ if a == 1:
370
+ n = max(n, m)
371
+
372
+ elif case in ('tan', 'other_nonlinear'):
373
+ delta = DE.d.degree(DE.t)
374
+ lam = DE.d.LC()
375
+ alpha = cancel(alpha/lam)
376
+ n = max(0, dc - max(da + delta - 1, db))
377
+ if db == da + delta - 1 and alpha.is_Integer:
378
+ n = max(0, alpha, dc - db)
379
+
380
+ else:
381
+ raise ValueError("case must be one of {'exp', 'tan', 'primitive', "
382
+ "'other_nonlinear', 'base'}, not %s." % case)
383
+
384
+ return n
385
+
386
+
387
+ def spde(a, b, c, n, DE):
388
+ """
389
+ Rothstein's Special Polynomial Differential Equation algorithm.
390
+
391
+ Explanation
392
+ ===========
393
+
394
+ Given a derivation D on k[t], an integer n and ``a``,``b``,``c`` in k[t] with
395
+ ``a != 0``, either raise NonElementaryIntegralException, in which case the
396
+ equation a*Dq + b*q == c has no solution of degree at most ``n`` in
397
+ k[t], or return the tuple (B, C, m, alpha, beta) such that B, C,
398
+ alpha, beta in k[t], m in ZZ, and any solution q in k[t] of degree
399
+ at most n of a*Dq + b*q == c must be of the form
400
+ q == alpha*h + beta, where h in k[t], deg(h) <= m, and Dh + B*h == C.
401
+
402
+ This constitutes step 4 of the outline given in the rde.py docstring.
403
+ """
404
+ zero = Poly(0, DE.t)
405
+
406
+ alpha = Poly(1, DE.t)
407
+ beta = Poly(0, DE.t)
408
+
409
+ while True:
410
+ if c.is_zero:
411
+ return (zero, zero, 0, zero, beta) # -1 is more to the point
412
+ if (n < 0) is True:
413
+ raise NonElementaryIntegralException
414
+
415
+ g = a.gcd(b)
416
+ if not c.rem(g).is_zero: # g does not divide c
417
+ raise NonElementaryIntegralException
418
+
419
+ a, b, c = a.quo(g), b.quo(g), c.quo(g)
420
+
421
+ if a.degree(DE.t) == 0:
422
+ b = b.to_field().quo(a)
423
+ c = c.to_field().quo(a)
424
+ return (b, c, n, alpha, beta)
425
+
426
+ r, z = gcdex_diophantine(b, a, c)
427
+ b += derivation(a, DE)
428
+ c = z - derivation(r, DE)
429
+ n -= a.degree(DE.t)
430
+
431
+ beta += alpha * r
432
+ alpha *= a
433
+
434
+ def no_cancel_b_large(b, c, n, DE):
435
+ """
436
+ Poly Risch Differential Equation - No cancellation: deg(b) large enough.
437
+
438
+ Explanation
439
+ ===========
440
+
441
+ Given a derivation D on k[t], ``n`` either an integer or +oo, and ``b``,``c``
442
+ in k[t] with ``b != 0`` and either D == d/dt or
443
+ deg(b) > max(0, deg(D) - 1), either raise NonElementaryIntegralException, in
444
+ which case the equation ``Dq + b*q == c`` has no solution of degree at
445
+ most n in k[t], or a solution q in k[t] of this equation with
446
+ ``deg(q) < n``.
447
+ """
448
+ q = Poly(0, DE.t)
449
+
450
+ while not c.is_zero:
451
+ m = c.degree(DE.t) - b.degree(DE.t)
452
+ if not 0 <= m <= n: # n < 0 or m < 0 or m > n
453
+ raise NonElementaryIntegralException
454
+
455
+ p = Poly(c.as_poly(DE.t).LC()/b.as_poly(DE.t).LC()*DE.t**m, DE.t,
456
+ expand=False)
457
+ q = q + p
458
+ n = m - 1
459
+ c = c - derivation(p, DE) - b*p
460
+
461
+ return q
462
+
463
+
464
+ def no_cancel_b_small(b, c, n, DE):
465
+ """
466
+ Poly Risch Differential Equation - No cancellation: deg(b) small enough.
467
+
468
+ Explanation
469
+ ===========
470
+
471
+ Given a derivation D on k[t], ``n`` either an integer or +oo, and ``b``,``c``
472
+ in k[t] with deg(b) < deg(D) - 1 and either D == d/dt or
473
+ deg(D) >= 2, either raise NonElementaryIntegralException, in which case the
474
+ equation Dq + b*q == c has no solution of degree at most n in k[t],
475
+ or a solution q in k[t] of this equation with deg(q) <= n, or the
476
+ tuple (h, b0, c0) such that h in k[t], b0, c0, in k, and for any
477
+ solution q in k[t] of degree at most n of Dq + bq == c, y == q - h
478
+ is a solution in k of Dy + b0*y == c0.
479
+ """
480
+ q = Poly(0, DE.t)
481
+
482
+ while not c.is_zero:
483
+ if n == 0:
484
+ m = 0
485
+ else:
486
+ m = c.degree(DE.t) - DE.d.degree(DE.t) + 1
487
+
488
+ if not 0 <= m <= n: # n < 0 or m < 0 or m > n
489
+ raise NonElementaryIntegralException
490
+
491
+ if m > 0:
492
+ p = Poly(c.as_poly(DE.t).LC()/(m*DE.d.as_poly(DE.t).LC())*DE.t**m,
493
+ DE.t, expand=False)
494
+ else:
495
+ if b.degree(DE.t) != c.degree(DE.t):
496
+ raise NonElementaryIntegralException
497
+ if b.degree(DE.t) == 0:
498
+ return (q, b.as_poly(DE.T[DE.level - 1]),
499
+ c.as_poly(DE.T[DE.level - 1]))
500
+ p = Poly(c.as_poly(DE.t).LC()/b.as_poly(DE.t).LC(), DE.t,
501
+ expand=False)
502
+
503
+ q = q + p
504
+ n = m - 1
505
+ c = c - derivation(p, DE) - b*p
506
+
507
+ return q
508
+
509
+
510
+ # TODO: better name for this function
511
+ def no_cancel_equal(b, c, n, DE):
512
+ """
513
+ Poly Risch Differential Equation - No cancellation: deg(b) == deg(D) - 1
514
+
515
+ Explanation
516
+ ===========
517
+
518
+ Given a derivation D on k[t] with deg(D) >= 2, n either an integer
519
+ or +oo, and b, c in k[t] with deg(b) == deg(D) - 1, either raise
520
+ NonElementaryIntegralException, in which case the equation Dq + b*q == c has
521
+ no solution of degree at most n in k[t], or a solution q in k[t] of
522
+ this equation with deg(q) <= n, or the tuple (h, m, C) such that h
523
+ in k[t], m in ZZ, and C in k[t], and for any solution q in k[t] of
524
+ degree at most n of Dq + b*q == c, y == q - h is a solution in k[t]
525
+ of degree at most m of Dy + b*y == C.
526
+ """
527
+ q = Poly(0, DE.t)
528
+ lc = cancel(-b.as_poly(DE.t).LC()/DE.d.as_poly(DE.t).LC())
529
+ if lc.is_Integer and lc.is_positive:
530
+ M = lc
531
+ else:
532
+ M = -1
533
+
534
+ while not c.is_zero:
535
+ m = max(M, c.degree(DE.t) - DE.d.degree(DE.t) + 1)
536
+
537
+ if not 0 <= m <= n: # n < 0 or m < 0 or m > n
538
+ raise NonElementaryIntegralException
539
+
540
+ u = cancel(m*DE.d.as_poly(DE.t).LC() + b.as_poly(DE.t).LC())
541
+ if u.is_zero:
542
+ return (q, m, c)
543
+ if m > 0:
544
+ p = Poly(c.as_poly(DE.t).LC()/u*DE.t**m, DE.t, expand=False)
545
+ else:
546
+ if c.degree(DE.t) != DE.d.degree(DE.t) - 1:
547
+ raise NonElementaryIntegralException
548
+ else:
549
+ p = c.as_poly(DE.t).LC()/b.as_poly(DE.t).LC()
550
+
551
+ q = q + p
552
+ n = m - 1
553
+ c = c - derivation(p, DE) - b*p
554
+
555
+ return q
556
+
557
+
558
+ def cancel_primitive(b, c, n, DE):
559
+ """
560
+ Poly Risch Differential Equation - Cancellation: Primitive case.
561
+
562
+ Explanation
563
+ ===========
564
+
565
+ Given a derivation D on k[t], n either an integer or +oo, ``b`` in k, and
566
+ ``c`` in k[t] with Dt in k and ``b != 0``, either raise
567
+ NonElementaryIntegralException, in which case the equation Dq + b*q == c
568
+ has no solution of degree at most n in k[t], or a solution q in k[t] of
569
+ this equation with deg(q) <= n.
570
+ """
571
+ # Delayed imports
572
+ from .prde import is_log_deriv_k_t_radical_in_field
573
+ with DecrementLevel(DE):
574
+ ba, bd = frac_in(b, DE.t)
575
+ A = is_log_deriv_k_t_radical_in_field(ba, bd, DE)
576
+ if A is not None:
577
+ n, z = A
578
+ if n == 1: # b == Dz/z
579
+ raise NotImplementedError("is_deriv_in_field() is required to "
580
+ " solve this problem.")
581
+ # if z*c == Dp for p in k[t] and deg(p) <= n:
582
+ # return p/z
583
+ # else:
584
+ # raise NonElementaryIntegralException
585
+
586
+ if c.is_zero:
587
+ return c # return 0
588
+
589
+ if n < c.degree(DE.t):
590
+ raise NonElementaryIntegralException
591
+
592
+ q = Poly(0, DE.t)
593
+ while not c.is_zero:
594
+ m = c.degree(DE.t)
595
+ if n < m:
596
+ raise NonElementaryIntegralException
597
+ with DecrementLevel(DE):
598
+ a2a, a2d = frac_in(c.LC(), DE.t)
599
+ sa, sd = rischDE(ba, bd, a2a, a2d, DE)
600
+ stm = Poly(sa.as_expr()/sd.as_expr()*DE.t**m, DE.t, expand=False)
601
+ q += stm
602
+ n = m - 1
603
+ c -= b*stm + derivation(stm, DE)
604
+
605
+ return q
606
+
607
+
608
+ def cancel_exp(b, c, n, DE):
609
+ """
610
+ Poly Risch Differential Equation - Cancellation: Hyperexponential case.
611
+
612
+ Explanation
613
+ ===========
614
+
615
+ Given a derivation D on k[t], n either an integer or +oo, ``b`` in k, and
616
+ ``c`` in k[t] with Dt/t in k and ``b != 0``, either raise
617
+ NonElementaryIntegralException, in which case the equation Dq + b*q == c
618
+ has no solution of degree at most n in k[t], or a solution q in k[t] of
619
+ this equation with deg(q) <= n.
620
+ """
621
+ from .prde import parametric_log_deriv
622
+ eta = DE.d.quo(Poly(DE.t, DE.t)).as_expr()
623
+
624
+ with DecrementLevel(DE):
625
+ etaa, etad = frac_in(eta, DE.t)
626
+ ba, bd = frac_in(b, DE.t)
627
+ A = parametric_log_deriv(ba, bd, etaa, etad, DE)
628
+ if A is not None:
629
+ a, m, z = A
630
+ if a == 1:
631
+ raise NotImplementedError("is_deriv_in_field() is required to "
632
+ "solve this problem.")
633
+ # if c*z*t**m == Dp for p in k<t> and q = p/(z*t**m) in k[t] and
634
+ # deg(q) <= n:
635
+ # return q
636
+ # else:
637
+ # raise NonElementaryIntegralException
638
+
639
+ if c.is_zero:
640
+ return c # return 0
641
+
642
+ if n < c.degree(DE.t):
643
+ raise NonElementaryIntegralException
644
+
645
+ q = Poly(0, DE.t)
646
+ while not c.is_zero:
647
+ m = c.degree(DE.t)
648
+ if n < m:
649
+ raise NonElementaryIntegralException
650
+ # a1 = b + m*Dt/t
651
+ a1 = b.as_expr()
652
+ with DecrementLevel(DE):
653
+ # TODO: Write a dummy function that does this idiom
654
+ a1a, a1d = frac_in(a1, DE.t)
655
+ a1a = a1a*etad + etaa*a1d*Poly(m, DE.t)
656
+ a1d = a1d*etad
657
+
658
+ a2a, a2d = frac_in(c.LC(), DE.t)
659
+
660
+ sa, sd = rischDE(a1a, a1d, a2a, a2d, DE)
661
+ stm = Poly(sa.as_expr()/sd.as_expr()*DE.t**m, DE.t, expand=False)
662
+ q += stm
663
+ n = m - 1
664
+ c -= b*stm + derivation(stm, DE) # deg(c) becomes smaller
665
+ return q
666
+
667
+
668
+ def solve_poly_rde(b, cQ, n, DE, parametric=False):
669
+ """
670
+ Solve a Polynomial Risch Differential Equation with degree bound ``n``.
