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@@ -185,3 +185,4 @@ env-llmeval/lib/python3.10/site-packages/pyarrow/libarrow_acero.so.1500 filter=l
 env-llmeval/lib/python3.10/site-packages/pyarrow/libarrow_substrait.so.1500 filter=lfs diff=lfs merge=lfs -text
 env-llmeval/lib/python3.10/site-packages/pyarrow/lib.cpython-310-x86_64-linux-gnu.so filter=lfs diff=lfs merge=lfs -text
 env-llmeval/lib/python3.10/site-packages/pyarrow/libarrow_flight.so.1500 filter=lfs diff=lfs merge=lfs -text
+llmeval-env/lib/python3.10/site-packages/scipy/stats/_unuran/unuran_wrapper.cpython-310-x86_64-linux-gnu.so filter=lfs diff=lfs merge=lfs -text

llmeval-env/lib/python3.10/site-packages/scipy/constants/tests/test_codata.py

@@ -0,0 +1,57 @@
+from scipy.constants import find, value, ConstantWarning, c, speed_of_light
+from numpy.testing import (assert_equal, assert_, assert_almost_equal,
+                           suppress_warnings)
+import scipy.constants._codata as _cd
+
+
+def test_find():
+    keys = find('weak mixing', disp=False)
+    assert_equal(keys, ['weak mixing angle'])
+
+    keys = find('qwertyuiop', disp=False)
+    assert_equal(keys, [])
+
+    keys = find('natural unit', disp=False)
+    assert_equal(keys, sorted(['natural unit of velocity',
+                                'natural unit of action',
+                                'natural unit of action in eV s',
+                                'natural unit of mass',
+                                'natural unit of energy',
+                                'natural unit of energy in MeV',
+                                'natural unit of momentum',
+                                'natural unit of momentum in MeV/c',
+                                'natural unit of length',
+                                'natural unit of time']))
+
+
+def test_basic_table_parse():
+    c_s = 'speed of light in vacuum'
+    assert_equal(value(c_s), c)
+    assert_equal(value(c_s), speed_of_light)
+
+
+def test_basic_lookup():
+    assert_equal('%d %s' % (_cd.c, _cd.unit('speed of light in vacuum')),
+                 '299792458 m s^-1')
+
+
+def test_find_all():
+    assert_(len(find(disp=False)) > 300)
+
+
+def test_find_single():
+    assert_equal(find('Wien freq', disp=False)[0],
+                 'Wien frequency displacement law constant')
+
+
+def test_2002_vs_2006():
+    assert_almost_equal(value('magn. flux quantum'),
+                        value('mag. flux quantum'))
+
+
+def test_exact_values():
+    # Check that updating stored values with exact ones worked.
+    with suppress_warnings() as sup:
+        sup.filter(ConstantWarning)
+        for key in _cd.exact_values:
+            assert_((_cd.exact_values[key][0] - value(key)) / value(key) == 0)

llmeval-env/lib/python3.10/site-packages/scipy/constants/tests/test_constants.py

@@ -0,0 +1,35 @@
+from numpy.testing import assert_equal, assert_allclose
+import scipy.constants as sc
+
+
+def test_convert_temperature():
+    assert_equal(sc.convert_temperature(32, 'f', 'Celsius'), 0)
+    assert_equal(sc.convert_temperature([0, 0], 'celsius', 'Kelvin'),
+                 [273.15, 273.15])
+    assert_equal(sc.convert_temperature([0, 0], 'kelvin', 'c'),
+                 [-273.15, -273.15])
+    assert_equal(sc.convert_temperature([32, 32], 'f', 'k'), [273.15, 273.15])
+    assert_equal(sc.convert_temperature([273.15, 273.15], 'kelvin', 'F'),
+                 [32, 32])
+    assert_equal(sc.convert_temperature([0, 0], 'C', 'fahrenheit'), [32, 32])
+    assert_allclose(sc.convert_temperature([0, 0], 'c', 'r'), [491.67, 491.67],
+                    rtol=0., atol=1e-13)
+    assert_allclose(sc.convert_temperature([491.67, 491.67], 'Rankine', 'C'),
+                    [0., 0.], rtol=0., atol=1e-13)
+    assert_allclose(sc.convert_temperature([491.67, 491.67], 'r', 'F'),
+                    [32., 32.], rtol=0., atol=1e-13)
+    assert_allclose(sc.convert_temperature([32, 32], 'fahrenheit', 'R'),
+                    [491.67, 491.67], rtol=0., atol=1e-13)
+    assert_allclose(sc.convert_temperature([273.15, 273.15], 'K', 'R'),
+                    [491.67, 491.67], rtol=0., atol=1e-13)
+    assert_allclose(sc.convert_temperature([491.67, 0.], 'rankine', 'kelvin'),
+                    [273.15, 0.], rtol=0., atol=1e-13)
+
+
+def test_lambda_to_nu():
+    assert_equal(sc.lambda2nu([sc.speed_of_light, 1]), [1, sc.speed_of_light])
+
+
+def test_nu_to_lambda():
+    assert_equal(sc.nu2lambda([sc.speed_of_light, 1]), [1, sc.speed_of_light])
+

llmeval-env/lib/python3.10/site-packages/scipy/integrate/__init__.py

@@ -0,0 +1,110 @@
+"""
+=============================================
+Integration and ODEs (:mod:`scipy.integrate`)
+=============================================
+
+.. currentmodule:: scipy.integrate
+
+Integrating functions, given function object
+============================================
+
+.. autosummary::
+   :toctree: generated/
+
+   quad          -- General purpose integration
+   quad_vec      -- General purpose integration of vector-valued functions
+   dblquad       -- General purpose double integration
+   tplquad       -- General purpose triple integration
+   nquad         -- General purpose N-D integration
+   fixed_quad    -- Integrate func(x) using Gaussian quadrature of order n
+   quadrature    -- Integrate with given tolerance using Gaussian quadrature
+   romberg       -- Integrate func using Romberg integration
+   newton_cotes  -- Weights and error coefficient for Newton-Cotes integration
+   qmc_quad      -- N-D integration using Quasi-Monte Carlo quadrature
+   IntegrationWarning -- Warning on issues during integration
+   AccuracyWarning  -- Warning on issues during quadrature integration
+
+Integrating functions, given fixed samples
+==========================================
+
+.. autosummary::
+   :toctree: generated/
+
+   trapezoid            -- Use trapezoidal rule to compute integral.
+   cumulative_trapezoid -- Use trapezoidal rule to cumulatively compute integral.
+   simpson              -- Use Simpson's rule to compute integral from samples.
+   cumulative_simpson   -- Use Simpson's rule to cumulatively compute integral from samples.
+   romb                 -- Use Romberg Integration to compute integral from
+                        -- (2**k + 1) evenly-spaced samples.
+
+.. seealso::
+
+   :mod:`scipy.special` for orthogonal polynomials (special) for Gaussian
+   quadrature roots and weights for other weighting factors and regions.
+
+Solving initial value problems for ODE systems
+==============================================
+
+The solvers are implemented as individual classes, which can be used directly
+(low-level usage) or through a convenience function.
+
+.. autosummary::
+   :toctree: generated/
+
+   solve_ivp     -- Convenient function for ODE integration.
+   RK23          -- Explicit Runge-Kutta solver of order 3(2).
+   RK45          -- Explicit Runge-Kutta solver of order 5(4).
+   DOP853        -- Explicit Runge-Kutta solver of order 8.
+   Radau         -- Implicit Runge-Kutta solver of order 5.
+   BDF           -- Implicit multi-step variable order (1 to 5) solver.
+   LSODA         -- LSODA solver from ODEPACK Fortran package.
+   OdeSolver     -- Base class for ODE solvers.
+   DenseOutput   -- Local interpolant for computing a dense output.
+   OdeSolution   -- Class which represents a continuous ODE solution.
+
+
+Old API
+-------
+
+These are the routines developed earlier for SciPy. They wrap older solvers
+implemented in Fortran (mostly ODEPACK). While the interface to them is not
+particularly convenient and certain features are missing compared to the new
+API, the solvers themselves are of good quality and work fast as compiled
+Fortran code. In some cases, it might be worth using this old API.
+
+.. autosummary::
+   :toctree: generated/
+
+   odeint        -- General integration of ordinary differential equations.
+   ode           -- Integrate ODE using VODE and ZVODE routines.
+   complex_ode   -- Convert a complex-valued ODE to real-valued and integrate.
+   ODEintWarning -- Warning raised during the execution of `odeint`.
+
+
+Solving boundary value problems for ODE systems
+===============================================
+
+.. autosummary::
+   :toctree: generated/
+
+   solve_bvp     -- Solve a boundary value problem for a system of ODEs.
+"""  # noqa: E501
+
+
+from ._quadrature import *
+from ._odepack_py import *
+from ._quadpack_py import *
+from ._ode import *
+from ._bvp import solve_bvp
+from ._ivp import (solve_ivp, OdeSolution, DenseOutput,
+                   OdeSolver, RK23, RK45, DOP853, Radau, BDF, LSODA)
+from ._quad_vec import quad_vec
+
+# Deprecated namespaces, to be removed in v2.0.0
+from . import dop, lsoda, vode, odepack, quadpack
+
+__all__ = [s for s in dir() if not s.startswith('_')]
+
+from scipy._lib._testutils import PytestTester
+test = PytestTester(__name__)
+del PytestTester