671
+
672
+ This constitutes step 4 of the outline given in the rde.py docstring.
673
+
674
+ For parametric=False, cQ is c, a Poly; for parametric=True, cQ is Q ==
675
+ [q1, ..., qm], a list of Polys.
676
+ """
677
+ # No cancellation
678
+ if not b.is_zero and (DE.case == 'base' or
679
+ b.degree(DE.t) > max(0, DE.d.degree(DE.t) - 1)):
680
+
681
+ if parametric:
682
+ # Delayed imports
683
+ from .prde import prde_no_cancel_b_large
684
+ return prde_no_cancel_b_large(b, cQ, n, DE)
685
+ return no_cancel_b_large(b, cQ, n, DE)
686
+
687
+ elif (b.is_zero or b.degree(DE.t) < DE.d.degree(DE.t) - 1) and \
688
+ (DE.case == 'base' or DE.d.degree(DE.t) >= 2):
689
+
690
+ if parametric:
691
+ from .prde import prde_no_cancel_b_small
692
+ return prde_no_cancel_b_small(b, cQ, n, DE)
693
+
694
+ R = no_cancel_b_small(b, cQ, n, DE)
695
+
696
+ if isinstance(R, Poly):
697
+ return R
698
+ else:
699
+ # XXX: Might k be a field? (pg. 209)
700
+ h, b0, c0 = R
701
+ with DecrementLevel(DE):
702
+ b0, c0 = b0.as_poly(DE.t), c0.as_poly(DE.t)
703
+ if b0 is None: # See above comment
704
+ raise ValueError("b0 should be a non-Null value")
705
+ if c0 is None:
706
+ raise ValueError("c0 should be a non-Null value")
707
+ y = solve_poly_rde(b0, c0, n, DE).as_poly(DE.t)
708
+ return h + y
709
+
710
+ elif DE.d.degree(DE.t) >= 2 and b.degree(DE.t) == DE.d.degree(DE.t) - 1 and \
711
+ n > -b.as_poly(DE.t).LC()/DE.d.as_poly(DE.t).LC():
712
+
713
+ # TODO: Is this check necessary, and if so, what should it do if it fails?
714
+ # b comes from the first element returned from spde()
715
+ if not b.as_poly(DE.t).LC().is_number:
716
+ raise TypeError("Result should be a number")
717
+
718
+ if parametric:
719
+ raise NotImplementedError("prde_no_cancel_b_equal() is not yet "
720
+ "implemented.")
721
+
722
+ R = no_cancel_equal(b, cQ, n, DE)
723
+
724
+ if isinstance(R, Poly):
725
+ return R
726
+ else:
727
+ h, m, C = R
728
+ # XXX: Or should it be rischDE()?
729
+ y = solve_poly_rde(b, C, m, DE)
730
+ return h + y
731
+
732
+ else:
733
+ # Cancellation
734
+ if b.is_zero:
735
+ raise NotImplementedError("Remaining cases for Poly (P)RDE are "
736
+ "not yet implemented (is_deriv_in_field() required).")
737
+ else:
738
+ if DE.case == 'exp':
739
+ if parametric:
740
+ raise NotImplementedError("Parametric RDE cancellation "
741
+ "hyperexponential case is not yet implemented.")
742
+ return cancel_exp(b, cQ, n, DE)
743
+
744
+ elif DE.case == 'primitive':
745
+ if parametric:
746
+ raise NotImplementedError("Parametric RDE cancellation "
747
+ "primitive case is not yet implemented.")
748
+ return cancel_primitive(b, cQ, n, DE)
749
+
750
+ else:
751
+ raise NotImplementedError("Other Poly (P)RDE cancellation "
752
+ "cases are not yet implemented (%s)." % DE.case)
753
+
754
+ if parametric:
755
+ raise NotImplementedError("Remaining cases for Poly PRDE not yet "
756
+ "implemented.")
757
+ raise NotImplementedError("Remaining cases for Poly RDE not yet "
758
+ "implemented.")
759
+
760
+
761
+ def rischDE(fa, fd, ga, gd, DE):
762
+ """
763
+ Solve a Risch Differential Equation: Dy + f*y == g.
764
+
765
+ Explanation
766
+ ===========
767
+
768
+ See the outline in the docstring of rde.py for more information
769
+ about the procedure used. Either raise NonElementaryIntegralException, in
770
+ which case there is no solution y in the given differential field,
771
+ or return y in k(t) satisfying Dy + f*y == g, or raise
772
+ NotImplementedError, in which case, the algorithms necessary to
773
+ solve the given Risch Differential Equation have not yet been
774
+ implemented.
775
+ """
776
+ _, (fa, fd) = weak_normalizer(fa, fd, DE)
777
+ a, (ba, bd), (ca, cd), hn = normal_denom(fa, fd, ga, gd, DE)
778
+ A, B, C, hs = special_denom(a, ba, bd, ca, cd, DE)
779
+ try:
780
+ # Until this is fully implemented, use oo. Note that this will almost
781
+ # certainly cause non-termination in spde() (unless A == 1), and
782
+ # *might* lead to non-termination in the next step for a nonelementary
783
+ # integral (I don't know for certain yet). Fortunately, spde() is
784
+ # currently written recursively, so this will just give
785
+ # RuntimeError: maximum recursion depth exceeded.
786
+ n = bound_degree(A, B, C, DE)
787
+ except NotImplementedError:
788
+ # Useful for debugging:
789
+ # import warnings
790
+ # warnings.warn("rischDE: Proceeding with n = oo; may cause "
791
+ # "non-termination.")
792
+ n = oo
793
+
794
+ B, C, m, alpha, beta = spde(A, B, C, n, DE)
795
+ if C.is_zero:
796
+ y = C
797
+ else:
798
+ y = solve_poly_rde(B, C, m, DE)
799
+
800
+ return (alpha*y + beta, hn*hs)
venv/lib/python3.10/site-packages/sympy/integrals/risch.py ADDED
@@ -0,0 +1,1858 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ """
2
+ The Risch Algorithm for transcendental function integration.
3
+
4
+ The core algorithms for the Risch algorithm are here. The subproblem
5
+ algorithms are in the rde.py and prde.py files for the Risch
6
+ Differential Equation solver and the parametric problems solvers,
7
+ respectively. All important information concerning the differential extension
8
+ for an integrand is stored in a DifferentialExtension object, which in the code
9
+ is usually called DE. Throughout the code and Inside the DifferentialExtension
10
+ object, the conventions/attribute names are that the base domain is QQ and each
11
+ differential extension is x, t0, t1, ..., tn-1 = DE.t. DE.x is the variable of
12
+ integration (Dx == 1), DE.D is a list of the derivatives of
13
+ x, t1, t2, ..., tn-1 = t, DE.T is the list [x, t1, t2, ..., tn-1], DE.t is the
14
+ outer-most variable of the differential extension at the given level (the level
15
+ can be adjusted using DE.increment_level() and DE.decrement_level()),
16
+ k is the field C(x, t0, ..., tn-2), where C is the constant field. The
17
+ numerator of a fraction is denoted by a and the denominator by
18
+ d. If the fraction is named f, fa == numer(f) and fd == denom(f).
19
+ Fractions are returned as tuples (fa, fd). DE.d and DE.t are used to
20
+ represent the topmost derivation and extension variable, respectively.
21
+ The docstring of a function signifies whether an argument is in k[t], in
22
+ which case it will just return a Poly in t, or in k(t), in which case it
23
+ will return the fraction (fa, fd). Other variable names probably come
24
+ from the names used in Bronstein's book.
25
+ """
26
+ from types import GeneratorType
27
+ from functools import reduce
28
+
29
+ from sympy.core.function import Lambda
30
+ from sympy.core.mul import Mul
31
+ from sympy.core.numbers import ilcm, I, oo
32
+ from sympy.core.power import Pow
33
+ from sympy.core.relational import Ne
34
+ from sympy.core.singleton import S
35
+ from sympy.core.sorting import ordered, default_sort_key
36
+ from sympy.core.symbol import Dummy, Symbol
37
+ from sympy.functions.elementary.exponential import log, exp
38
+ from sympy.functions.elementary.hyperbolic import (cosh, coth, sinh,
39
+ tanh)
40
+ from sympy.functions.elementary.piecewise import Piecewise
41
+ from sympy.functions.elementary.trigonometric import (atan, sin, cos,
42
+ tan, acot, cot, asin, acos)
43
+ from .integrals import integrate, Integral
44
+ from .heurisch import _symbols
45
+ from sympy.polys.polyerrors import DomainError, PolynomialError
46
+ from sympy.polys.polytools import (real_roots, cancel, Poly, gcd,
47
+ reduced)
48
+ from sympy.polys.rootoftools import RootSum
49
+ from sympy.utilities.iterables import numbered_symbols
50
+
51
+
52
+ def integer_powers(exprs):
53
+ """
54
+ Rewrites a list of expressions as integer multiples of each other.
55
+
56
+ Explanation
57
+ ===========
58
+
59
+ For example, if you have [x, x/2, x**2 + 1, 2*x/3], then you can rewrite
60
+ this as [(x/6) * 6, (x/6) * 3, (x**2 + 1) * 1, (x/6) * 4]. This is useful
61
+ in the Risch integration algorithm, where we must write exp(x) + exp(x/2)
62
+ as (exp(x/2))**2 + exp(x/2), but not as exp(x) + sqrt(exp(x)) (this is
63
+ because only the transcendental case is implemented and we therefore cannot
64
+ integrate algebraic extensions). The integer multiples returned by this
65
+ function for each term are the smallest possible (their content equals 1).
66
+
67
+ Returns a list of tuples where the first element is the base term and the
68
+ second element is a list of `(item, factor)` terms, where `factor` is the
69
+ integer multiplicative factor that must multiply the base term to obtain
70
+ the original item.
71
+
72
+ The easiest way to understand this is to look at an example:
73
+
74
+ >>> from sympy.abc import x
75
+ >>> from sympy.integrals.risch import integer_powers
76
+ >>> integer_powers([x, x/2, x**2 + 1, 2*x/3])
77
+ [(x/6, [(x, 6), (x/2, 3), (2*x/3, 4)]), (x**2 + 1, [(x**2 + 1, 1)])]
78
+
79
+ We can see how this relates to the example at the beginning of the
80
+ docstring. It chose x/6 as the first base term. Then, x can be written as
81
+ (x/2) * 2, so we get (0, 2), and so on. Now only element (x**2 + 1)
82
+ remains, and there are no other terms that can be written as a rational
83
+ multiple of that, so we get that it can be written as (x**2 + 1) * 1.
84
+
85
+ """
86
+ # Here is the strategy:
87
+
88
+ # First, go through each term and determine if it can be rewritten as a
89
+ # rational multiple of any of the terms gathered so far.
90
+ # cancel(a/b).is_Rational is sufficient for this. If it is a multiple, we
91
+ # add its multiple to the dictionary.
92
+
93
+ terms = {}
94
+ for term in exprs:
95
+ for trm, trm_list in terms.items():
96
+ a = cancel(term/trm)
97
+ if a.is_Rational:
98
+ trm_list.append((term, a))
99
+ break
100
+ else:
101
+ terms[term] = [(term, S.One)]
102
+
103
+ # After we have done this, we have all the like terms together, so we just
104
+ # need to find a common denominator so that we can get the base term and
105
+ # integer multiples such that each term can be written as an integer
106
+ # multiple of the base term, and the content of the integers is 1.
107
+
108
+ newterms = {}
109
+ for term, term_list in terms.items():
110
+ common_denom = reduce(ilcm, [i.as_numer_denom()[1] for _, i in
111
+ term_list])
112
+ newterm = term/common_denom
113
+ newmults = [(i, j*common_denom) for i, j in term_list]
114
+ newterms[newterm] = newmults
115
+
116
+ return sorted(iter(newterms.items()), key=lambda item: item[0].sort_key())
117
+
118
+
119
+ class DifferentialExtension:
120
+ """
121
+ A container for all the information relating to a differential extension.
122
+
123
+ Explanation
124
+ ===========
125
+
126
+ The attributes of this object are (see also the docstring of __init__):
127
+
128
+ - f: The original (Expr) integrand.
129
+ - x: The variable of integration.
130
+ - T: List of variables in the extension.
131
+ - D: List of derivations in the extension; corresponds to the elements of T.
132
+ - fa: Poly of the numerator of the integrand.
133
+ - fd: Poly of the denominator of the integrand.
134
+ - Tfuncs: Lambda() representations of each element of T (except for x).
135
+ For back-substitution after integration.
136
+ - backsubs: A (possibly empty) list of further substitutions to be made on
137
+ the final integral to make it look more like the integrand.
138
+ - exts:
139
+ - extargs:
140
+ - cases: List of string representations of the cases of T.
141
+ - t: The top level extension variable, as defined by the current level
142
+ (see level below).
143
+ - d: The top level extension derivation, as defined by the current
144
+ derivation (see level below).
145
+ - case: The string representation of the case of self.d.
146
+ (Note that self.T and self.D will always contain the complete extension,
147
+ regardless of the level. Therefore, you should ALWAYS use DE.t and DE.d
148
+ instead of DE.T[-1] and DE.D[-1]. If you want to have a list of the
149
+ derivations or variables only up to the current level, use
150
+ DE.D[:len(DE.D) + DE.level + 1] and DE.T[:len(DE.T) + DE.level + 1]. Note
151
+ that, in particular, the derivation() function does this.)
152
+
153
+ The following are also attributes, but will probably not be useful other
154
+ than in internal use:
155
+ - newf: Expr form of fa/fd.
156
+ - level: The number (between -1 and -len(self.T)) such that
157
+ self.T[self.level] == self.t and self.D[self.level] == self.d.
158
+ Use the methods self.increment_level() and self.decrement_level() to change
159
+ the current level.
160
+ """
161
+ # __slots__ is defined mainly so we can iterate over all the attributes
162
+ # of the class easily (the memory use doesn't matter too much, since we
163
+ # only create one DifferentialExtension per integration). Also, it's nice
164
+ # to have a safeguard when debugging.
165
+ __slots__ = ('f', 'x', 'T', 'D', 'fa', 'fd', 'Tfuncs', 'backsubs',
166
+ 'exts', 'extargs', 'cases', 'case', 't', 'd', 'newf', 'level',
167
+ 'ts', 'dummy')
168
+
169
+ def __init__(self, f=None, x=None, handle_first='log', dummy=False, extension=None, rewrite_complex=None):
170
+ """
171
+ Tries to build a transcendental extension tower from ``f`` with respect to ``x``.
172
+
173
+ Explanation
174
+ ===========
175
+
176
+ If it is successful, creates a DifferentialExtension object with, among
177
+ others, the attributes fa, fd, D, T, Tfuncs, and backsubs such that
178
+ fa and fd are Polys in T[-1] with rational coefficients in T[:-1],
179
+ fa/fd == f, and D[i] is a Poly in T[i] with rational coefficients in
180
+ T[:i] representing the derivative of T[i] for each i from 1 to len(T).
181
+ Tfuncs is a list of Lambda objects for back replacing the functions
182
+ after integrating. Lambda() is only used (instead of lambda) to make
183
+ them easier to test and debug. Note that Tfuncs corresponds to the
184
+ elements of T, except for T[0] == x, but they should be back-substituted
185
+ in reverse order. backsubs is a (possibly empty) back-substitution list
186
+ that should be applied on the completed integral to make it look more
187
+ like the original integrand.
188
+
189
+ If it is unsuccessful, it raises NotImplementedError.
190
+
191
+ You can also create an object by manually setting the attributes as a
192
+ dictionary to the extension keyword argument. You must include at least
193
+ D. Warning, any attribute that is not given will be set to None. The
194
+ attributes T, t, d, cases, case, x, and level are set automatically and
195
+ do not need to be given. The functions in the Risch Algorithm will NOT
196
+ check to see if an attribute is None before using it. This also does not
197
+ check to see if the extension is valid (non-algebraic) or even if it is
198
+ self-consistent. Therefore, this should only be used for
199
+ testing/debugging purposes.
200
+ """
201
+ # XXX: If you need to debug this function, set the break point here
202
+
203
+ if extension:
204
+ if 'D' not in extension:
205
+ raise ValueError("At least the key D must be included with "
206
+ "the extension flag to DifferentialExtension.")
207
+ for attr in extension:
208
+ setattr(self, attr, extension[attr])
209
+
210
+ self._auto_attrs()
211
+
212
+ return
213
+ elif f is None or x is None:
214
+ raise ValueError("Either both f and x or a manual extension must "
215
+ "be given.")
216
+
217
+ if handle_first not in ('log', 'exp'):
218
+ raise ValueError("handle_first must be 'log' or 'exp', not %s." %
219
+ str(handle_first))
220
+
221
+ # f will be the original function, self.f might change if we reset
222
+ # (e.g., we pull out a constant from an exponential)
223
+ self.f = f
224
+ self.x = x
225
+ # setting the default value 'dummy'
226
+ self.dummy = dummy
227
+ self.reset()
228
+ exp_new_extension, log_new_extension = True, True
229
+
230
+ # case of 'automatic' choosing
231
+ if rewrite_complex is None:
232
+ rewrite_complex = I in self.f.atoms()
233
+
234
+ if rewrite_complex:
235
+ rewritables = {
236
+ (sin, cos, cot, tan, sinh, cosh, coth, tanh): exp,
237
+ (asin, acos, acot, atan): log,
238
+ }
239
+ # rewrite the trigonometric components
240
+ for candidates, rule in rewritables.items():
241
+ self.newf = self.newf.rewrite(candidates, rule)
242
+ self.newf = cancel(self.newf)
243
+ else:
244
+ if any(i.has(x) for i in self.f.atoms(sin, cos, tan, atan, asin, acos)):
245
+ raise NotImplementedError("Trigonometric extensions are not "
246
+ "supported (yet!)")
247
+
248
+ exps = set()
249
+ pows = set()
250
+ numpows = set()
251
+ sympows = set()
252
+ logs = set()
253
+ symlogs = set()
254
+
255
+ while True:
256
+ if self.newf.is_rational_function(*self.T):
257
+ break
258
+
259
+ if not exp_new_extension and not log_new_extension:
260
+ # We couldn't find a new extension on the last pass, so I guess
261
+ # we can't do it.
262
+ raise NotImplementedError("Couldn't find an elementary "
263
+ "transcendental extension for %s. Try using a " % str(f) +
264
+ "manual extension with the extension flag.")
265
+
266
+ exps, pows, numpows, sympows, log_new_extension = \
267
+ self._rewrite_exps_pows(exps, pows, numpows, sympows, log_new_extension)
268
+
269
+ logs, symlogs = self._rewrite_logs(logs, symlogs)
270
+
271
+ if handle_first == 'exp' or not log_new_extension:
272
+ exp_new_extension = self._exp_part(exps)
273
+ if exp_new_extension is None:
274
+ # reset and restart
275
+ self.f = self.newf
276
+ self.reset()
277
+ exp_new_extension = True
278
+ continue
279
+
280
+ if handle_first == 'log' or not exp_new_extension:
281
+ log_new_extension = self._log_part(logs)
282
+
283
+ self.fa, self.fd = frac_in(self.newf, self.t)
284
+ self._auto_attrs()
285
+
286
+ return
287
+
288
+ def __getattr__(self, attr):
289
+ # Avoid AttributeErrors when debugging
290
+ if attr not in self.__slots__:
291
+ raise AttributeError("%s has no attribute %s" % (repr(self), repr(attr)))
292
+ return None
293
+
294
+ def _rewrite_exps_pows(self, exps, pows, numpows,
295
+ sympows, log_new_extension):
296
+ """
297
+ Rewrite exps/pows for better processing.
298
+ """
299
+ from .prde import is_deriv_k
300
+
301
+ # Pre-preparsing.
302
+ #################
303
+ # Get all exp arguments, so we can avoid ahead of time doing
304
+ # something like t1 = exp(x), t2 = exp(x/2) == sqrt(t1).
305
+
306
+ # Things like sqrt(exp(x)) do not automatically simplify to
307
+ # exp(x/2), so they will be viewed as algebraic. The easiest way
308
+ # to handle this is to convert all instances of exp(a)**Rational
309
+ # to exp(Rational*a) before doing anything else. Note that the
310
+ # _exp_part code can generate terms of this form, so we do need to
311
+ # do this at each pass (or else modify it to not do that).
312
+
313
+ ratpows = [i for i in self.newf.atoms(Pow)
314
+ if (isinstance(i.base, exp) and i.exp.is_Rational)]
315
+
316
+ ratpows_repl = [
317
+ (i, i.base.base**(i.exp*i.base.exp)) for i in ratpows]
318
+ self.backsubs += [(j, i) for i, j in ratpows_repl]
319
+ self.newf = self.newf.xreplace(dict(ratpows_repl))
320
+
321
+ # To make the process deterministic, the args are sorted
322
+ # so that functions with smaller op-counts are processed first.
323
+ # Ties are broken with the default_sort_key.
324
+
325
+ # XXX Although the method is deterministic no additional work
326
+ # has been done to guarantee that the simplest solution is
327
+ # returned and that it would be affected be using different
328
+ # variables. Though it is possible that this is the case
329
+ # one should know that it has not been done intentionally, so
330
+ # further improvements may be possible.
331
+
332
+ # TODO: This probably doesn't need to be completely recomputed at
333
+ # each pass.
334
+ exps = update_sets(exps, self.newf.atoms(exp),
335
+ lambda i: i.exp.is_rational_function(*self.T) and
336
+ i.exp.has(*self.T))
337
+ pows = update_sets(pows, self.newf.atoms(Pow),
338
+ lambda i: i.exp.is_rational_function(*self.T) and
339
+ i.exp.has(*self.T))
340
+ numpows = update_sets(numpows, set(pows),
341
+ lambda i: not i.base.has(*self.T))
342
+ sympows = update_sets(sympows, set(pows) - set(numpows),
343
+ lambda i: i.base.is_rational_function(*self.T) and
344
+ not i.exp.is_Integer)
345
+
346
+ # The easiest way to deal with non-base E powers is to convert them
347
+ # into base E, integrate, and then convert back.
348
+ for i in ordered(pows):
349
+ old = i
350
+ new = exp(i.exp*log(i.base))
351
+ # If exp is ever changed to automatically reduce exp(x*log(2))
352
+ # to 2**x, then this will break. The solution is to not change
353
+ # exp to do that :)
354
+ if i in sympows:
355
+ if i.exp.is_Rational:
356
+ raise NotImplementedError("Algebraic extensions are "
357
+ "not supported (%s)." % str(i))
358
+ # We can add a**b only if log(a) in the extension, because
359
+ # a**b == exp(b*log(a)).
360
+ basea, based = frac_in(i.base, self.t)
361
+ A = is_deriv_k(basea, based, self)
362
+ if A is None:
363
+ # Nonelementary monomial (so far)
364
+
365
+ # TODO: Would there ever be any benefit from just
366
+ # adding log(base) as a new monomial?
367
+ # ANSWER: Yes, otherwise we can't integrate x**x (or
368
+ # rather prove that it has no elementary integral)
369
+ # without first manually rewriting it as exp(x*log(x))
370
+ self.newf = self.newf.xreplace({old: new})
371
+ self.backsubs += [(new, old)]
372
+ log_new_extension = self._log_part([log(i.base)])
373
+ exps = update_sets(exps, self.newf.atoms(exp), lambda i:
374
+ i.exp.is_rational_function(*self.T) and i.exp.has(*self.T))
375
+ continue
376
+ ans, u, const = A
377
+ newterm = exp(i.exp*(log(const) + u))
378
+ # Under the current implementation, exp kills terms
379
+ # only if they are of the form a*log(x), where a is a
380
+ # Number. This case should have already been killed by the
381
+ # above tests. Again, if this changes to kill more than
382
+ # that, this will break, which maybe is a sign that you
383
+ # shouldn't be changing that. Actually, if anything, this
384
+ # auto-simplification should be removed. See
385
+ # https://groups.google.com/group/sympy/browse_thread/thread/a61d48235f16867f
386
+
387
+ self.newf = self.newf.xreplace({i: newterm})
388
+
389
+ elif i not in numpows:
390
+ continue
391
+ else:
392
+ # i in numpows
393
+ newterm = new
394
+ # TODO: Just put it in self.Tfuncs
395
+ self.backsubs.append((new, old))
396
+ self.newf = self.newf.xreplace({old: newterm})
397
+ exps.append(newterm)
398
+
399
+ return exps, pows, numpows, sympows, log_new_extension
400
+
401
+ def _rewrite_logs(self, logs, symlogs):
402
+ """
403
+ Rewrite logs for better processing.
404
+ """
405
+ atoms = self.newf.atoms(log)
406
+ logs = update_sets(logs, atoms,
407
+ lambda i: i.args[0].is_rational_function(*self.T) and
408
+ i.args[0].has(*self.T))
409
+ symlogs = update_sets(symlogs, atoms,
410
+ lambda i: i.has(*self.T) and i.args[0].is_Pow and
411
+ i.args[0].base.is_rational_function(*self.T) and
412
+ not i.args[0].exp.is_Integer)
413
+
414
+ # We can handle things like log(x**y) by converting it to y*log(x)
415
+ # This will fix not only symbolic exponents of the argument, but any
416
+ # non-Integer exponent, like log(sqrt(x)). The exponent can also
417
+ # depend on x, like log(x**x).
418
+ for i in ordered(symlogs):
419
+ # Unlike in the exponential case above, we do not ever
420
+ # potentially add new monomials (above we had to add log(a)).
421
+ # Therefore, there is no need to run any is_deriv functions
422
+ # here. Just convert log(a**b) to b*log(a) and let
423
+ # log_new_extension() handle it from there.