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/__init__.py

@@ -0,0 +1,8 @@
+"""Suite of ODE solvers implemented in Python."""
+from .ivp import solve_ivp
+from .rk import RK23, RK45, DOP853
+from .radau import Radau
+from .bdf import BDF
+from .lsoda import LSODA
+from .common import OdeSolution
+from .base import DenseOutput, OdeSolver

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/base.py

@@ -0,0 +1,290 @@
+import numpy as np
+
+
+def check_arguments(fun, y0, support_complex):
+    """Helper function for checking arguments common to all solvers."""
+    y0 = np.asarray(y0)
+    if np.issubdtype(y0.dtype, np.complexfloating):
+        if not support_complex:
+            raise ValueError("`y0` is complex, but the chosen solver does "
+                             "not support integration in a complex domain.")
+        dtype = complex
+    else:
+        dtype = float
+    y0 = y0.astype(dtype, copy=False)
+
+    if y0.ndim != 1:
+        raise ValueError("`y0` must be 1-dimensional.")
+
+    if not np.isfinite(y0).all():
+        raise ValueError("All components of the initial state `y0` must be finite.")
+
+    def fun_wrapped(t, y):
+        return np.asarray(fun(t, y), dtype=dtype)
+
+    return fun_wrapped, y0
+
+
+class OdeSolver:
+    """Base class for ODE solvers.
+
+    In order to implement a new solver you need to follow the guidelines:
+
+        1. A constructor must accept parameters presented in the base class
+           (listed below) along with any other parameters specific to a solver.
+        2. A constructor must accept arbitrary extraneous arguments
+           ``**extraneous``, but warn that these arguments are irrelevant
+           using `common.warn_extraneous` function. Do not pass these
+           arguments to the base class.
+        3. A solver must implement a private method `_step_impl(self)` which
+           propagates a solver one step further. It must return tuple
+           ``(success, message)``, where ``success`` is a boolean indicating
+           whether a step was successful, and ``message`` is a string
+           containing description of a failure if a step failed or None
+           otherwise.
+        4. A solver must implement a private method `_dense_output_impl(self)`,
+           which returns a `DenseOutput` object covering the last successful
+           step.
+        5. A solver must have attributes listed below in Attributes section.
+           Note that ``t_old`` and ``step_size`` are updated automatically.
+        6. Use `fun(self, t, y)` method for the system rhs evaluation, this
+           way the number of function evaluations (`nfev`) will be tracked
+           automatically.
+        7. For convenience, a base class provides `fun_single(self, t, y)` and
+           `fun_vectorized(self, t, y)` for evaluating the rhs in
+           non-vectorized and vectorized fashions respectively (regardless of
+           how `fun` from the constructor is implemented). These calls don't
+           increment `nfev`.
+        8. If a solver uses a Jacobian matrix and LU decompositions, it should
+           track the number of Jacobian evaluations (`njev`) and the number of
+           LU decompositions (`nlu`).
+        9. By convention, the function evaluations used to compute a finite
+           difference approximation of the Jacobian should not be counted in
+           `nfev`, thus use `fun_single(self, t, y)` or
+           `fun_vectorized(self, t, y)` when computing a finite difference
+           approximation of the Jacobian.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system: the time derivative of the state ``y``
+        at time ``t``. The calling signature is ``fun(t, y)``, where ``t`` is a
+        scalar and ``y`` is an ndarray with ``len(y) = len(y0)``. ``fun`` must
+        return an array of the same shape as ``y``. See `vectorized` for more
+        information.
+    t0 : float
+        Initial time.
+    y0 : array_like, shape (n,)
+        Initial state.
+    t_bound : float
+        Boundary time --- the integration won't continue beyond it. It also
+        determines the direction of the integration.
+    vectorized : bool
+        Whether `fun` can be called in a vectorized fashion. Default is False.
+
+        If ``vectorized`` is False, `fun` will always be called with ``y`` of
+        shape ``(n,)``, where ``n = len(y0)``.
+
+        If ``vectorized`` is True, `fun` may be called with ``y`` of shape
+        ``(n, k)``, where ``k`` is an integer. In this case, `fun` must behave
+        such that ``fun(t, y)[:, i] == fun(t, y[:, i])`` (i.e. each column of
+        the returned array is the time derivative of the state corresponding
+        with a column of ``y``).
+
+        Setting ``vectorized=True`` allows for faster finite difference
+        approximation of the Jacobian by methods 'Radau' and 'BDF', but
+        will result in slower execution for other methods. It can also
+        result in slower overall execution for 'Radau' and 'BDF' in some
+        circumstances (e.g. small ``len(y0)``).
+    support_complex : bool, optional
+        Whether integration in a complex domain should be supported.
+        Generally determined by a derived solver class capabilities.
+        Default is False.
+
+    Attributes
+    ----------
+    n : int
+        Number of equations.
+    status : string
+        Current status of the solver: 'running', 'finished' or 'failed'.
+    t_bound : float
+        Boundary time.
+    direction : float
+        Integration direction: +1 or -1.
+    t : float
+        Current time.
+    y : ndarray
+        Current state.
+    t_old : float
+        Previous time. None if no steps were made yet.
+    step_size : float
+        Size of the last successful step. None if no steps were made yet.
+    nfev : int
+        Number of the system's rhs evaluations.
+    njev : int
+        Number of the Jacobian evaluations.
+    nlu : int
+        Number of LU decompositions.
+    """
+    TOO_SMALL_STEP = "Required step size is less than spacing between numbers."
+
+    def __init__(self, fun, t0, y0, t_bound, vectorized,
+                 support_complex=False):
+        self.t_old = None
+        self.t = t0
+        self._fun, self.y = check_arguments(fun, y0, support_complex)
+        self.t_bound = t_bound
+        self.vectorized = vectorized
+
+        if vectorized:
+            def fun_single(t, y):
+                return self._fun(t, y[:, None]).ravel()
+            fun_vectorized = self._fun
+        else:
+            fun_single = self._fun
+
+            def fun_vectorized(t, y):
+                f = np.empty_like(y)
+                for i, yi in enumerate(y.T):
+                    f[:, i] = self._fun(t, yi)
+                return f
+
+        def fun(t, y):
+            self.nfev += 1
+            return self.fun_single(t, y)
+
+        self.fun = fun
+        self.fun_single = fun_single
+        self.fun_vectorized = fun_vectorized
+
+        self.direction = np.sign(t_bound - t0) if t_bound != t0 else 1
+        self.n = self.y.size
+        self.status = 'running'
+
+        self.nfev = 0
+        self.njev = 0
+        self.nlu = 0
+
+    @property
+    def step_size(self):
+        if self.t_old is None:
+            return None
+        else:
+            return np.abs(self.t - self.t_old)
+
+    def step(self):
+        """Perform one integration step.
+
+        Returns
+        -------
+        message : string or None
+            Report from the solver. Typically a reason for a failure if
+            `self.status` is 'failed' after the step was taken or None
+            otherwise.
+        """
+        if self.status != 'running':
+            raise RuntimeError("Attempt to step on a failed or finished "
+                               "solver.")
+
+        if self.n == 0 or self.t == self.t_bound:
+            # Handle corner cases of empty solver or no integration.
+            self.t_old = self.t
+            self.t = self.t_bound
+            message = None
+            self.status = 'finished'
+        else:
+            t = self.t
+            success, message = self._step_impl()
+
+            if not success:
+                self.status = 'failed'
+            else:
+                self.t_old = t
+                if self.direction * (self.t - self.t_bound) >= 0:
+                    self.status = 'finished'
+
+        return message
+
+    def dense_output(self):
+        """Compute a local interpolant over the last successful step.
+
+        Returns
+        -------
+        sol : `DenseOutput`
+            Local interpolant over the last successful step.
+        """
+        if self.t_old is None:
+            raise RuntimeError("Dense output is available after a successful "
+                               "step was made.")
+
+        if self.n == 0 or self.t == self.t_old:
+            # Handle corner cases of empty solver and no integration.
+            return ConstantDenseOutput(self.t_old, self.t, self.y)
+        else:
+            return self._dense_output_impl()
+
+    def _step_impl(self):
+        raise NotImplementedError
+
+    def _dense_output_impl(self):
+        raise NotImplementedError
+
+
+class DenseOutput:
+    """Base class for local interpolant over step made by an ODE solver.
+
+    It interpolates between `t_min` and `t_max` (see Attributes below).
+    Evaluation outside this interval is not forbidden, but the accuracy is not
+    guaranteed.
+
+    Attributes
+    ----------
+    t_min, t_max : float
+        Time range of the interpolation.
+    """
+    def __init__(self, t_old, t):
+        self.t_old = t_old
+        self.t = t
+        self.t_min = min(t, t_old)
+        self.t_max = max(t, t_old)
+
+    def __call__(self, t):
+        """Evaluate the interpolant.
+
+        Parameters
+        ----------
+        t : float or array_like with shape (n_points,)
+            Points to evaluate the solution at.
+
+        Returns
+        -------
+        y : ndarray, shape (n,) or (n, n_points)
+            Computed values. Shape depends on whether `t` was a scalar or a
+            1-D array.
+        """
+        t = np.asarray(t)
+        if t.ndim > 1:
+            raise ValueError("`t` must be a float or a 1-D array.")
+        return self._call_impl(t)
+
+    def _call_impl(self, t):
+        raise NotImplementedError
+
+
+class ConstantDenseOutput(DenseOutput):
+    """Constant value interpolator.
+
+    This class used for degenerate integration cases: equal integration limits
+    or a system with 0 equations.
+    """
+    def __init__(self, t_old, t, value):
+        super().__init__(t_old, t)
+        self.value = value
+
+    def _call_impl(self, t):
+        if t.ndim == 0:
+            return self.value
+        else:
+            ret = np.empty((self.value.shape[0], t.shape[0]))
+            ret[:] = self.value[:, None]
+            return ret