424
+ lbase = log(i.args[0].base)
425
+ logs.append(lbase)
426
+ new = i.args[0].exp*lbase
427
+ self.newf = self.newf.xreplace({i: new})
428
+ self.backsubs.append((new, i))
429
+
430
+ # remove any duplicates
431
+ logs = sorted(set(logs), key=default_sort_key)
432
+
433
+ return logs, symlogs
434
+
435
+ def _auto_attrs(self):
436
+ """
437
+ Set attributes that are generated automatically.
438
+ """
439
+ if not self.T:
440
+ # i.e., when using the extension flag and T isn't given
441
+ self.T = [i.gen for i in self.D]
442
+ if not self.x:
443
+ self.x = self.T[0]
444
+ self.cases = [get_case(d, t) for d, t in zip(self.D, self.T)]
445
+ self.level = -1
446
+ self.t = self.T[self.level]
447
+ self.d = self.D[self.level]
448
+ self.case = self.cases[self.level]
449
+
450
+ def _exp_part(self, exps):
451
+ """
452
+ Try to build an exponential extension.
453
+
454
+ Returns
455
+ =======
456
+
457
+ Returns True if there was a new extension, False if there was no new
458
+ extension but it was able to rewrite the given exponentials in terms
459
+ of the existing extension, and None if the entire extension building
460
+ process should be restarted. If the process fails because there is no
461
+ way around an algebraic extension (e.g., exp(log(x)/2)), it will raise
462
+ NotImplementedError.
463
+ """
464
+ from .prde import is_log_deriv_k_t_radical
465
+ new_extension = False
466
+ restart = False
467
+ expargs = [i.exp for i in exps]
468
+ ip = integer_powers(expargs)
469
+ for arg, others in ip:
470
+ # Minimize potential problems with algebraic substitution
471
+ others.sort(key=lambda i: i[1])
472
+
473
+ arga, argd = frac_in(arg, self.t)
474
+ A = is_log_deriv_k_t_radical(arga, argd, self)
475
+
476
+ if A is not None:
477
+ ans, u, n, const = A
478
+ # if n is 1 or -1, it's algebraic, but we can handle it
479
+ if n == -1:
480
+ # This probably will never happen, because
481
+ # Rational.as_numer_denom() returns the negative term in
482
+ # the numerator. But in case that changes, reduce it to
483
+ # n == 1.
484
+ n = 1
485
+ u **= -1
486
+ const *= -1
487
+ ans = [(i, -j) for i, j in ans]
488
+
489
+ if n == 1:
490
+ # Example: exp(x + x**2) over QQ(x, exp(x), exp(x**2))
491
+ self.newf = self.newf.xreplace({exp(arg): exp(const)*Mul(*[
492
+ u**power for u, power in ans])})
493
+ self.newf = self.newf.xreplace({exp(p*exparg):
494
+ exp(const*p) * Mul(*[u**power for u, power in ans])
495
+ for exparg, p in others})
496
+ # TODO: Add something to backsubs to put exp(const*p)
497
+ # back together.
498
+
499
+ continue
500
+
501
+ else:
502
+ # Bad news: we have an algebraic radical. But maybe we
503
+ # could still avoid it by choosing a different extension.
504
+ # For example, integer_powers() won't handle exp(x/2 + 1)
505
+ # over QQ(x, exp(x)), but if we pull out the exp(1), it
506
+ # will. Or maybe we have exp(x + x**2/2), over
507
+ # QQ(x, exp(x), exp(x**2)), which is exp(x)*sqrt(exp(x**2)),
508
+ # but if we use QQ(x, exp(x), exp(x**2/2)), then they will
509
+ # all work.
510
+ #
511
+ # So here is what we do: If there is a non-zero const, pull
512
+ # it out and retry. Also, if len(ans) > 1, then rewrite
513
+ # exp(arg) as the product of exponentials from ans, and
514
+ # retry that. If const == 0 and len(ans) == 1, then we
515
+ # assume that it would have been handled by either
516
+ # integer_powers() or n == 1 above if it could be handled,
517
+ # so we give up at that point. For example, you can never
518
+ # handle exp(log(x)/2) because it equals sqrt(x).
519
+
520
+ if const or len(ans) > 1:
521
+ rad = Mul(*[term**(power/n) for term, power in ans])
522
+ self.newf = self.newf.xreplace({exp(p*exparg):
523
+ exp(const*p)*rad for exparg, p in others})
524
+ self.newf = self.newf.xreplace(dict(list(zip(reversed(self.T),
525
+ reversed([f(self.x) for f in self.Tfuncs])))))
526
+ restart = True
527
+ break
528
+ else:
529
+ # TODO: give algebraic dependence in error string
530
+ raise NotImplementedError("Cannot integrate over "
531
+ "algebraic extensions.")
532
+
533
+ else:
534
+ arga, argd = frac_in(arg, self.t)
535
+ darga = (argd*derivation(Poly(arga, self.t), self) -
536
+ arga*derivation(Poly(argd, self.t), self))
537
+ dargd = argd**2
538
+ darga, dargd = darga.cancel(dargd, include=True)
539
+ darg = darga.as_expr()/dargd.as_expr()
540
+ self.t = next(self.ts)
541
+ self.T.append(self.t)
542
+ self.extargs.append(arg)
543
+ self.exts.append('exp')
544
+ self.D.append(darg.as_poly(self.t, expand=False)*Poly(self.t,
545
+ self.t, expand=False))
546
+ if self.dummy:
547
+ i = Dummy("i")
548
+ else:
549
+ i = Symbol('i')
550
+ self.Tfuncs += [Lambda(i, exp(arg.subs(self.x, i)))]
551
+ self.newf = self.newf.xreplace(
552
+ {exp(exparg): self.t**p for exparg, p in others})
553
+ new_extension = True
554
+
555
+ if restart:
556
+ return None
557
+ return new_extension
558
+
559
+ def _log_part(self, logs):
560
+ """
561
+ Try to build a logarithmic extension.
562
+
563
+ Returns
564
+ =======
565
+
566
+ Returns True if there was a new extension and False if there was no new
567
+ extension but it was able to rewrite the given logarithms in terms
568
+ of the existing extension. Unlike with exponential extensions, there
569
+ is no way that a logarithm is not transcendental over and cannot be
570
+ rewritten in terms of an already existing extension in a non-algebraic
571
+ way, so this function does not ever return None or raise
572
+ NotImplementedError.
573
+ """
574
+ from .prde import is_deriv_k
575
+ new_extension = False
576
+ logargs = [i.args[0] for i in logs]
577
+ for arg in ordered(logargs):
578
+ # The log case is easier, because whenever a logarithm is algebraic
579
+ # over the base field, it is of the form a1*t1 + ... an*tn + c,
580
+ # which is a polynomial, so we can just replace it with that.
581
+ # In other words, we don't have to worry about radicals.
582
+ arga, argd = frac_in(arg, self.t)
583
+ A = is_deriv_k(arga, argd, self)
584
+ if A is not None:
585
+ ans, u, const = A
586
+ newterm = log(const) + u
587
+ self.newf = self.newf.xreplace({log(arg): newterm})
588
+ continue
589
+
590
+ else:
591
+ arga, argd = frac_in(arg, self.t)
592
+ darga = (argd*derivation(Poly(arga, self.t), self) -
593
+ arga*derivation(Poly(argd, self.t), self))
594
+ dargd = argd**2
595
+ darg = darga.as_expr()/dargd.as_expr()
596
+ self.t = next(self.ts)
597
+ self.T.append(self.t)
598
+ self.extargs.append(arg)
599
+ self.exts.append('log')
600
+ self.D.append(cancel(darg.as_expr()/arg).as_poly(self.t,
601
+ expand=False))
602
+ if self.dummy:
603
+ i = Dummy("i")
604
+ else:
605
+ i = Symbol('i')
606
+ self.Tfuncs += [Lambda(i, log(arg.subs(self.x, i)))]
607
+ self.newf = self.newf.xreplace({log(arg): self.t})
608
+ new_extension = True
609
+
610
+ return new_extension
611
+
612
+ @property
613
+ def _important_attrs(self):
614
+ """
615
+ Returns some of the more important attributes of self.
616
+
617
+ Explanation
618
+ ===========
619
+
620
+ Used for testing and debugging purposes.
621
+
622
+ The attributes are (fa, fd, D, T, Tfuncs, backsubs,
623
+ exts, extargs).
624
+ """
625
+ return (self.fa, self.fd, self.D, self.T, self.Tfuncs,
626
+ self.backsubs, self.exts, self.extargs)
627
+
628
+ # NOTE: this printing doesn't follow the Python's standard
629
+ # eval(repr(DE)) == DE, where DE is the DifferentialExtension object,
630
+ # also this printing is supposed to contain all the important
631
+ # attributes of a DifferentialExtension object
632
+ def __repr__(self):
633
+ # no need to have GeneratorType object printed in it
634
+ r = [(attr, getattr(self, attr)) for attr in self.__slots__
635
+ if not isinstance(getattr(self, attr), GeneratorType)]
636
+ return self.__class__.__name__ + '(dict(%r))' % (r)
637
+
638
+ # fancy printing of DifferentialExtension object
639
+ def __str__(self):
640
+ return (self.__class__.__name__ + '({fa=%s, fd=%s, D=%s})' %
641
+ (self.fa, self.fd, self.D))
642
+
643
+ # should only be used for debugging purposes, internally
644
+ # f1 = f2 = log(x) at different places in code execution
645
+ # may return D1 != D2 as True, since 'level' or other attribute
646
+ # may differ
647
+ def __eq__(self, other):
648
+ for attr in self.__class__.__slots__:
649
+ d1, d2 = getattr(self, attr), getattr(other, attr)
650
+ if not (isinstance(d1, GeneratorType) or d1 == d2):
651
+ return False
652
+ return True
653
+
654
+ def reset(self):
655
+ """
656
+ Reset self to an initial state. Used by __init__.
657
+ """
658
+ self.t = self.x
659
+ self.T = [self.x]
660
+ self.D = [Poly(1, self.x)]
661
+ self.level = -1
662
+ self.exts = [None]
663
+ self.extargs = [None]
664
+ if self.dummy:
665
+ self.ts = numbered_symbols('t', cls=Dummy)
666
+ else:
667
+ # For testing
668
+ self.ts = numbered_symbols('t')
669
+ # For various things that we change to make things work that we need to
670
+ # change back when we are done.
671
+ self.backsubs = []
672
+ self.Tfuncs = []
673
+ self.newf = self.f
674
+
675
+ def indices(self, extension):
676
+ """
677
+ Parameters
678
+ ==========
679
+
680
+ extension : str
681
+ Represents a valid extension type.
682
+
683
+ Returns
684
+ =======
685
+
686
+ list: A list of indices of 'exts' where extension of
687
+ type 'extension' is present.
688
+
689
+ Examples
690
+ ========
691
+
692
+ >>> from sympy.integrals.risch import DifferentialExtension
693
+ >>> from sympy import log, exp
694
+ >>> from sympy.abc import x
695
+ >>> DE = DifferentialExtension(log(x) + exp(x), x, handle_first='exp')
696
+ >>> DE.indices('log')
697
+ [2]
698
+ >>> DE.indices('exp')
699
+ [1]
700
+
701
+ """
702
+ return [i for i, ext in enumerate(self.exts) if ext == extension]
703
+
704
+ def increment_level(self):
705
+ """
706
+ Increment the level of self.
707
+
708
+ Explanation
709
+ ===========
710
+
711
+ This makes the working differential extension larger. self.level is
712
+ given relative to the end of the list (-1, -2, etc.), so we do not need
713
+ do worry about it when building the extension.
714
+ """
715
+ if self.level >= -1:
716
+ raise ValueError("The level of the differential extension cannot "
717
+ "be incremented any further.")
718
+
719
+ self.level += 1
720
+ self.t = self.T[self.level]
721
+ self.d = self.D[self.level]
722
+ self.case = self.cases[self.level]
723
+ return None
724
+
725
+ def decrement_level(self):
726
+ """
727
+ Decrease the level of self.
728
+
729
+ Explanation
730
+ ===========
731
+
732
+ This makes the working differential extension smaller. self.level is
733
+ given relative to the end of the list (-1, -2, etc.), so we do not need
734
+ do worry about it when building the extension.
735
+ """
736
+ if self.level <= -len(self.T):
737
+ raise ValueError("The level of the differential extension cannot "
738
+ "be decremented any further.")
739
+
740
+ self.level -= 1
741
+ self.t = self.T[self.level]
742
+ self.d = self.D[self.level]
743
+ self.case = self.cases[self.level]
744
+ return None
745
+
746
+
747
+ def update_sets(seq, atoms, func):
748
+ s = set(seq)
749
+ s = atoms.intersection(s)
750
+ new = atoms - s
751
+ s.update(list(filter(func, new)))
752
+ return list(s)
753
+
754
+
755
+ class DecrementLevel:
756
+ """
757
+ A context manager for decrementing the level of a DifferentialExtension.