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/bdf.py

@@ -0,0 +1,479 @@
+import numpy as np
+from scipy.linalg import lu_factor, lu_solve
+from scipy.sparse import issparse, csc_matrix, eye
+from scipy.sparse.linalg import splu
+from scipy.optimize._numdiff import group_columns
+from .common import (validate_max_step, validate_tol, select_initial_step,
+                     norm, EPS, num_jac, validate_first_step,
+                     warn_extraneous)
+from .base import OdeSolver, DenseOutput
+
+
+MAX_ORDER = 5
+NEWTON_MAXITER = 4
+MIN_FACTOR = 0.2
+MAX_FACTOR = 10
+
+
+def compute_R(order, factor):
+    """Compute the matrix for changing the differences array."""
+    I = np.arange(1, order + 1)[:, None]
+    J = np.arange(1, order + 1)
+    M = np.zeros((order + 1, order + 1))
+    M[1:, 1:] = (I - 1 - factor * J) / I
+    M[0] = 1
+    return np.cumprod(M, axis=0)
+
+
+def change_D(D, order, factor):
+    """Change differences array in-place when step size is changed."""
+    R = compute_R(order, factor)
+    U = compute_R(order, 1)
+    RU = R.dot(U)
+    D[:order + 1] = np.dot(RU.T, D[:order + 1])
+
+
+def solve_bdf_system(fun, t_new, y_predict, c, psi, LU, solve_lu, scale, tol):
+    """Solve the algebraic system resulting from BDF method."""
+    d = 0
+    y = y_predict.copy()
+    dy_norm_old = None
+    converged = False
+    for k in range(NEWTON_MAXITER):
+        f = fun(t_new, y)
+        if not np.all(np.isfinite(f)):
+            break
+
+        dy = solve_lu(LU, c * f - psi - d)
+        dy_norm = norm(dy / scale)
+
+        if dy_norm_old is None:
+            rate = None
+        else:
+            rate = dy_norm / dy_norm_old
+
+        if (rate is not None and (rate >= 1 or
+                rate ** (NEWTON_MAXITER - k) / (1 - rate) * dy_norm > tol)):
+            break
+
+        y += dy
+        d += dy
+
+        if (dy_norm == 0 or
+                rate is not None and rate / (1 - rate) * dy_norm < tol):
+            converged = True
+            break
+
+        dy_norm_old = dy_norm
+
+    return converged, k + 1, y, d
+
+
+class BDF(OdeSolver):
+    """Implicit method based on backward-differentiation formulas.
+
+    This is a variable order method with the order varying automatically from
+    1 to 5. The general framework of the BDF algorithm is described in [1]_.
+    This class implements a quasi-constant step size as explained in [2]_.
+    The error estimation strategy for the constant-step BDF is derived in [3]_.
+    An accuracy enhancement using modified formulas (NDF) [2]_ is also implemented.
+
+    Can be applied in the complex domain.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system: the time derivative of the state ``y``
+        at time ``t``. The calling signature is ``fun(t, y)``, where ``t`` is a
+        scalar and ``y`` is an ndarray with ``len(y) = len(y0)``. ``fun`` must
+        return an array of the same shape as ``y``. See `vectorized` for more
+        information.
+    t0 : float
+        Initial time.
+    y0 : array_like, shape (n,)
+        Initial state.
+    t_bound : float
+        Boundary time - the integration won't continue beyond it. It also
+        determines the direction of the integration.
+    first_step : float or None, optional
+        Initial step size. Default is ``None`` which means that the algorithm
+        should choose.
+    max_step : float, optional
+        Maximum allowed step size. Default is np.inf, i.e., the step size is not
+        bounded and determined solely by the solver.
+    rtol, atol : float and array_like, optional
+        Relative and absolute tolerances. The solver keeps the local error
+        estimates less than ``atol + rtol * abs(y)``. Here `rtol` controls a
+        relative accuracy (number of correct digits), while `atol` controls
+        absolute accuracy (number of correct decimal places). To achieve the
+        desired `rtol`, set `atol` to be smaller than the smallest value that
+        can be expected from ``rtol * abs(y)`` so that `rtol` dominates the
+        allowable error. If `atol` is larger than ``rtol * abs(y)`` the
+        number of correct digits is not guaranteed. Conversely, to achieve the
+        desired `atol` set `rtol` such that ``rtol * abs(y)`` is always smaller
+        than `atol`. If components of y have different scales, it might be
+        beneficial to set different `atol` values for different components by
+        passing array_like with shape (n,) for `atol`. Default values are
+        1e-3 for `rtol` and 1e-6 for `atol`.
+    jac : {None, array_like, sparse_matrix, callable}, optional
+        Jacobian matrix of the right-hand side of the system with respect to y,
+        required by this method. The Jacobian matrix has shape (n, n) and its
+        element (i, j) is equal to ``d f_i / d y_j``.
+        There are three ways to define the Jacobian:
+
+            * If array_like or sparse_matrix, the Jacobian is assumed to
+              be constant.
+            * If callable, the Jacobian is assumed to depend on both
+              t and y; it will be called as ``jac(t, y)`` as necessary.
+              For the 'Radau' and 'BDF' methods, the return value might be a
+              sparse matrix.
+            * If None (default), the Jacobian will be approximated by
+              finite differences.
+
+        It is generally recommended to provide the Jacobian rather than
+        relying on a finite-difference approximation.
+    jac_sparsity : {None, array_like, sparse matrix}, optional
+        Defines a sparsity structure of the Jacobian matrix for a
+        finite-difference approximation. Its shape must be (n, n). This argument
+        is ignored if `jac` is not `None`. If the Jacobian has only few non-zero
+        elements in *each* row, providing the sparsity structure will greatly
+        speed up the computations [4]_. A zero entry means that a corresponding
+        element in the Jacobian is always zero. If None (default), the Jacobian
+        is assumed to be dense.
+    vectorized : bool, optional
+        Whether `fun` can be called in a vectorized fashion. Default is False.
+
+        If ``vectorized`` is False, `fun` will always be called with ``y`` of
+        shape ``(n,)``, where ``n = len(y0)``.
+
+        If ``vectorized`` is True, `fun` may be called with ``y`` of shape
+        ``(n, k)``, where ``k`` is an integer. In this case, `fun` must behave
+        such that ``fun(t, y)[:, i] == fun(t, y[:, i])`` (i.e. each column of
+        the returned array is the time derivative of the state corresponding
+        with a column of ``y``).
+
+        Setting ``vectorized=True`` allows for faster finite difference
+        approximation of the Jacobian by this method, but may result in slower
+        execution overall in some circumstances (e.g. small ``len(y0)``).
+
+    Attributes
+    ----------
+    n : int
+        Number of equations.
+    status : string
+        Current status of the solver: 'running', 'finished' or 'failed'.
+    t_bound : float
+        Boundary time.
+    direction : float
+        Integration direction: +1 or -1.
+    t : float
+        Current time.
+    y : ndarray
+        Current state.
+    t_old : float
+        Previous time. None if no steps were made yet.
+    step_size : float
+        Size of the last successful step. None if no steps were made yet.
+    nfev : int
+        Number of evaluations of the right-hand side.
+    njev : int
+        Number of evaluations of the Jacobian.
+    nlu : int
+        Number of LU decompositions.
+
+    References
+    ----------
+    .. [1] G. D. Byrne, A. C. Hindmarsh, "A Polyalgorithm for the Numerical
+           Solution of Ordinary Differential Equations", ACM Transactions on
+           Mathematical Software, Vol. 1, No. 1, pp. 71-96, March 1975.
+    .. [2] L. F. Shampine, M. W. Reichelt, "THE MATLAB ODE SUITE", SIAM J. SCI.
+           COMPUTE., Vol. 18, No. 1, pp. 1-22, January 1997.
+    .. [3] E. Hairer, G. Wanner, "Solving Ordinary Differential Equations I:
+           Nonstiff Problems", Sec. III.2.
+    .. [4] A. Curtis, M. J. D. Powell, and J. Reid, "On the estimation of
+           sparse Jacobian matrices", Journal of the Institute of Mathematics
+           and its Applications, 13, pp. 117-120, 1974.
+    """
+    def __init__(self, fun, t0, y0, t_bound, max_step=np.inf,
+                 rtol=1e-3, atol=1e-6, jac=None, jac_sparsity=None,
+                 vectorized=False, first_step=None, **extraneous):
+        warn_extraneous(extraneous)
+        super().__init__(fun, t0, y0, t_bound, vectorized,
+                         support_complex=True)
+        self.max_step = validate_max_step(max_step)
+        self.rtol, self.atol = validate_tol(rtol, atol, self.n)
+        f = self.fun(self.t, self.y)
+        if first_step is None:
+            self.h_abs = select_initial_step(self.fun, self.t, self.y, f,
+                                             self.direction, 1,
+                                             self.rtol, self.atol)
+        else:
+            self.h_abs = validate_first_step(first_step, t0, t_bound)
+        self.h_abs_old = None
+        self.error_norm_old = None
+
+        self.newton_tol = max(10 * EPS / rtol, min(0.03, rtol ** 0.5))
+
+        self.jac_factor = None
+        self.jac, self.J = self._validate_jac(jac, jac_sparsity)
+        if issparse(self.J):
+            def lu(A):
+                self.nlu += 1
+                return splu(A)
+
+            def solve_lu(LU, b):
+                return LU.solve(b)
+
+            I = eye(self.n, format='csc', dtype=self.y.dtype)
+        else:
+            def lu(A):
+                self.nlu += 1
+                return lu_factor(A, overwrite_a=True)
+
+            def solve_lu(LU, b):
+                return lu_solve(LU, b, overwrite_b=True)
+
+            I = np.identity(self.n, dtype=self.y.dtype)
+
+        self.lu = lu
+        self.solve_lu = solve_lu
+        self.I = I
+
+        kappa = np.array([0, -0.1850, -1/9, -0.0823, -0.0415, 0])
+        self.gamma = np.hstack((0, np.cumsum(1 / np.arange(1, MAX_ORDER + 1))))
+        self.alpha = (1 - kappa) * self.gamma
+        self.error_const = kappa * self.gamma + 1 / np.arange(1, MAX_ORDER + 2)
+
+        D = np.empty((MAX_ORDER + 3, self.n), dtype=self.y.dtype)
+        D[0] = self.y
+        D[1] = f * self.h_abs * self.direction
+        self.D = D
+
+        self.order = 1
+        self.n_equal_steps = 0
+        self.LU = None
+
+    def _validate_jac(self, jac, sparsity):
+        t0 = self.t
+        y0 = self.y
+
+        if jac is None:
+            if sparsity is not None:
+                if issparse(sparsity):
+                    sparsity = csc_matrix(sparsity)
+                groups = group_columns(sparsity)
+                sparsity = (sparsity, groups)
+
+            def jac_wrapped(t, y):
+                self.njev += 1
+                f = self.fun_single(t, y)
+                J, self.jac_factor = num_jac(self.fun_vectorized, t, y, f,
+                                             self.atol, self.jac_factor,
+                                             sparsity)
+                return J
+            J = jac_wrapped(t0, y0)
+        elif callable(jac):
+            J = jac(t0, y0)
+            self.njev += 1
+            if issparse(J):
+                J = csc_matrix(J, dtype=y0.dtype)
+
+                def jac_wrapped(t, y):
+                    self.njev += 1
+                    return csc_matrix(jac(t, y), dtype=y0.dtype)
+            else:
+                J = np.asarray(J, dtype=y0.dtype)
+
+                def jac_wrapped(t, y):
+                    self.njev += 1
+                    return np.asarray(jac(t, y), dtype=y0.dtype)
+
+            if J.shape != (self.n, self.n):
+                raise ValueError("`jac` is expected to have shape {}, but "
+                                 "actually has {}."
+                                 .format((self.n, self.n), J.shape))
+        else:
+            if issparse(jac):
+                J = csc_matrix(jac, dtype=y0.dtype)
+            else:
+                J = np.asarray(jac, dtype=y0.dtype)
+
+            if J.shape != (self.n, self.n):
+                raise ValueError("`jac` is expected to have shape {}, but "
+                                 "actually has {}."
+                                 .format((self.n, self.n), J.shape))
+            jac_wrapped = None
+
+        return jac_wrapped, J
+
+    def _step_impl(self):
+        t = self.t
+        D = self.D
+
+        max_step = self.max_step
+        min_step = 10 * np.abs(np.nextafter(t, self.direction * np.inf) - t)
+        if self.h_abs > max_step:
+            h_abs = max_step
+            change_D(D, self.order, max_step / self.h_abs)
+            self.n_equal_steps = 0
+        elif self.h_abs < min_step:
+            h_abs = min_step
+            change_D(D, self.order, min_step / self.h_abs)
+            self.n_equal_steps = 0
+        else:
+            h_abs = self.h_abs
+
+        atol = self.atol
+        rtol = self.rtol
+        order = self.order
+
+        alpha = self.alpha
+        gamma = self.gamma
+        error_const = self.error_const
+
+        J = self.J
+        LU = self.LU
+        current_jac = self.jac is None
+
+        step_accepted = False
+        while not step_accepted:
+            if h_abs < min_step:
+                return False, self.TOO_SMALL_STEP
+
+            h = h_abs * self.direction
+            t_new = t + h
+
+            if self.direction * (t_new - self.t_bound) > 0:
+                t_new = self.t_bound
+                change_D(D, order, np.abs(t_new - t) / h_abs)
+                self.n_equal_steps = 0
+                LU = None
+
+            h = t_new - t
+            h_abs = np.abs(h)
+
+            y_predict = np.sum(D[:order + 1], axis=0)
+
+            scale = atol + rtol * np.abs(y_predict)
+            psi = np.dot(D[1: order + 1].T, gamma[1: order + 1]) / alpha[order]
+
+            converged = False
+            c = h / alpha[order]
+            while not converged:
+                if LU is None:
+                    LU = self.lu(self.I - c * J)
+
+                converged, n_iter, y_new, d = solve_bdf_system(
+                    self.fun, t_new, y_predict, c, psi, LU, self.solve_lu,
+                    scale, self.newton_tol)
+
+                if not converged:
+                    if current_jac:
+                        break
+                    J = self.jac(t_new, y_predict)
+                    LU = None
+                    current_jac = True
+
+            if not converged:
+                factor = 0.5
+                h_abs *= factor
+                change_D(D, order, factor)
+                self.n_equal_steps = 0
+                LU = None
+                continue
+
+            safety = 0.9 * (2 * NEWTON_MAXITER + 1) / (2 * NEWTON_MAXITER
+                                                       + n_iter)
+
+            scale = atol + rtol * np.abs(y_new)
+            error = error_const[order] * d
+            error_norm = norm(error / scale)
+
+            if error_norm > 1:
+                factor = max(MIN_FACTOR,
+                             safety * error_norm ** (-1 / (order + 1)))
+                h_abs *= factor
+                change_D(D, order, factor)
+                self.n_equal_steps = 0
+                # As we didn't have problems with convergence, we don't
+                # reset LU here.
+            else:
+                step_accepted = True
+
+        self.n_equal_steps += 1
+
+        self.t = t_new
+        self.y = y_new
+
+        self.h_abs = h_abs
+        self.J = J
+        self.LU = LU
+
+        # Update differences. The principal relation here is
+        # D^{j + 1} y_n = D^{j} y_n - D^{j} y_{n - 1}. Keep in mind that D
+        # contained difference for previous interpolating polynomial and
+        # d = D^{k + 1} y_n. Thus this elegant code follows.
+        D[order + 2] = d - D[order + 1]
+        D[order + 1] = d
+        for i in reversed(range(order + 1)):
+            D[i] += D[i + 1]
+
+        if self.n_equal_steps < order + 1:
+            return True, None
+
+        if order > 1:
+            error_m = error_const[order - 1] * D[order]
+            error_m_norm = norm(error_m / scale)
+        else:
+            error_m_norm = np.inf
+
+        if order < MAX_ORDER:
+            error_p = error_const[order + 1] * D[order + 2]
+            error_p_norm = norm(error_p / scale)
+        else:
+            error_p_norm = np.inf
+
+        error_norms = np.array([error_m_norm, error_norm, error_p_norm])
+        with np.errstate(divide='ignore'):
+            factors = error_norms ** (-1 / np.arange(order, order + 3))
+
+        delta_order = np.argmax(factors) - 1
+        order += delta_order
+        self.order = order
+
+        factor = min(MAX_FACTOR, safety * np.max(factors))
+        self.h_abs *= factor
+        change_D(D, order, factor)
+        self.n_equal_steps = 0
+        self.LU = None
+
+        return True, None
+
+    def _dense_output_impl(self):
+        return BdfDenseOutput(self.t_old, self.t, self.h_abs * self.direction,
+                              self.order, self.D[:self.order + 1].copy())
+
+
+class BdfDenseOutput(DenseOutput):
+    def __init__(self, t_old, t, h, order, D):
+        super().__init__(t_old, t)
+        self.order = order
+        self.t_shift = self.t - h * np.arange(self.order)
+        self.denom = h * (1 + np.arange(self.order))
+        self.D = D
+
+    def _call_impl(self, t):
+        if t.ndim == 0:
+            x = (t - self.t_shift) / self.denom
+            p = np.cumprod(x)
+        else:
+            x = (t - self.t_shift[:, None]) / self.denom[:, None]
+            p = np.cumprod(x, axis=0)
+
+        y = np.dot(self.D[1:].T, p)
+        if y.ndim == 1:
+            y += self.D[0]
+        else:
+            y += self.D[0, :, None]
+
+        return y