758
+ """
759
+ __slots__ = ('DE',)
760
+
761
+ def __init__(self, DE):
762
+ self.DE = DE
763
+ return
764
+
765
+ def __enter__(self):
766
+ self.DE.decrement_level()
767
+
768
+ def __exit__(self, exc_type, exc_value, traceback):
769
+ self.DE.increment_level()
770
+
771
+
772
+ class NonElementaryIntegralException(Exception):
773
+ """
774
+ Exception used by subroutines within the Risch algorithm to indicate to one
775
+ another that the function being integrated does not have an elementary
776
+ integral in the given differential field.
777
+ """
778
+ # TODO: Rewrite algorithms below to use this (?)
779
+
780
+ # TODO: Pass through information about why the integral was nonelementary,
781
+ # and store that in the resulting NonElementaryIntegral somehow.
782
+ pass
783
+
784
+
785
+ def gcdex_diophantine(a, b, c):
786
+ """
787
+ Extended Euclidean Algorithm, Diophantine version.
788
+
789
+ Explanation
790
+ ===========
791
+
792
+ Given ``a``, ``b`` in K[x] and ``c`` in (a, b), the ideal generated by ``a`` and
793
+ ``b``, return (s, t) such that s*a + t*b == c and either s == 0 or s.degree()
794
+ < b.degree().
795
+ """
796
+ # Extended Euclidean Algorithm (Diophantine Version) pg. 13
797
+ # TODO: This should go in densetools.py.
798
+ # XXX: Bettter name?
799
+
800
+ s, g = a.half_gcdex(b)
801
+ s *= c.exquo(g) # Inexact division means c is not in (a, b)
802
+ if s and s.degree() >= b.degree():
803
+ _, s = s.div(b)
804
+ t = (c - s*a).exquo(b)
805
+ return (s, t)
806
+
807
+
808
+ def frac_in(f, t, *, cancel=False, **kwargs):
809
+ """
810
+ Returns the tuple (fa, fd), where fa and fd are Polys in t.
811
+
812
+ Explanation
813
+ ===========
814
+
815
+ This is a common idiom in the Risch Algorithm functions, so we abstract
816
+ it out here. ``f`` should be a basic expression, a Poly, or a tuple (fa, fd),
817
+ where fa and fd are either basic expressions or Polys, and f == fa/fd.
818
+ **kwargs are applied to Poly.
819
+ """
820
+ if isinstance(f, tuple):
821
+ fa, fd = f
822
+ f = fa.as_expr()/fd.as_expr()
823
+ fa, fd = f.as_expr().as_numer_denom()
824
+ fa, fd = fa.as_poly(t, **kwargs), fd.as_poly(t, **kwargs)
825
+ if cancel:
826
+ fa, fd = fa.cancel(fd, include=True)
827
+ if fa is None or fd is None:
828
+ raise ValueError("Could not turn %s into a fraction in %s." % (f, t))
829
+ return (fa, fd)
830
+
831
+
832
+ def as_poly_1t(p, t, z):
833
+ """
834
+ (Hackish) way to convert an element ``p`` of K[t, 1/t] to K[t, z].
835
+
836
+ In other words, ``z == 1/t`` will be a dummy variable that Poly can handle
837
+ better.
838
+
839
+ See issue 5131.
840
+
841
+ Examples
842
+ ========
843
+
844
+ >>> from sympy import random_poly
845
+ >>> from sympy.integrals.risch import as_poly_1t
846
+ >>> from sympy.abc import x, z
847
+
848
+ >>> p1 = random_poly(x, 10, -10, 10)
849
+ >>> p2 = random_poly(x, 10, -10, 10)
850
+ >>> p = p1 + p2.subs(x, 1/x)
851
+ >>> as_poly_1t(p, x, z).as_expr().subs(z, 1/x) == p
852
+ True
853
+ """
854
+ # TODO: Use this on the final result. That way, we can avoid answers like
855
+ # (...)*exp(-x).
856
+ pa, pd = frac_in(p, t, cancel=True)
857
+ if not pd.is_monomial:
858
+ # XXX: Is there a better Poly exception that we could raise here?
859
+ # Either way, if you see this (from the Risch Algorithm) it indicates
860
+ # a bug.
861
+ raise PolynomialError("%s is not an element of K[%s, 1/%s]." % (p, t, t))
862
+ d = pd.degree(t)
863
+ one_t_part = pa.slice(0, d + 1)
864
+ r = pd.degree() - pa.degree()
865
+ t_part = pa - one_t_part
866
+ try:
867
+ t_part = t_part.to_field().exquo(pd)
868
+ except DomainError as e:
869
+ # issue 4950
870
+ raise NotImplementedError(e)
871
+ # Compute the negative degree parts.
872
+ one_t_part = Poly.from_list(reversed(one_t_part.rep.rep), *one_t_part.gens,
873
+ domain=one_t_part.domain)
874
+ if 0 < r < oo:
875
+ one_t_part *= Poly(t**r, t)
876
+
877
+ one_t_part = one_t_part.replace(t, z) # z will be 1/t
878
+ if pd.nth(d):
879
+ one_t_part *= Poly(1/pd.nth(d), z, expand=False)
880
+ ans = t_part.as_poly(t, z, expand=False) + one_t_part.as_poly(t, z,
881
+ expand=False)
882
+
883
+ return ans
884
+
885
+
886
+ def derivation(p, DE, coefficientD=False, basic=False):
887
+ """
888
+ Computes Dp.
889
+
890
+ Explanation
891
+ ===========
892
+
893
+ Given the derivation D with D = d/dx and p is a polynomial in t over
894
+ K(x), return Dp.
895
+
896
+ If coefficientD is True, it computes the derivation kD
897
+ (kappaD), which is defined as kD(sum(ai*Xi**i, (i, 0, n))) ==
898
+ sum(Dai*Xi**i, (i, 1, n)) (Definition 3.2.2, page 80). X in this case is
899
+ T[-1], so coefficientD computes the derivative just with respect to T[:-1],
900
+ with T[-1] treated as a constant.
901
+
902
+ If ``basic=True``, the returns a Basic expression. Elements of D can still be
903
+ instances of Poly.
904
+ """
905
+ if basic:
906
+ r = 0
907
+ else:
908
+ r = Poly(0, DE.t)
909
+
910
+ t = DE.t
911
+ if coefficientD:
912
+ if DE.level <= -len(DE.T):
913
+ # 'base' case, the answer is 0.
914
+ return r
915
+ DE.decrement_level()
916
+
917
+ D = DE.D[:len(DE.D) + DE.level + 1]
918
+ T = DE.T[:len(DE.T) + DE.level + 1]
919
+
920
+ for d, v in zip(D, T):
921
+ pv = p.as_poly(v)
922
+ if pv is None or basic:
923
+ pv = p.as_expr()
924
+
925
+ if basic:
926
+ r += d.as_expr()*pv.diff(v)
927
+ else:
928
+ r += (d.as_expr()*pv.diff(v).as_expr()).as_poly(t)
929
+
930
+ if basic:
931
+ r = cancel(r)
932
+ if coefficientD:
933
+ DE.increment_level()
934
+
935
+ return r
936
+
937
+
938
+ def get_case(d, t):
939
+ """
940
+ Returns the type of the derivation d.
941
+
942
+ Returns one of {'exp', 'tan', 'base', 'primitive', 'other_linear',
943
+ 'other_nonlinear'}.
944
+ """
945
+ if not d.expr.has(t):
946
+ if d.is_one:
947
+ return 'base'
948
+ return 'primitive'
949
+ if d.rem(Poly(t, t)).is_zero:
950
+ return 'exp'
951
+ if d.rem(Poly(1 + t**2, t)).is_zero:
952
+ return 'tan'
953
+ if d.degree(t) > 1:
954
+ return 'other_nonlinear'
955
+ return 'other_linear'
956
+
957
+
958
+ def splitfactor(p, DE, coefficientD=False, z=None):
959
+ """
960
+ Splitting factorization.
961
+
962
+ Explanation
963
+ ===========
964
+
965
+ Given a derivation D on k[t] and ``p`` in k[t], return (p_n, p_s) in
966
+ k[t] x k[t] such that p = p_n*p_s, p_s is special, and each square
967
+ factor of p_n is normal.
968
+
969
+ Page. 100
970
+ """
971
+ kinv = [1/x for x in DE.T[:DE.level]]
972
+ if z:
973
+ kinv.append(z)
974
+
975
+ One = Poly(1, DE.t, domain=p.get_domain())
976
+ Dp = derivation(p, DE, coefficientD=coefficientD)
977
+ # XXX: Is this right?
978
+ if p.is_zero:
979
+ return (p, One)
980
+
981
+ if not p.expr.has(DE.t):
982
+ s = p.as_poly(*kinv).gcd(Dp.as_poly(*kinv)).as_poly(DE.t)
983
+ n = p.exquo(s)
984
+ return (n, s)
985
+
986
+ if not Dp.is_zero:
987
+ h = p.gcd(Dp).to_field()
988
+ g = p.gcd(p.diff(DE.t)).to_field()
989
+ s = h.exquo(g)
990
+
991
+ if s.degree(DE.t) == 0:
992
+ return (p, One)
993
+
994
+ q_split = splitfactor(p.exquo(s), DE, coefficientD=coefficientD)
995
+
996
+ return (q_split[0], q_split[1]*s)
997
+ else:
998
+ return (p, One)
999
+
1000
+
1001
+ def splitfactor_sqf(p, DE, coefficientD=False, z=None, basic=False):
1002
+ """
1003
+ Splitting Square-free Factorization.
1004
+
1005
+ Explanation
1006
+ ===========
1007
+
1008
+ Given a derivation D on k[t] and ``p`` in k[t], returns (N1, ..., Nm)
1009
+ and (S1, ..., Sm) in k[t]^m such that p =
1010
+ (N1*N2**2*...*Nm**m)*(S1*S2**2*...*Sm**m) is a splitting
1011
+ factorization of ``p`` and the Ni and Si are square-free and coprime.
1012
+ """
1013
+ # TODO: This algorithm appears to be faster in every case
1014
+ # TODO: Verify this and splitfactor() for multiple extensions
1015
+ kkinv = [1/x for x in DE.T[:DE.level]] + DE.T[:DE.level]
1016
+ if z:
1017
+ kkinv = [z]
1018
+
1019
+ S = []
1020
+ N = []
1021
+ p_sqf = p.sqf_list_include()
1022
+ if p.is_zero:
1023
+ return (((p, 1),), ())
1024
+
1025
+ for pi, i in p_sqf:
1026
+ Si = pi.as_poly(*kkinv).gcd(derivation(pi, DE,
1027
+ coefficientD=coefficientD,basic=basic).as_poly(*kkinv)).as_poly(DE.t)
1028
+ pi = Poly(pi, DE.t)
1029
+ Si = Poly(Si, DE.t)
1030
+ Ni = pi.exquo(Si)
1031
+ if not Si.is_one:
1032
+ S.append((Si, i))
1033
+ if not Ni.is_one:
1034
+ N.append((Ni, i))
1035
+
1036
+ return (tuple(N), tuple(S))
1037
+
1038
+
1039
+ def canonical_representation(a, d, DE):
1040
+ """
1041
+ Canonical Representation.
1042
+
1043
+ Explanation
1044
+ ===========
1045
+
1046
+ Given a derivation D on k[t] and f = a/d in k(t), return (f_p, f_s,
1047
+ f_n) in k[t] x k(t) x k(t) such that f = f_p + f_s + f_n is the
1048
+ canonical representation of f (f_p is a polynomial, f_s is reduced
1049
+ (has a special denominator), and f_n is simple (has a normal
1050
+ denominator).
1051
+ """
1052
+ # Make d monic
1053
+ l = Poly(1/d.LC(), DE.t)
1054
+ a, d = a.mul(l), d.mul(l)
1055
+
1056
+ q, r = a.div(d)
1057
+ dn, ds = splitfactor(d, DE)
1058
+
1059
+ b, c = gcdex_diophantine(dn.as_poly(DE.t), ds.as_poly(DE.t), r.as_poly(DE.t))
1060
+ b, c = b.as_poly(DE.t), c.as_poly(DE.t)
1061
+
1062
+ return (q, (b, ds), (c, dn))
1063
+
1064
+
1065
+ def hermite_reduce(a, d, DE):
1066
+ """
1067
+ Hermite Reduction - Mack's Linear Version.
1068
+
1069
+ Given a derivation D on k(t) and f = a/d in k(t), returns g, h, r in
1070
+ k(t) such that f = Dg + h + r, h is simple, and r is reduced.