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/common.py

@@ -0,0 +1,440 @@
+from itertools import groupby
+from warnings import warn
+import numpy as np
+from scipy.sparse import find, coo_matrix
+
+
+EPS = np.finfo(float).eps
+
+
+def validate_first_step(first_step, t0, t_bound):
+    """Assert that first_step is valid and return it."""
+    if first_step <= 0:
+        raise ValueError("`first_step` must be positive.")
+    if first_step > np.abs(t_bound - t0):
+        raise ValueError("`first_step` exceeds bounds.")
+    return first_step
+
+
+def validate_max_step(max_step):
+    """Assert that max_Step is valid and return it."""
+    if max_step <= 0:
+        raise ValueError("`max_step` must be positive.")
+    return max_step
+
+
+def warn_extraneous(extraneous):
+    """Display a warning for extraneous keyword arguments.
+
+    The initializer of each solver class is expected to collect keyword
+    arguments that it doesn't understand and warn about them. This function
+    prints a warning for each key in the supplied dictionary.
+
+    Parameters
+    ----------
+    extraneous : dict
+        Extraneous keyword arguments
+    """
+    if extraneous:
+        warn("The following arguments have no effect for a chosen solver: {}."
+             .format(", ".join(f"`{x}`" for x in extraneous)),
+             stacklevel=3)
+
+
+def validate_tol(rtol, atol, n):
+    """Validate tolerance values."""
+
+    if np.any(rtol < 100 * EPS):
+        warn("At least one element of `rtol` is too small. "
+             f"Setting `rtol = np.maximum(rtol, {100 * EPS})`.",
+             stacklevel=3)
+        rtol = np.maximum(rtol, 100 * EPS)
+
+    atol = np.asarray(atol)
+    if atol.ndim > 0 and atol.shape != (n,):
+        raise ValueError("`atol` has wrong shape.")
+
+    if np.any(atol < 0):
+        raise ValueError("`atol` must be positive.")
+
+    return rtol, atol
+
+
+def norm(x):
+    """Compute RMS norm."""
+    return np.linalg.norm(x) / x.size ** 0.5
+
+
+def select_initial_step(fun, t0, y0, f0, direction, order, rtol, atol):
+    """Empirically select a good initial step.
+
+    The algorithm is described in [1]_.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system.
+    t0 : float
+        Initial value of the independent variable.
+    y0 : ndarray, shape (n,)
+        Initial value of the dependent variable.
+    f0 : ndarray, shape (n,)
+        Initial value of the derivative, i.e., ``fun(t0, y0)``.
+    direction : float
+        Integration direction.
+    order : float
+        Error estimator order. It means that the error controlled by the
+        algorithm is proportional to ``step_size ** (order + 1)`.
+    rtol : float
+        Desired relative tolerance.
+    atol : float
+        Desired absolute tolerance.
+
+    Returns
+    -------
+    h_abs : float
+        Absolute value of the suggested initial step.
+
+    References
+    ----------
+    .. [1] E. Hairer, S. P. Norsett G. Wanner, "Solving Ordinary Differential
+           Equations I: Nonstiff Problems", Sec. II.4.
+    """
+    if y0.size == 0:
+        return np.inf
+
+    scale = atol + np.abs(y0) * rtol
+    d0 = norm(y0 / scale)
+    d1 = norm(f0 / scale)
+    if d0 < 1e-5 or d1 < 1e-5:
+        h0 = 1e-6
+    else:
+        h0 = 0.01 * d0 / d1
+
+    y1 = y0 + h0 * direction * f0
+    f1 = fun(t0 + h0 * direction, y1)
+    d2 = norm((f1 - f0) / scale) / h0
+
+    if d1 <= 1e-15 and d2 <= 1e-15:
+        h1 = max(1e-6, h0 * 1e-3)
+    else:
+        h1 = (0.01 / max(d1, d2)) ** (1 / (order + 1))
+
+    return min(100 * h0, h1)
+
+
+class OdeSolution:
+    """Continuous ODE solution.
+
+    It is organized as a collection of `DenseOutput` objects which represent
+    local interpolants. It provides an algorithm to select a right interpolant
+    for each given point.
+
+    The interpolants cover the range between `t_min` and `t_max` (see
+    Attributes below). Evaluation outside this interval is not forbidden, but
+    the accuracy is not guaranteed.
+
+    When evaluating at a breakpoint (one of the values in `ts`) a segment with
+    the lower index is selected.
+
+    Parameters
+    ----------
+    ts : array_like, shape (n_segments + 1,)
+        Time instants between which local interpolants are defined. Must
+        be strictly increasing or decreasing (zero segment with two points is
+        also allowed).
+    interpolants : list of DenseOutput with n_segments elements
+        Local interpolants. An i-th interpolant is assumed to be defined
+        between ``ts[i]`` and ``ts[i + 1]``.
+    alt_segment : boolean
+        Requests the alternative interpolant segment selection scheme. At each
+        solver integration point, two interpolant segments are available. The
+        default (False) and alternative (True) behaviours select the segment
+        for which the requested time corresponded to ``t`` and ``t_old``,
+        respectively. This functionality is only relevant for testing the
+        interpolants' accuracy: different integrators use different
+        construction strategies.
+
+    Attributes
+    ----------
+    t_min, t_max : float
+        Time range of the interpolation.
+    """
+    def __init__(self, ts, interpolants, alt_segment=False):
+        ts = np.asarray(ts)
+        d = np.diff(ts)
+        # The first case covers integration on zero segment.
+        if not ((ts.size == 2 and ts[0] == ts[-1])
+                or np.all(d > 0) or np.all(d < 0)):
+            raise ValueError("`ts` must be strictly increasing or decreasing.")
+
+        self.n_segments = len(interpolants)
+        if ts.shape != (self.n_segments + 1,):
+            raise ValueError("Numbers of time stamps and interpolants "
+                             "don't match.")
+
+        self.ts = ts
+        self.interpolants = interpolants
+        if ts[-1] >= ts[0]:
+            self.t_min = ts[0]
+            self.t_max = ts[-1]
+            self.ascending = True
+            self.side = "right" if alt_segment else "left"
+            self.ts_sorted = ts
+        else:
+            self.t_min = ts[-1]
+            self.t_max = ts[0]
+            self.ascending = False
+            self.side = "left" if alt_segment else "right"
+            self.ts_sorted = ts[::-1]
+
+    def _call_single(self, t):
+        # Here we preserve a certain symmetry that when t is in self.ts,
+        # if alt_segment=False, then we prioritize a segment with a lower
+        # index.
+        ind = np.searchsorted(self.ts_sorted, t, side=self.side)
+
+        segment = min(max(ind - 1, 0), self.n_segments - 1)
+        if not self.ascending:
+            segment = self.n_segments - 1 - segment
+
+        return self.interpolants[segment](t)
+
+    def __call__(self, t):
+        """Evaluate the solution.
+
+        Parameters
+        ----------
+        t : float or array_like with shape (n_points,)
+            Points to evaluate at.
+
+        Returns
+        -------
+        y : ndarray, shape (n_states,) or (n_states, n_points)
+            Computed values. Shape depends on whether `t` is a scalar or a
+            1-D array.
+        """
+        t = np.asarray(t)
+
+        if t.ndim == 0:
+            return self._call_single(t)
+
+        order = np.argsort(t)
+        reverse = np.empty_like(order)
+        reverse[order] = np.arange(order.shape[0])
+        t_sorted = t[order]
+
+        # See comment in self._call_single.
+        segments = np.searchsorted(self.ts_sorted, t_sorted, side=self.side)
+        segments -= 1
+        segments[segments < 0] = 0
+        segments[segments > self.n_segments - 1] = self.n_segments - 1
+        if not self.ascending:
+            segments = self.n_segments - 1 - segments
+
+        ys = []
+        group_start = 0
+        for segment, group in groupby(segments):