1071
+
1072
+ """
1073
+ # Make d monic
1074
+ l = Poly(1/d.LC(), DE.t)
1075
+ a, d = a.mul(l), d.mul(l)
1076
+
1077
+ fp, fs, fn = canonical_representation(a, d, DE)
1078
+ a, d = fn
1079
+ l = Poly(1/d.LC(), DE.t)
1080
+ a, d = a.mul(l), d.mul(l)
1081
+
1082
+ ga = Poly(0, DE.t)
1083
+ gd = Poly(1, DE.t)
1084
+
1085
+ dd = derivation(d, DE)
1086
+ dm = gcd(d.to_field(), dd.to_field()).as_poly(DE.t)
1087
+ ds, _ = d.div(dm)
1088
+
1089
+ while dm.degree(DE.t) > 0:
1090
+
1091
+ ddm = derivation(dm, DE)
1092
+ dm2 = gcd(dm.to_field(), ddm.to_field())
1093
+ dms, _ = dm.div(dm2)
1094
+ ds_ddm = ds.mul(ddm)
1095
+ ds_ddm_dm, _ = ds_ddm.div(dm)
1096
+
1097
+ b, c = gcdex_diophantine(-ds_ddm_dm.as_poly(DE.t),
1098
+ dms.as_poly(DE.t), a.as_poly(DE.t))
1099
+ b, c = b.as_poly(DE.t), c.as_poly(DE.t)
1100
+
1101
+ db = derivation(b, DE).as_poly(DE.t)
1102
+ ds_dms, _ = ds.div(dms)
1103
+ a = c.as_poly(DE.t) - db.mul(ds_dms).as_poly(DE.t)
1104
+
1105
+ ga = ga*dm + b*gd
1106
+ gd = gd*dm
1107
+ ga, gd = ga.cancel(gd, include=True)
1108
+ dm = dm2
1109
+
1110
+ q, r = a.div(ds)
1111
+ ga, gd = ga.cancel(gd, include=True)
1112
+
1113
+ r, d = r.cancel(ds, include=True)
1114
+ rra = q*fs[1] + fp*fs[1] + fs[0]
1115
+ rrd = fs[1]
1116
+ rra, rrd = rra.cancel(rrd, include=True)
1117
+
1118
+ return ((ga, gd), (r, d), (rra, rrd))
1119
+
1120
+
1121
+ def polynomial_reduce(p, DE):
1122
+ """
1123
+ Polynomial Reduction.
1124
+
1125
+ Explanation
1126
+ ===========
1127
+
1128
+ Given a derivation D on k(t) and p in k[t] where t is a nonlinear
1129
+ monomial over k, return q, r in k[t] such that p = Dq + r, and
1130
+ deg(r) < deg_t(Dt).
1131
+ """
1132
+ q = Poly(0, DE.t)
1133
+ while p.degree(DE.t) >= DE.d.degree(DE.t):
1134
+ m = p.degree(DE.t) - DE.d.degree(DE.t) + 1
1135
+ q0 = Poly(DE.t**m, DE.t).mul(Poly(p.as_poly(DE.t).LC()/
1136
+ (m*DE.d.LC()), DE.t))
1137
+ q += q0
1138
+ p = p - derivation(q0, DE)
1139
+
1140
+ return (q, p)
1141
+
1142
+
1143
+ def laurent_series(a, d, F, n, DE):
1144
+ """
1145
+ Contribution of ``F`` to the full partial fraction decomposition of A/D.
1146
+
1147
+ Explanation
1148
+ ===========
1149
+
1150
+ Given a field K of characteristic 0 and ``A``,``D``,``F`` in K[x] with D monic,
1151
+ nonzero, coprime with A, and ``F`` the factor of multiplicity n in the square-
1152
+ free factorization of D, return the principal parts of the Laurent series of
1153
+ A/D at all the zeros of ``F``.
1154
+ """
1155
+ if F.degree()==0:
1156
+ return 0
1157
+ Z = _symbols('z', n)
1158
+ z = Symbol('z')
1159
+ Z.insert(0, z)
1160
+ delta_a = Poly(0, DE.t)
1161
+ delta_d = Poly(1, DE.t)
1162
+
1163
+ E = d.quo(F**n)
1164
+ ha, hd = (a, E*Poly(z**n, DE.t))
1165
+ dF = derivation(F,DE)
1166
+ B, _ = gcdex_diophantine(E, F, Poly(1,DE.t))
1167
+ C, _ = gcdex_diophantine(dF, F, Poly(1,DE.t))
1168
+
1169
+ # initialization
1170
+ F_store = F
1171
+ V, DE_D_list, H_list= [], [], []
1172
+
1173
+ for j in range(0, n):
1174
+ # jth derivative of z would be substituted with dfnth/(j+1) where dfnth =(d^n)f/(dx)^n
1175
+ F_store = derivation(F_store, DE)
1176
+ v = (F_store.as_expr())/(j + 1)
1177
+ V.append(v)
1178
+ DE_D_list.append(Poly(Z[j + 1],Z[j]))
1179
+
1180
+ DE_new = DifferentialExtension(extension = {'D': DE_D_list}) #a differential indeterminate
1181
+ for j in range(0, n):
1182
+ zEha = Poly(z**(n + j), DE.t)*E**(j + 1)*ha
1183
+ zEhd = hd
1184
+ Pa, Pd = cancel((zEha, zEhd))[1], cancel((zEha, zEhd))[2]
1185
+ Q = Pa.quo(Pd)
1186
+ for i in range(0, j + 1):
1187
+ Q = Q.subs(Z[i], V[i])
1188
+ Dha = (hd*derivation(ha, DE, basic=True).as_poly(DE.t)
1189
+ + ha*derivation(hd, DE, basic=True).as_poly(DE.t)
1190
+ + hd*derivation(ha, DE_new, basic=True).as_poly(DE.t)
1191
+ + ha*derivation(hd, DE_new, basic=True).as_poly(DE.t))
1192
+ Dhd = Poly(j + 1, DE.t)*hd**2
1193
+ ha, hd = Dha, Dhd
1194
+
1195
+ Ff, _ = F.div(gcd(F, Q))
1196
+ F_stara, F_stard = frac_in(Ff, DE.t)
1197
+ if F_stara.degree(DE.t) - F_stard.degree(DE.t) > 0:
1198
+ QBC = Poly(Q, DE.t)*B**(1 + j)*C**(n + j)
1199
+ H = QBC
1200
+ H_list.append(H)
1201
+ H = (QBC*F_stard).rem(F_stara)
1202
+ alphas = real_roots(F_stara)
1203
+ for alpha in list(alphas):
1204
+ delta_a = delta_a*Poly((DE.t - alpha)**(n - j), DE.t) + Poly(H.eval(alpha), DE.t)
1205
+ delta_d = delta_d*Poly((DE.t - alpha)**(n - j), DE.t)
1206
+ return (delta_a, delta_d, H_list)
1207
+
1208
+
1209
+ def recognize_derivative(a, d, DE, z=None):
1210
+ """
1211
+ Compute the squarefree factorization of the denominator of f
1212
+ and for each Di the polynomial H in K[x] (see Theorem 2.7.1), using the
1213
+ LaurentSeries algorithm. Write Di = GiEi where Gj = gcd(Hn, Di) and
1214
+ gcd(Ei,Hn) = 1. Since the residues of f at the roots of Gj are all 0, and
1215
+ the residue of f at a root alpha of Ei is Hi(a) != 0, f is the derivative of a
1216
+ rational function if and only if Ei = 1 for each i, which is equivalent to
1217
+ Di | H[-1] for each i.
1218
+ """
1219
+ flag =True
1220
+ a, d = a.cancel(d, include=True)
1221
+ _, r = a.div(d)
1222
+ Np, Sp = splitfactor_sqf(d, DE, coefficientD=True, z=z)
1223
+
1224
+ j = 1
1225
+ for s, _ in Sp:
1226
+ delta_a, delta_d, H = laurent_series(r, d, s, j, DE)
1227
+ g = gcd(d, H[-1]).as_poly()
1228
+ if g is not d:
1229
+ flag = False
1230
+ break
1231
+ j = j + 1
1232
+ return flag
1233
+
1234
+
1235
+ def recognize_log_derivative(a, d, DE, z=None):
1236
+ """
1237
+ There exists a v in K(x)* such that f = dv/v
1238
+ where f a rational function if and only if f can be written as f = A/D
1239
+ where D is squarefree,deg(A) < deg(D), gcd(A, D) = 1,
1240
+ and all the roots of the Rothstein-Trager resultant are integers. In that case,
1241
+ any of the Rothstein-Trager, Lazard-Rioboo-Trager or Czichowski algorithm
1242
+ produces u in K(x) such that du/dx = uf.
1243
+ """
1244
+
1245
+ z = z or Dummy('z')
1246
+ a, d = a.cancel(d, include=True)
1247
+ _, a = a.div(d)
1248
+
1249
+ pz = Poly(z, DE.t)
1250
+ Dd = derivation(d, DE)
1251
+ q = a - pz*Dd
1252
+ r, _ = d.resultant(q, includePRS=True)
1253
+ r = Poly(r, z)
1254
+ Np, Sp = splitfactor_sqf(r, DE, coefficientD=True, z=z)
1255
+
1256
+ for s, _ in Sp:
1257
+ # TODO also consider the complex roots which should
1258
+ # turn the flag false
1259
+ a = real_roots(s.as_poly(z))
1260
+
1261
+ if not all(j.is_Integer for j in a):
1262
+ return False
1263
+ return True
1264
+
1265
+ def residue_reduce(a, d, DE, z=None, invert=True):
1266
+ """
1267
+ Lazard-Rioboo-Rothstein-Trager resultant reduction.
1268
+
1269
+ Explanation
1270
+ ===========
1271
+
1272
+ Given a derivation ``D`` on k(t) and f in k(t) simple, return g
1273
+ elementary over k(t) and a Boolean b in {True, False} such that f -
1274
+ Dg in k[t] if b == True or f + h and f + h - Dg do not have an
1275
+ elementary integral over k(t) for any h in k<t> (reduced) if b ==
1276
+ False.
1277
+
1278
+ Returns (G, b), where G is a tuple of tuples of the form (s_i, S_i),
1279
+ such that g = Add(*[RootSum(s_i, lambda z: z*log(S_i(z, t))) for
1280
+ S_i, s_i in G]). f - Dg is the remaining integral, which is elementary
1281
+ only if b == True, and hence the integral of f is elementary only if
1282
+ b == True.
1283
+
1284
+ f - Dg is not calculated in this function because that would require
1285
+ explicitly calculating the RootSum. Use residue_reduce_derivation().
1286
+ """
1287
+ # TODO: Use log_to_atan() from rationaltools.py
1288
+ # If r = residue_reduce(...), then the logarithmic part is given by:
1289
+ # sum([RootSum(a[0].as_poly(z), lambda i: i*log(a[1].as_expr()).subs(z,
1290
+ # i)).subs(t, log(x)) for a in r[0]])
1291
+
1292
+ z = z or Dummy('z')
1293
+ a, d = a.cancel(d, include=True)
1294
+ a, d = a.to_field().mul_ground(1/d.LC()), d.to_field().mul_ground(1/d.LC())
1295
+ kkinv = [1/x for x in DE.T[:DE.level]] + DE.T[:DE.level]
1296
+
1297
+ if a.is_zero:
1298
+ return ([], True)
1299
+ _, a = a.div(d)
1300
+
1301
+ pz = Poly(z, DE.t)
1302
+
1303
+ Dd = derivation(d, DE)
1304
+ q = a - pz*Dd
1305
+
1306
+ if Dd.degree(DE.t) <= d.degree(DE.t):
1307
+ r, R = d.resultant(q, includePRS=True)
1308
+ else:
1309
+ r, R = q.resultant(d, includePRS=True)
1310
+
1311
+ R_map, H = {}, []
1312
+ for i in R:
1313
+ R_map[i.degree()] = i
1314
+
1315
+ r = Poly(r, z)
1316
+ Np, Sp = splitfactor_sqf(r, DE, coefficientD=True, z=z)
1317
+
1318
+ for s, i in Sp:
1319
+ if i == d.degree(DE.t):
1320
+ s = Poly(s, z).monic()
1321
+ H.append((s, d))
1322
+ else:
1323
+ h = R_map.get(i)
1324
+ if h is None:
1325
+ continue
1326
+ h_lc = Poly(h.as_poly(DE.t).LC(), DE.t, field=True)
1327
+
1328
+ h_lc_sqf = h_lc.sqf_list_include(all=True)
1329
+
1330
+ for a, j in h_lc_sqf:
1331
+ h = Poly(h, DE.t, field=True).exquo(Poly(gcd(a, s**j, *kkinv),
1332
+ DE.t))
1333
+
1334
+ s = Poly(s, z).monic()
1335
+
1336
+ if invert:
1337
+ h_lc = Poly(h.as_poly(DE.t).LC(), DE.t, field=True, expand=False)
1338
+ inv, coeffs = h_lc.as_poly(z, field=True).invert(s), [S.One]
1339
+
1340
+ for coeff in h.coeffs()[1:]:
1341
+ L = reduced(inv*coeff.as_poly(inv.gens), [s])[1]
1342
+ coeffs.append(L.as_expr())
1343
+
1344
+ h = Poly(dict(list(zip(h.monoms(), coeffs))), DE.t)
1345
+
1346
+ H.append((s, h))
1347
+
1348
+ b = not any(cancel(i.as_expr()).has(DE.t, z) for i, _ in Np)
1349
+
1350
+ return (H, b)
1351
+
1352
+
1353
+ def residue_reduce_to_basic(H, DE, z):
1354
+ """
1355
+ Converts the tuple returned by residue_reduce() into a Basic expression.
1356
+ """
1357
+ # TODO: check what Lambda does with RootOf
1358
+ i = Dummy('i')
1359
+ s = list(zip(reversed(DE.T), reversed([f(DE.x) for f in DE.Tfuncs])))
1360
+
1361
+ return sum(RootSum(a[0].as_poly(z), Lambda(i, i*log(a[1].as_expr()).subs(
1362
+ {z: i}).subs(s))) for a in H)
1363
+
1364
+
1365
+ def residue_reduce_derivation(H, DE, z):
1366
+ """
1367
+ Computes the derivation of an expression returned by residue_reduce().
1368
+
1369
+ In general, this is a rational function in t, so this returns an
1370
+ as_expr() result.
1371
+ """
1372
+ # TODO: verify that this is correct for multiple extensions
1373
+ i = Dummy('i')
1374
+ return S(sum(RootSum(a[0].as_poly(z), Lambda(i, i*derivation(a[1],
1375
+ DE).as_expr().subs(z, i)/a[1].as_expr().subs(z, i))) for a in H))
1376
+
1377
+
1378
+ def integrate_primitive_polynomial(p, DE):
1379
+ """
1380
+ Integration of primitive polynomials.
1381
+
1382
+ Explanation
1383
+ ===========
1384
+
1385
+ Given a primitive monomial t over k, and ``p`` in k[t], return q in k[t],
1386
+ r in k, and a bool b in {True, False} such that r = p - Dq is in k if b is
1387
+ True, or r = p - Dq does not have an elementary integral over k(t) if b is
1388
+ False.
1389
+ """
1390
+ Zero = Poly(0, DE.t)
1391
+ q = Poly(0, DE.t)
1392
+
1393
+ if not p.expr.has(DE.t):
1394
+ return (Zero, p, True)
1395
+
1396
+ from .prde import limited_integrate
1397
+ while True:
1398
+ if not p.expr.has(DE.t):
1399
+ return (q, p, True)
1400
+
1401
+ Dta, Dtb = frac_in(DE.d, DE.T[DE.level - 1])
1402
+
1403
+ with DecrementLevel(DE): # We had better be integrating the lowest extension (x)
1404
+ # with ratint().
1405
+ a = p.LC()
1406
+ aa, ad = frac_in(a, DE.t)
1407
+
1408
+ try:
1409
+ rv = limited_integrate(aa, ad, [(Dta, Dtb)], DE)
1410
+ if rv is None:
1411
+ raise NonElementaryIntegralException
1412
+ (ba, bd), c = rv
1413
+ except NonElementaryIntegralException:
1414
+ return (q, p, False)
1415
+
1416
+ m = p.degree(DE.t)
1417
+ q0 = c[0].as_poly(DE.t)*Poly(DE.t**(m + 1)/(m + 1), DE.t) + \
1418
+ (ba.as_expr()/bd.as_expr()).as_poly(DE.t)*Poly(DE.t**m, DE.t)
1419
+
1420
+ p = p - derivation(q0, DE)
1421
+ q = q + q0
1422
+
1423
+
1424
+ def integrate_primitive(a, d, DE, z=None):
1425
+ """
1426
+ Integration of primitive functions.
1427
+
1428
+ Explanation
1429
+ ===========
1430
+
1431
+ Given a primitive monomial t over k and f in k(t), return g elementary over
1432
+ k(t), i in k(t), and b in {True, False} such that i = f - Dg is in k if b
1433
+ is True or i = f - Dg does not have an elementary integral over k(t) if b
1434
+ is False.
1435
+
1436
+ This function returns a Basic expression for the first argument. If b is
1437
+ True, the second argument is Basic expression in k to recursively integrate.
1438
+ If b is False, the second argument is an unevaluated Integral, which has
1439
+ been proven to be nonelementary.
1440
+ """
1441
+ # XXX: a and d must be canceled, or this might return incorrect results
1442
+ z = z or Dummy("z")
1443
+ s = list(zip(reversed(DE.T), reversed([f(DE.x) for f in DE.Tfuncs])))
1444
+
1445
+ g1, h, r = hermite_reduce(a, d, DE)
1446
+ g2, b = residue_reduce(h[0], h[1], DE, z=z)
1447
+ if not b:
1448
+ i = cancel(a.as_expr()/d.as_expr() - (g1[1]*derivation(g1[0], DE) -
1449
+ g1[0]*derivation(g1[1], DE)).as_expr()/(g1[1]**2).as_expr() -
1450
+ residue_reduce_derivation(g2, DE, z))
1451
+ i = NonElementaryIntegral(cancel(i).subs(s), DE.x)
1452
+ return ((g1[0].as_expr()/g1[1].as_expr()).subs(s) +
1453
+ residue_reduce_to_basic(g2, DE, z), i, b)
1454
+
1455
+ # h - Dg2 + r
1456
+ p = cancel(h[0].as_expr()/h[1].as_expr() - residue_reduce_derivation(g2,
1457
+ DE, z) + r[0].as_expr()/r[1].as_expr())
1458
+ p = p.as_poly(DE.t)
1459
+
1460
+ q, i, b = integrate_primitive_polynomial(p, DE)
1461
+
1462
+ ret = ((g1[0].as_expr()/g1[1].as_expr() + q.as_expr()).subs(s) +
1463
+ residue_reduce_to_basic(g2, DE, z))
1464
+ if not b:
1465
+ # TODO: This does not do the right thing when b is False
1466
+ i = NonElementaryIntegral(cancel(i.as_expr()).subs(s), DE.x)
1467
+ else:
1468
+ i = cancel(i.as_expr())
1469
+
1470
+ return (ret, i, b)
1471
+
1472
+
1473
+ def integrate_hyperexponential_polynomial(p, DE, z):
1474
+ """
1475
+ Integration of hyperexponential polynomials.
1476
+
1477
+ Explanation
1478
+ ===========
1479
+
1480
+ Given a hyperexponential monomial t over k and ``p`` in k[t, 1/t], return q in
1481
+ k[t, 1/t] and a bool b in {True, False} such that p - Dq in k if b is True,
1482
+ or p - Dq does not have an elementary integral over k(t) if b is False.
1483
+ """
1484
+ t1 = DE.t
1485
+ dtt = DE.d.exquo(Poly(DE.t, DE.t))
1486
+ qa = Poly(0, DE.t)
1487
+ qd = Poly(1, DE.t)
1488
+ b = True
1489
+
1490
+ if p.is_zero:
1491
+ return(qa, qd, b)
1492
+
1493
+ from sympy.integrals.rde import rischDE
1494
+
1495
+ with DecrementLevel(DE):
1496
+ for i in range(-p.degree(z), p.degree(t1) + 1):
1497
+ if not i:
1498
+ continue
1499
+ elif i < 0:
1500
+ # If you get AttributeError: 'NoneType' object has no attribute 'nth'
1501
+ # then this should really not have expand=False
1502
+ # But it shouldn't happen because p is already a Poly in t and z
1503
+ a = p.as_poly(z, expand=False).nth(-i)
1504
+ else:
1505
+ # If you get AttributeError: 'NoneType' object has no attribute 'nth'
1506
+ # then this should really not have expand=False
1507
+ a = p.as_poly(t1, expand=False).nth(i)
1508
+
1509
+ aa, ad = frac_in(a, DE.t, field=True)
1510
+ aa, ad = aa.cancel(ad, include=True)
1511
+ iDt = Poly(i, t1)*dtt
1512
+ iDta, iDtd = frac_in(iDt, DE.t, field=True)
1513
+ try:
1514
+ va, vd = rischDE(iDta, iDtd, Poly(aa, DE.t), Poly(ad, DE.t), DE)
1515
+ va, vd = frac_in((va, vd), t1, cancel=True)
1516
+ except NonElementaryIntegralException:
1517
+ b = False
1518
+ else:
1519
+ qa = qa*vd + va*Poly(t1**i)*qd
1520
+ qd *= vd
1521
+
1522
+ return (qa, qd, b)
1523
+
1524
+
1525
+ def integrate_hyperexponential(a, d, DE, z=None, conds='piecewise'):
1526
+ """
1527
+ Integration of hyperexponential functions.
1528
+
1529
+ Explanation
1530
+ ===========
1531
+
1532
+ Given a hyperexponential monomial t over k and f in k(t), return g
1533
+ elementary over k(t), i in k(t), and a bool b in {True, False} such that
1534
+ i = f - Dg is in k if b is True or i = f - Dg does not have an elementary
1535
+ integral over k(t) if b is False.
1536
+
1537
+ This function returns a Basic expression for the first argument. If b is
1538
+ True, the second argument is Basic expression in k to recursively integrate.
1539
+ If b is False, the second argument is an unevaluated Integral, which has
1540
+ been proven to be nonelementary.
1541
+ """
1542
+ # XXX: a and d must be canceled, or this might return incorrect results
1543
+ z = z or Dummy("z")
1544
+ s = list(zip(reversed(DE.T), reversed([f(DE.x) for f in DE.Tfuncs])))
1545
+
1546
+ g1, h, r = hermite_reduce(a, d, DE)
1547
+ g2, b = residue_reduce(h[0], h[1], DE, z=z)
1548
+ if not b:
1549
+ i = cancel(a.as_expr()/d.as_expr() - (g1[1]*derivation(g1[0], DE) -
1550
+ g1[0]*derivation(g1[1], DE)).as_expr()/(g1[1]**2).as_expr() -
1551
+ residue_reduce_derivation(g2, DE, z))
1552
+ i = NonElementaryIntegral(cancel(i.subs(s)), DE.x)
1553
+ return ((g1[0].as_expr()/g1[1].as_expr()).subs(s) +
1554
+ residue_reduce_to_basic(g2, DE, z), i, b)
1555
+
1556
+ # p should be a polynomial in t and 1/t, because Sirr == k[t, 1/t]
1557
+ # h - Dg2 + r
1558
+ p = cancel(h[0].as_expr()/h[1].as_expr() - residue_reduce_derivation(g2,
1559
+ DE, z) + r[0].as_expr()/r[1].as_expr())
1560
+ pp = as_poly_1t(p, DE.t, z)
1561
+
1562
+ qa, qd, b = integrate_hyperexponential_polynomial(pp, DE, z)
1563
+
1564
+ i = pp.nth(0, 0)
1565
+
1566
+ ret = ((g1[0].as_expr()/g1[1].as_expr()).subs(s) \
1567
+ + residue_reduce_to_basic(g2, DE, z))
1568
+
1569
+ qas = qa.as_expr().subs(s)
1570
+ qds = qd.as_expr().subs(s)
1571
+ if conds == 'piecewise' and DE.x not in qds.free_symbols:
1572
+ # We have to be careful if the exponent is S.Zero!
1573
+
1574
+ # XXX: Does qd = 0 always necessarily correspond to the exponential
1575
+ # equaling 1?
1576
+ ret += Piecewise(
1577
+ (qas/qds, Ne(qds, 0)),
1578
+ (integrate((p - i).subs(DE.t, 1).subs(s), DE.x), True)
1579
+ )
1580
+ else:
1581
+ ret += qas/qds
1582
+
1583
+ if not b:
1584
+ i = p - (qd*derivation(qa, DE) - qa*derivation(qd, DE)).as_expr()/\
1585
+ (qd**2).as_expr()
1586
+ i = NonElementaryIntegral(cancel(i).subs(s), DE.x)
1587
+ return (ret, i, b)
1588
+
1589
+
1590
+ def integrate_hypertangent_polynomial(p, DE):
1591
+ """
1592
+ Integration of hypertangent polynomials.
1593
+
1594
+ Explanation
1595
+ ===========
1596
+
1597
+ Given a differential field k such that sqrt(-1) is not in k, a
1598
+ hypertangent monomial t over k, and p in k[t], return q in k[t] and
1599
+ c in k such that p - Dq - c*D(t**2 + 1)/(t**1 + 1) is in k and p -
1600
+ Dq does not have an elementary integral over k(t) if Dc != 0.
1601
+ """
1602
+ # XXX: Make sure that sqrt(-1) is not in k.
1603
+ q, r = polynomial_reduce(p, DE)
1604
+ a = DE.d.exquo(Poly(DE.t**2 + 1, DE.t))
1605
+ c = Poly(r.nth(1)/(2*a.as_expr()), DE.t)
1606
+ return (q, c)
1607
+
1608
+
1609
+ def integrate_nonlinear_no_specials(a, d, DE, z=None):
1610
+ """
1611
+ Integration of nonlinear monomials with no specials.
1612
+
1613
+ Explanation
1614
+ ===========
1615
+
1616
+ Given a nonlinear monomial t over k such that Sirr ({p in k[t] | p is
1617
+ special, monic, and irreducible}) is empty, and f in k(t), returns g
1618
+ elementary over k(t) and a Boolean b in {True, False} such that f - Dg is
1619
+ in k if b == True, or f - Dg does not have an elementary integral over k(t)
1620
+ if b == False.
1621
+
1622
+ This function is applicable to all nonlinear extensions, but in the case
1623
+ where it returns b == False, it will only have proven that the integral of
1624
+ f - Dg is nonelementary if Sirr is empty.