+            group_end = group_start + len(list(group))
+            y = self.interpolants[segment](t_sorted[group_start:group_end])
+            ys.append(y)
+            group_start = group_end
+
+        ys = np.hstack(ys)
+        ys = ys[:, reverse]
+
+        return ys
+
+
+NUM_JAC_DIFF_REJECT = EPS ** 0.875
+NUM_JAC_DIFF_SMALL = EPS ** 0.75
+NUM_JAC_DIFF_BIG = EPS ** 0.25
+NUM_JAC_MIN_FACTOR = 1e3 * EPS
+NUM_JAC_FACTOR_INCREASE = 10
+NUM_JAC_FACTOR_DECREASE = 0.1
+
+
+def num_jac(fun, t, y, f, threshold, factor, sparsity=None):
+    """Finite differences Jacobian approximation tailored for ODE solvers.
+
+    This function computes finite difference approximation to the Jacobian
+    matrix of `fun` with respect to `y` using forward differences.
+    The Jacobian matrix has shape (n, n) and its element (i, j) is equal to
+    ``d f_i / d y_j``.
+
+    A special feature of this function is the ability to correct the step
+    size from iteration to iteration. The main idea is to keep the finite
+    difference significantly separated from its round-off error which
+    approximately equals ``EPS * np.abs(f)``. It reduces a possibility of a
+    huge error and assures that the estimated derivative are reasonably close
+    to the true values (i.e., the finite difference approximation is at least
+    qualitatively reflects the structure of the true Jacobian).
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system implemented in a vectorized fashion.
+    t : float
+        Current time.
+    y : ndarray, shape (n,)
+        Current state.
+    f : ndarray, shape (n,)
+        Value of the right hand side at (t, y).
+    threshold : float
+        Threshold for `y` value used for computing the step size as
+        ``factor * np.maximum(np.abs(y), threshold)``. Typically, the value of
+        absolute tolerance (atol) for a solver should be passed as `threshold`.
+    factor : ndarray with shape (n,) or None
+        Factor to use for computing the step size. Pass None for the very
+        evaluation, then use the value returned from this function.
+    sparsity : tuple (structure, groups) or None
+        Sparsity structure of the Jacobian, `structure` must be csc_matrix.
+
+    Returns
+    -------
+    J : ndarray or csc_matrix, shape (n, n)
+        Jacobian matrix.
+    factor : ndarray, shape (n,)
+        Suggested `factor` for the next evaluation.
+    """
+    y = np.asarray(y)
+    n = y.shape[0]
+    if n == 0:
+        return np.empty((0, 0)), factor
+
+    if factor is None:
+        factor = np.full(n, EPS ** 0.5)
+    else:
+        factor = factor.copy()
+
+    # Direct the step as ODE dictates, hoping that such a step won't lead to
+    # a problematic region. For complex ODEs it makes sense to use the real
+    # part of f as we use steps along real axis.
+    f_sign = 2 * (np.real(f) >= 0).astype(float) - 1
+    y_scale = f_sign * np.maximum(threshold, np.abs(y))
+    h = (y + factor * y_scale) - y
+
+    # Make sure that the step is not 0 to start with. Not likely it will be
+    # executed often.
+    for i in np.nonzero(h == 0)[0]:
+        while h[i] == 0:
+            factor[i] *= 10
+            h[i] = (y[i] + factor[i] * y_scale[i]) - y[i]
+
+    if sparsity is None:
+        return _dense_num_jac(fun, t, y, f, h, factor, y_scale)
+    else:
+        structure, groups = sparsity
+        return _sparse_num_jac(fun, t, y, f, h, factor, y_scale,
+                               structure, groups)
+
+
+def _dense_num_jac(fun, t, y, f, h, factor, y_scale):
+    n = y.shape[0]
+    h_vecs = np.diag(h)
+    f_new = fun(t, y[:, None] + h_vecs)
+    diff = f_new - f[:, None]
+    max_ind = np.argmax(np.abs(diff), axis=0)
+    r = np.arange(n)
+    max_diff = np.abs(diff[max_ind, r])
+    scale = np.maximum(np.abs(f[max_ind]), np.abs(f_new[max_ind, r]))
+
+    diff_too_small = max_diff < NUM_JAC_DIFF_REJECT * scale
+    if np.any(diff_too_small):
+        ind, = np.nonzero(diff_too_small)
+        new_factor = NUM_JAC_FACTOR_INCREASE * factor[ind]
+        h_new = (y[ind] + new_factor * y_scale[ind]) - y[ind]
+        h_vecs[ind, ind] = h_new
+        f_new = fun(t, y[:, None] + h_vecs[:, ind])
+        diff_new = f_new - f[:, None]
+        max_ind = np.argmax(np.abs(diff_new), axis=0)
+        r = np.arange(ind.shape[0])
+        max_diff_new = np.abs(diff_new[max_ind, r])
+        scale_new = np.maximum(np.abs(f[max_ind]), np.abs(f_new[max_ind, r]))
+
+        update = max_diff[ind] * scale_new < max_diff_new * scale[ind]
+        if np.any(update):
+            update, = np.nonzero(update)
+            update_ind = ind[update]
+            factor[update_ind] = new_factor[update]
+            h[update_ind] = h_new[update]
+            diff[:, update_ind] = diff_new[:, update]
+            scale[update_ind] = scale_new[update]
+            max_diff[update_ind] = max_diff_new[update]
+
+    diff /= h
+
+    factor[max_diff < NUM_JAC_DIFF_SMALL * scale] *= NUM_JAC_FACTOR_INCREASE
+    factor[max_diff > NUM_JAC_DIFF_BIG * scale] *= NUM_JAC_FACTOR_DECREASE
+    factor = np.maximum(factor, NUM_JAC_MIN_FACTOR)
+
+    return diff, factor
+
+
+def _sparse_num_jac(fun, t, y, f, h, factor, y_scale, structure, groups):
+    n = y.shape[0]
+    n_groups = np.max(groups) + 1
+    h_vecs = np.empty((n_groups, n))
+    for group in range(n_groups):
+        e = np.equal(group, groups)
+        h_vecs[group] = h * e
+    h_vecs = h_vecs.T
+
+    f_new = fun(t, y[:, None] + h_vecs)
+    df = f_new - f[:, None]
+
+    i, j, _ = find(structure)
+    diff = coo_matrix((df[i, groups[j]], (i, j)), shape=(n, n)).tocsc()
+    max_ind = np.array(abs(diff).argmax(axis=0)).ravel()
+    r = np.arange(n)
+    max_diff = np.asarray(np.abs(diff[max_ind, r])).ravel()
+    scale = np.maximum(np.abs(f[max_ind]),
+                       np.abs(f_new[max_ind, groups[r]]))
+
+    diff_too_small = max_diff < NUM_JAC_DIFF_REJECT * scale
+    if np.any(diff_too_small):
+        ind, = np.nonzero(diff_too_small)
+        new_factor = NUM_JAC_FACTOR_INCREASE * factor[ind]
+        h_new = (y[ind] + new_factor * y_scale[ind]) - y[ind]
+        h_new_all = np.zeros(n)
+        h_new_all[ind] = h_new
+
+        groups_unique = np.unique(groups[ind])
+        groups_map = np.empty(n_groups, dtype=int)
+        h_vecs = np.empty((groups_unique.shape[0], n))
+        for k, group in enumerate(groups_unique):
+            e = np.equal(group, groups)
+            h_vecs[k] = h_new_all * e
+            groups_map[group] = k
+        h_vecs = h_vecs.T
+
+        f_new = fun(t, y[:, None] + h_vecs)
+        df = f_new - f[:, None]
+        i, j, _ = find(structure[:, ind])
+        diff_new = coo_matrix((df[i, groups_map[groups[ind[j]]]],
+                               (i, j)), shape=(n, ind.shape[0])).tocsc()
+
+        max_ind_new = np.array(abs(diff_new).argmax(axis=0)).ravel()
+        r = np.arange(ind.shape[0])
+        max_diff_new = np.asarray(np.abs(diff_new[max_ind_new, r])).ravel()
+        scale_new = np.maximum(
+            np.abs(f[max_ind_new]),
+            np.abs(f_new[max_ind_new, groups_map[groups[ind]]]))
+
+        update = max_diff[ind] * scale_new < max_diff_new * scale[ind]
+        if np.any(update):
+            update, = np.nonzero(update)
+            update_ind = ind[update]
+            factor[update_ind] = new_factor[update]
+            h[update_ind] = h_new[update]
+            diff[:, update_ind] = diff_new[:, update]
+            scale[update_ind] = scale_new[update]
+            max_diff[update_ind] = max_diff_new[update]
+
+    diff.data /= np.repeat(h, np.diff(diff.indptr))
+
+    factor[max_diff < NUM_JAC_DIFF_SMALL * scale] *= NUM_JAC_FACTOR_INCREASE
+    factor[max_diff > NUM_JAC_DIFF_BIG * scale] *= NUM_JAC_FACTOR_DECREASE
+    factor = np.maximum(factor, NUM_JAC_MIN_FACTOR)
+
+    return diff, factor

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/dop853_coefficients.py

@@ -0,0 +1,193 @@
+import numpy as np
+
+N_STAGES = 12
+N_STAGES_EXTENDED = 16
+INTERPOLATOR_POWER = 7
+
+C = np.array([0.0,
+              0.526001519587677318785587544488e-01,
+              0.789002279381515978178381316732e-01,
+              0.118350341907227396726757197510,
+              0.281649658092772603273242802490,
+              0.333333333333333333333333333333,
+              0.25,
+              0.307692307692307692307692307692,
+              0.651282051282051282051282051282,
+              0.6,
+              0.857142857142857142857142857142,
+              1.0,
+              1.0,
+              0.1,
+              0.2,
+              0.777777777777777777777777777778])
+
+A = np.zeros((N_STAGES_EXTENDED, N_STAGES_EXTENDED))
+A[1, 0] = 5.26001519587677318785587544488e-2
+
+A[2, 0] = 1.97250569845378994544595329183e-2
+A[2, 1] = 5.91751709536136983633785987549e-2
+
+A[3, 0] = 2.95875854768068491816892993775e-2
+A[3, 2] = 8.87627564304205475450678981324e-2
+
+A[4, 0] = 2.41365134159266685502369798665e-1
+A[4, 2] = -8.84549479328286085344864962717e-1
+A[4, 3] = 9.24834003261792003115737966543e-1
+
+A[5, 0] = 3.7037037037037037037037037037e-2
+A[5, 3] = 1.70828608729473871279604482173e-1
+A[5, 4] = 1.25467687566822425016691814123e-1
+
+A[6, 0] = 3.7109375e-2
+A[6, 3] = 1.70252211019544039314978060272e-1
+A[6, 4] = 6.02165389804559606850219397283e-2
+A[6, 5] = -1.7578125e-2
+
+A[7, 0] = 3.70920001185047927108779319836e-2
+A[7, 3] = 1.70383925712239993810214054705e-1
+A[7, 4] = 1.07262030446373284651809199168e-1
+A[7, 5] = -1.53194377486244017527936158236e-2
+A[7, 6] = 8.27378916381402288758473766002e-3
+
+A[8, 0] = 6.24110958716075717114429577812e-1
+A[8, 3] = -3.36089262944694129406857109825
+A[8, 4] = -8.68219346841726006818189891453e-1
+A[8, 5] = 2.75920996994467083049415600797e1
+A[8, 6] = 2.01540675504778934086186788979e1
+A[8, 7] = -4.34898841810699588477366255144e1
+
+A[9, 0] = 4.77662536438264365890433908527e-1
+A[9, 3] = -2.48811461997166764192642586468
+A[9, 4] = -5.90290826836842996371446475743e-1
+A[9, 5] = 2.12300514481811942347288949897e1
+A[9, 6] = 1.52792336328824235832596922938e1
+A[9, 7] = -3.32882109689848629194453265587e1
+A[9, 8] = -2.03312017085086261358222928593e-2
+
+A[10, 0] = -9.3714243008598732571704021658e-1
+A[10, 3] = 5.18637242884406370830023853209
+A[10, 4] = 1.09143734899672957818500254654
+A[10, 5] = -8.14978701074692612513997267357
+A[10, 6] = -1.85200656599969598641566180701e1
+A[10, 7] = 2.27394870993505042818970056734e1
+A[10, 8] = 2.49360555267965238987089396762
+A[10, 9] = -3.0467644718982195003823669022
+
+A[11, 0] = 2.27331014751653820792359768449
+A[11, 3] = -1.05344954667372501984066689879e1
+A[11, 4] = -2.00087205822486249909675718444
+A[11, 5] = -1.79589318631187989172765950534e1
+A[11, 6] = 2.79488845294199600508499808837e1
+A[11, 7] = -2.85899827713502369474065508674
+A[11, 8] = -8.87285693353062954433549289258
+A[11, 9] = 1.23605671757943030647266201528e1
+A[11, 10] = 6.43392746015763530355970484046e-1
+
+A[12, 0] = 5.42937341165687622380535766363e-2
+A[12, 5] = 4.45031289275240888144113950566
+A[12, 6] = 1.89151789931450038304281599044
+A[12, 7] = -5.8012039600105847814672114227
+A[12, 8] = 3.1116436695781989440891606237e-1
+A[12, 9] = -1.52160949662516078556178806805e-1
+A[12, 10] = 2.01365400804030348374776537501e-1
+A[12, 11] = 4.47106157277725905176885569043e-2
+
+A[13, 0] = 5.61675022830479523392909219681e-2
+A[13, 6] = 2.53500210216624811088794765333e-1
+A[13, 7] = -2.46239037470802489917441475441e-1
+A[13, 8] = -1.24191423263816360469010140626e-1
+A[13, 9] = 1.5329179827876569731206322685e-1
+A[13, 10] = 8.20105229563468988491666602057e-3
+A[13, 11] = 7.56789766054569976138603589584e-3
+A[13, 12] = -8.298e-3
+
+A[14, 0] = 3.18346481635021405060768473261e-2
+A[14, 5] = 2.83009096723667755288322961402e-2
+A[14, 6] = 5.35419883074385676223797384372e-2
+A[14, 7] = -5.49237485713909884646569340306e-2
+A[14, 10] = -1.08347328697249322858509316994e-4
+A[14, 11] = 3.82571090835658412954920192323e-4
+A[14, 12] = -3.40465008687404560802977114492e-4
+A[14, 13] = 1.41312443674632500278074618366e-1
+
+A[15, 0] = -4.28896301583791923408573538692e-1
+A[15, 5] = -4.69762141536116384314449447206
+A[15, 6] = 7.68342119606259904184240953878
+A[15, 7] = 4.06898981839711007970213554331
+A[15, 8] = 3.56727187455281109270669543021e-1
+A[15, 12] = -1.39902416515901462129418009734e-3
+A[15, 13] = 2.9475147891527723389556272149
+A[15, 14] = -9.15095847217987001081870187138
+
+
+B = A[N_STAGES, :N_STAGES]
+
+E3 = np.zeros(N_STAGES + 1)
+E3[:-1] = B.copy()
+E3[0] -= 0.244094488188976377952755905512
+E3[8] -= 0.733846688281611857341361741547
+E3[11] -= 0.220588235294117647058823529412e-1
+
+E5 = np.zeros(N_STAGES + 1)
+E5[0] = 0.1312004499419488073250102996e-1
+E5[5] = -0.1225156446376204440720569753e+1
+E5[6] = -0.4957589496572501915214079952
+E5[7] = 0.1664377182454986536961530415e+1
+E5[8] = -0.3503288487499736816886487290
+E5[9] = 0.3341791187130174790297318841
+E5[10] = 0.8192320648511571246570742613e-1
+E5[11] = -0.2235530786388629525884427845e-1
+
+# First 3 coefficients are computed separately.
+D = np.zeros((INTERPOLATOR_POWER - 3, N_STAGES_EXTENDED))
+D[0, 0] = -0.84289382761090128651353491142e+1
+D[0, 5] = 0.56671495351937776962531783590
+D[0, 6] = -0.30689499459498916912797304727e+1
+D[0, 7] = 0.23846676565120698287728149680e+1
+D[0, 8] = 0.21170345824450282767155149946e+1
+D[0, 9] = -0.87139158377797299206789907490
+D[0, 10] = 0.22404374302607882758541771650e+1
+D[0, 11] = 0.63157877876946881815570249290
+D[0, 12] = -0.88990336451333310820698117400e-1
+D[0, 13] = 0.18148505520854727256656404962e+2
+D[0, 14] = -0.91946323924783554000451984436e+1
+D[0, 15] = -0.44360363875948939664310572000e+1
+
+D[1, 0] = 0.10427508642579134603413151009e+2
+D[1, 5] = 0.24228349177525818288430175319e+3
+D[1, 6] = 0.16520045171727028198505394887e+3
+D[1, 7] = -0.37454675472269020279518312152e+3
+D[1, 8] = -0.22113666853125306036270938578e+2
+D[1, 9] = 0.77334326684722638389603898808e+1
+D[1, 10] = -0.30674084731089398182061213626e+2
+D[1, 11] = -0.93321305264302278729567221706e+1
+D[1, 12] = 0.15697238121770843886131091075e+2
+D[1, 13] = -0.31139403219565177677282850411e+2
+D[1, 14] = -0.93529243588444783865713862664e+1
+D[1, 15] = 0.35816841486394083752465898540e+2
+
+D[2, 0] = 0.19985053242002433820987653617e+2
+D[2, 5] = -0.38703730874935176555105901742e+3
+D[2, 6] = -0.18917813819516756882830838328e+3
+D[2, 7] = 0.52780815920542364900561016686e+3
+D[2, 8] = -0.11573902539959630126141871134e+2
+D[2, 9] = 0.68812326946963000169666922661e+1
+D[2, 10] = -0.10006050966910838403183860980e+1
+D[2, 11] = 0.77771377980534432092869265740
+D[2, 12] = -0.27782057523535084065932004339e+1
+D[2, 13] = -0.60196695231264120758267380846e+2
+D[2, 14] = 0.84320405506677161018159903784e+2
+D[2, 15] = 0.11992291136182789328035130030e+2
+
+D[3, 0] = -0.25693933462703749003312586129e+2
+D[3, 5] = -0.15418974869023643374053993627e+3
+D[3, 6] = -0.23152937917604549567536039109e+3
+D[3, 7] = 0.35763911791061412378285349910e+3
+D[3, 8] = 0.93405324183624310003907691704e+2
+D[3, 9] = -0.37458323136451633156875139351e+2
+D[3, 10] = 0.10409964950896230045147246184e+3
+D[3, 11] = 0.29840293426660503123344363579e+2
+D[3, 12] = -0.43533456590011143754432175058e+2
+D[3, 13] = 0.96324553959188282948394950600e+2
+D[3, 14] = -0.39177261675615439165231486172e+2
+D[3, 15] = -0.14972683625798562581422125276e+3