1625
+
1626
+ This function returns a Basic expression.
1627
+ """
1628
+ # TODO: Integral from k?
1629
+ # TODO: split out nonelementary integral
1630
+ # XXX: a and d must be canceled, or this might not return correct results
1631
+ z = z or Dummy("z")
1632
+ s = list(zip(reversed(DE.T), reversed([f(DE.x) for f in DE.Tfuncs])))
1633
+
1634
+ g1, h, r = hermite_reduce(a, d, DE)
1635
+ g2, b = residue_reduce(h[0], h[1], DE, z=z)
1636
+ if not b:
1637
+ return ((g1[0].as_expr()/g1[1].as_expr()).subs(s) +
1638
+ residue_reduce_to_basic(g2, DE, z), b)
1639
+
1640
+ # Because f has no specials, this should be a polynomial in t, or else
1641
+ # there is a bug.
1642
+ p = cancel(h[0].as_expr()/h[1].as_expr() - residue_reduce_derivation(g2,
1643
+ DE, z).as_expr() + r[0].as_expr()/r[1].as_expr()).as_poly(DE.t)
1644
+ q1, q2 = polynomial_reduce(p, DE)
1645
+
1646
+ if q2.expr.has(DE.t):
1647
+ b = False
1648
+ else:
1649
+ b = True
1650
+
1651
+ ret = (cancel(g1[0].as_expr()/g1[1].as_expr() + q1.as_expr()).subs(s) +
1652
+ residue_reduce_to_basic(g2, DE, z))
1653
+ return (ret, b)
1654
+
1655
+
1656
+ class NonElementaryIntegral(Integral):
1657
+ """
1658
+ Represents a nonelementary Integral.
1659
+
1660
+ Explanation
1661
+ ===========
1662
+
1663
+ If the result of integrate() is an instance of this class, it is
1664
+ guaranteed to be nonelementary. Note that integrate() by default will try
1665
+ to find any closed-form solution, even in terms of special functions which
1666
+ may themselves not be elementary. To make integrate() only give
1667
+ elementary solutions, or, in the cases where it can prove the integral to
1668
+ be nonelementary, instances of this class, use integrate(risch=True).
1669
+ In this case, integrate() may raise NotImplementedError if it cannot make
1670
+ such a determination.
1671
+
1672
+ integrate() uses the deterministic Risch algorithm to integrate elementary
1673
+ functions or prove that they have no elementary integral. In some cases,
1674
+ this algorithm can split an integral into an elementary and nonelementary
1675
+ part, so that the result of integrate will be the sum of an elementary
1676
+ expression and a NonElementaryIntegral.
1677
+
1678
+ Examples
1679
+ ========
1680
+
1681
+ >>> from sympy import integrate, exp, log, Integral
1682
+ >>> from sympy.abc import x
1683
+
1684
+ >>> a = integrate(exp(-x**2), x, risch=True)
1685
+ >>> print(a)
1686
+ Integral(exp(-x**2), x)
1687
+ >>> type(a)
1688
+ <class 'sympy.integrals.risch.NonElementaryIntegral'>
1689
+
1690
+ >>> expr = (2*log(x)**2 - log(x) - x**2)/(log(x)**3 - x**2*log(x))
1691
+ >>> b = integrate(expr, x, risch=True)
1692
+ >>> print(b)
1693
+ -log(-x + log(x))/2 + log(x + log(x))/2 + Integral(1/log(x), x)
1694
+ >>> type(b.atoms(Integral).pop())
1695
+ <class 'sympy.integrals.risch.NonElementaryIntegral'>
1696
+
1697
+ """
1698
+ # TODO: This is useful in and of itself, because isinstance(result,
1699
+ # NonElementaryIntegral) will tell if the integral has been proven to be
1700
+ # elementary. But should we do more? Perhaps a no-op .doit() if
1701
+ # elementary=True? Or maybe some information on why the integral is
1702
+ # nonelementary.
1703
+ pass
1704
+
1705
+
1706
+ def risch_integrate(f, x, extension=None, handle_first='log',
1707
+ separate_integral=False, rewrite_complex=None,
1708
+ conds='piecewise'):
1709
+ r"""
1710
+ The Risch Integration Algorithm.
1711
+
1712
+ Explanation
1713
+ ===========
1714
+
1715
+ Only transcendental functions are supported. Currently, only exponentials
1716
+ and logarithms are supported, but support for trigonometric functions is
1717
+ forthcoming.
1718
+
1719
+ If this function returns an unevaluated Integral in the result, it means
1720
+ that it has proven that integral to be nonelementary. Any errors will
1721
+ result in raising NotImplementedError. The unevaluated Integral will be
1722
+ an instance of NonElementaryIntegral, a subclass of Integral.
1723
+
1724
+ handle_first may be either 'exp' or 'log'. This changes the order in
1725
+ which the extension is built, and may result in a different (but
1726
+ equivalent) solution (for an example of this, see issue 5109). It is also
1727
+ possible that the integral may be computed with one but not the other,
1728
+ because not all cases have been implemented yet. It defaults to 'log' so
1729
+ that the outer extension is exponential when possible, because more of the
1730
+ exponential case has been implemented.
1731
+
1732
+ If ``separate_integral`` is ``True``, the result is returned as a tuple (ans, i),
1733
+ where the integral is ans + i, ans is elementary, and i is either a
1734
+ NonElementaryIntegral or 0. This useful if you want to try further
1735
+ integrating the NonElementaryIntegral part using other algorithms to
1736
+ possibly get a solution in terms of special functions. It is False by
1737
+ default.
1738
+
1739
+ Examples
1740
+ ========
1741
+
1742
+ >>> from sympy.integrals.risch import risch_integrate
1743
+ >>> from sympy import exp, log, pprint
1744
+ >>> from sympy.abc import x
1745
+
1746
+ First, we try integrating exp(-x**2). Except for a constant factor of
1747
+ 2/sqrt(pi), this is the famous error function.
1748
+
1749
+ >>> pprint(risch_integrate(exp(-x**2), x))
1750
+ /
1751
+ |
1752
+ | 2
1753
+ | -x
1754
+ | e dx
1755
+ |
1756
+ /
1757
+
1758
+ The unevaluated Integral in the result means that risch_integrate() has
1759
+ proven that exp(-x**2) does not have an elementary anti-derivative.
1760
+
1761
+ In many cases, risch_integrate() can split out the elementary
1762
+ anti-derivative part from the nonelementary anti-derivative part.
1763
+ For example,
1764
+
1765
+ >>> pprint(risch_integrate((2*log(x)**2 - log(x) - x**2)/(log(x)**3 -
1766
+ ... x**2*log(x)), x))
1767
+ /
1768
+ |
1769
+ log(-x + log(x)) log(x + log(x)) | 1
1770
+ - ---------------- + --------------- + | ------ dx
1771
+ 2 2 | log(x)
1772
+ |
1773
+ /
1774
+
1775
+ This means that it has proven that the integral of 1/log(x) is
1776
+ nonelementary. This function is also known as the logarithmic integral,
1777
+ and is often denoted as Li(x).
1778
+
1779
+ risch_integrate() currently only accepts purely transcendental functions
1780
+ with exponentials and logarithms, though note that this can include
1781
+ nested exponentials and logarithms, as well as exponentials with bases
1782
+ other than E.
1783
+
1784
+ >>> pprint(risch_integrate(exp(x)*exp(exp(x)), x))
1785
+ / x\
1786
+ \e /
1787
+ e
1788
+ >>> pprint(risch_integrate(exp(exp(x)), x))
1789
+ /
1790
+ |
1791
+ | / x\
1792
+ | \e /
1793
+ | e dx
1794
+ |
1795
+ /
1796
+
1797
+ >>> pprint(risch_integrate(x*x**x*log(x) + x**x + x*x**x, x))
1798
+ x
1799
+ x*x
1800
+ >>> pprint(risch_integrate(x**x, x))
1801
+ /
1802
+ |
1803
+ | x
1804
+ | x dx
1805
+ |
1806
+ /
1807
+
1808
+ >>> pprint(risch_integrate(-1/(x*log(x)*log(log(x))**2), x))
1809
+ 1
1810
+ -----------
1811
+ log(log(x))
1812
+
1813
+ """
1814
+ f = S(f)
1815
+
1816
+ DE = extension or DifferentialExtension(f, x, handle_first=handle_first,
1817
+ dummy=True, rewrite_complex=rewrite_complex)
1818
+ fa, fd = DE.fa, DE.fd
1819
+
1820
+ result = S.Zero
1821
+ for case in reversed(DE.cases):
1822
+ if not fa.expr.has(DE.t) and not fd.expr.has(DE.t) and not case == 'base':
1823
+ DE.decrement_level()
1824
+ fa, fd = frac_in((fa, fd), DE.t)
1825
+ continue
1826
+
1827
+ fa, fd = fa.cancel(fd, include=True)
1828
+ if case == 'exp':
1829
+ ans, i, b = integrate_hyperexponential(fa, fd, DE, conds=conds)
1830
+ elif case == 'primitive':
1831
+ ans, i, b = integrate_primitive(fa, fd, DE)
1832
+ elif case == 'base':
1833
+ # XXX: We can't call ratint() directly here because it doesn't
1834
+ # handle polynomials correctly.
1835
+ ans = integrate(fa.as_expr()/fd.as_expr(), DE.x, risch=False)
1836
+ b = False
1837
+ i = S.Zero
1838
+ else:
1839
+ raise NotImplementedError("Only exponential and logarithmic "
1840
+ "extensions are currently supported.")
1841
+
1842
+ result += ans
1843
+ if b:
1844
+ DE.decrement_level()
1845
+ fa, fd = frac_in(i, DE.t)
1846
+ else:
1847
+ result = result.subs(DE.backsubs)
1848
+ if not i.is_zero:
1849
+ i = NonElementaryIntegral(i.function.subs(DE.backsubs),i.limits)
1850
+ if not separate_integral:
1851
+ result += i
1852
+ return result
1853
+ else:
1854
+
1855
+ if isinstance(i, NonElementaryIntegral):
1856
+ return (result, i)
1857
+ else:
1858
+ return (result, 0)
venv/lib/python3.10/site-packages/sympy/integrals/singularityfunctions.py ADDED
@@ -0,0 +1,63 @@
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
+ from sympy.functions import SingularityFunction, DiracDelta
2
+ from sympy.integrals import integrate
3
+
4
+
5
+ def singularityintegrate(f, x):
6
+ """
7
+ This function handles the indefinite integrations of Singularity functions.
8
+ The ``integrate`` function calls this function internally whenever an
9
+ instance of SingularityFunction is passed as argument.
10
+
11
+ Explanation
12
+ ===========
13
+
14
+ The idea for integration is the following:
15
+
16
+ - If we are dealing with a SingularityFunction expression,
17
+ i.e. ``SingularityFunction(x, a, n)``, we just return
18
+ ``SingularityFunction(x, a, n + 1)/(n + 1)`` if ``n >= 0`` and
19
+ ``SingularityFunction(x, a, n + 1)`` if ``n < 0``.
20
+
21
+ - If the node is a multiplication or power node having a
22
+ SingularityFunction term we rewrite the whole expression in terms of
23
+ Heaviside and DiracDelta and then integrate the output. Lastly, we
24
+ rewrite the output of integration back in terms of SingularityFunction.
25
+
26
+ - If none of the above case arises, we return None.
27
+
28
+ Examples
29
+ ========
30
+
31
+ >>> from sympy.integrals.singularityfunctions import singularityintegrate
32
+ >>> from sympy import SingularityFunction, symbols, Function
33
+ >>> x, a, n, y = symbols('x a n y')
34
+ >>> f = Function('f')
35
+ >>> singularityintegrate(SingularityFunction(x, a, 3), x)
36
+ SingularityFunction(x, a, 4)/4
37
+ >>> singularityintegrate(5*SingularityFunction(x, 5, -2), x)
38
+ 5*SingularityFunction(x, 5, -1)
39
+ >>> singularityintegrate(6*SingularityFunction(x, 5, -1), x)
40
+ 6*SingularityFunction(x, 5, 0)
41
+ >>> singularityintegrate(x*SingularityFunction(x, 0, -1), x)
42
+ 0
43
+ >>> singularityintegrate(SingularityFunction(x, 1, -1) * f(x), x)
44
+ f(1)*SingularityFunction(x, 1, 0)
45
+
46
+ """
47
+
48
+ if not f.has(SingularityFunction):
49
+ return None
50
+
51
+ if isinstance(f, SingularityFunction):
52
+ x, a, n = f.args
53
+ if n.is_positive or n.is_zero:
54
+ return SingularityFunction(x, a, n + 1)/(n + 1)
55
+ elif n in (-1, -2):
56
+ return SingularityFunction(x, a, n + 1)
57
+
58
+ if f.is_Mul or f.is_Pow:
59
+
60
+ expr = f.rewrite(DiracDelta)
61
+ expr = integrate(expr, x)
62
+ return expr.rewrite(SingularityFunction)
63
+ return None
venv/lib/python3.10/site-packages/sympy/integrals/tests/__init__.py ADDED
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