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/ivp.py

@@ -0,0 +1,748 @@
+import inspect
+import numpy as np
+from .bdf import BDF
+from .radau import Radau
+from .rk import RK23, RK45, DOP853
+from .lsoda import LSODA
+from scipy.optimize import OptimizeResult
+from .common import EPS, OdeSolution
+from .base import OdeSolver
+
+
+METHODS = {'RK23': RK23,
+           'RK45': RK45,
+           'DOP853': DOP853,
+           'Radau': Radau,
+           'BDF': BDF,
+           'LSODA': LSODA}
+
+
+MESSAGES = {0: "The solver successfully reached the end of the integration interval.",
+            1: "A termination event occurred."}
+
+
+class OdeResult(OptimizeResult):
+    pass
+
+
+def prepare_events(events):
+    """Standardize event functions and extract attributes."""
+    if callable(events):
+        events = (events,)
+
+    max_events = np.empty(len(events))
+    direction = np.empty(len(events))
+    for i, event in enumerate(events):
+        terminal = getattr(event, 'terminal', None)
+        direction[i] = getattr(event, 'direction', 0)
+
+        message = ('The `terminal` attribute of each event '
+                   'must be a boolean or positive integer.')
+        if terminal is None or terminal == 0:
+            max_events[i] = np.inf
+        elif int(terminal) == terminal and terminal > 0:
+            max_events[i] = terminal
+        else:
+            raise ValueError(message)
+
+    return events, max_events, direction
+
+
+def solve_event_equation(event, sol, t_old, t):
+    """Solve an equation corresponding to an ODE event.
+
+    The equation is ``event(t, y(t)) = 0``, here ``y(t)`` is known from an
+    ODE solver using some sort of interpolation. It is solved by
+    `scipy.optimize.brentq` with xtol=atol=4*EPS.
+
+    Parameters
+    ----------
+    event : callable
+        Function ``event(t, y)``.
+    sol : callable
+        Function ``sol(t)`` which evaluates an ODE solution between `t_old`
+        and  `t`.
+    t_old, t : float
+        Previous and new values of time. They will be used as a bracketing
+        interval.
+
+    Returns
+    -------
+    root : float
+        Found solution.
+    """
+    from scipy.optimize import brentq
+    return brentq(lambda t: event(t, sol(t)), t_old, t,
+                  xtol=4 * EPS, rtol=4 * EPS)
+
+
+def handle_events(sol, events, active_events, event_count, max_events,
+                  t_old, t):
+    """Helper function to handle events.
+
+    Parameters
+    ----------
+    sol : DenseOutput
+        Function ``sol(t)`` which evaluates an ODE solution between `t_old`
+        and  `t`.
+    events : list of callables, length n_events
+        Event functions with signatures ``event(t, y)``.
+    active_events : ndarray
+        Indices of events which occurred.
+    event_count : ndarray
+        Current number of occurrences for each event.
+    max_events : ndarray, shape (n_events,)
+        Number of occurrences allowed for each event before integration
+        termination is issued.
+    t_old, t : float
+        Previous and new values of time.
+
+    Returns
+    -------
+    root_indices : ndarray
+        Indices of events which take zero between `t_old` and `t` and before
+        a possible termination.
+    roots : ndarray
+        Values of t at which events occurred.
+    terminate : bool
+        Whether a terminal event occurred.
+    """
+    roots = [solve_event_equation(events[event_index], sol, t_old, t)
+             for event_index in active_events]
+
+    roots = np.asarray(roots)
+
+    if np.any(event_count[active_events] >= max_events[active_events]):
+        if t > t_old:
+            order = np.argsort(roots)
+        else:
+            order = np.argsort(-roots)
+        active_events = active_events[order]
+        roots = roots[order]
+        t = np.nonzero(event_count[active_events]
+                       >= max_events[active_events])[0][0]
+        active_events = active_events[:t + 1]
+        roots = roots[:t + 1]
+        terminate = True
+    else:
+        terminate = False
+
+    return active_events, roots, terminate
+
+
+def find_active_events(g, g_new, direction):
+    """Find which event occurred during an integration step.
+
+    Parameters
+    ----------
+    g, g_new : array_like, shape (n_events,)
+        Values of event functions at a current and next points.
+    direction : ndarray, shape (n_events,)
+        Event "direction" according to the definition in `solve_ivp`.
+
+    Returns
+    -------
+    active_events : ndarray
+        Indices of events which occurred during the step.
+    """
+    g, g_new = np.asarray(g), np.asarray(g_new)
+    up = (g <= 0) & (g_new >= 0)
+    down = (g >= 0) & (g_new <= 0)
+    either = up | down
+    mask = (up & (direction > 0) |
+            down & (direction < 0) |
+            either & (direction == 0))
+
+    return np.nonzero(mask)[0]
+
+
+def solve_ivp(fun, t_span, y0, method='RK45', t_eval=None, dense_output=False,
+              events=None, vectorized=False, args=None, **options):
+    """Solve an initial value problem for a system of ODEs.
+
+    This function numerically integrates a system of ordinary differential
+    equations given an initial value::
+
+        dy / dt = f(t, y)
+        y(t0) = y0
+
+    Here t is a 1-D independent variable (time), y(t) is an
+    N-D vector-valued function (state), and an N-D
+    vector-valued function f(t, y) determines the differential equations.
+    The goal is to find y(t) approximately satisfying the differential
+    equations, given an initial value y(t0)=y0.
+
+    Some of the solvers support integration in the complex domain, but note
+    that for stiff ODE solvers, the right-hand side must be
+    complex-differentiable (satisfy Cauchy-Riemann equations [11]_).
+    To solve a problem in the complex domain, pass y0 with a complex data type.
+    Another option always available is to rewrite your problem for real and
+    imaginary parts separately.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system: the time derivative of the state ``y``
+        at time ``t``. The calling signature is ``fun(t, y)``, where ``t`` is a
+        scalar and ``y`` is an ndarray with ``len(y) = len(y0)``. Additional
+        arguments need to be passed if ``args`` is used (see documentation of
+        ``args`` argument). ``fun`` must return an array of the same shape as
+        ``y``. See `vectorized` for more information.
+    t_span : 2-member sequence
+        Interval of integration (t0, tf). The solver starts with t=t0 and
+        integrates until it reaches t=tf. Both t0 and tf must be floats
+        or values interpretable by the float conversion function.
+    y0 : array_like, shape (n,)
+        Initial state. For problems in the complex domain, pass `y0` with a
+        complex data type (even if the initial value is purely real).
+    method : string or `OdeSolver`, optional
+        Integration method to use:
+
+            * 'RK45' (default): Explicit Runge-Kutta method of order 5(4) [1]_.
+              The error is controlled assuming accuracy of the fourth-order
+              method, but steps are taken using the fifth-order accurate
+              formula (local extrapolation is done). A quartic interpolation
+              polynomial is used for the dense output [2]_. Can be applied in
+              the complex domain.
+            * 'RK23': Explicit Runge-Kutta method of order 3(2) [3]_. The error
+              is controlled assuming accuracy of the second-order method, but
+              steps are taken using the third-order accurate formula (local
+              extrapolation is done). A cubic Hermite polynomial is used for the
+              dense output. Can be applied in the complex domain.
+            * 'DOP853': Explicit Runge-Kutta method of order 8 [13]_.
+              Python implementation of the "DOP853" algorithm originally
+              written in Fortran [14]_. A 7-th order interpolation polynomial
+              accurate to 7-th order is used for the dense output.
+              Can be applied in the complex domain.
+            * 'Radau': Implicit Runge-Kutta method of the Radau IIA family of
+              order 5 [4]_. The error is controlled with a third-order accurate
+              embedded formula. A cubic polynomial which satisfies the
+              collocation conditions is used for the dense output.
+            * 'BDF': Implicit multi-step variable-order (1 to 5) method based
+              on a backward differentiation formula for the derivative
+              approximation [5]_. The implementation follows the one described
+              in [6]_. A quasi-constant step scheme is used and accuracy is
+              enhanced using the NDF modification. Can be applied in the
+              complex domain.
+            * 'LSODA': Adams/BDF method with automatic stiffness detection and
+              switching [7]_, [8]_. This is a wrapper of the Fortran solver
+              from ODEPACK.
+
+        Explicit Runge-Kutta methods ('RK23', 'RK45', 'DOP853') should be used
+        for non-stiff problems and implicit methods ('Radau', 'BDF') for
+        stiff problems [9]_. Among Runge-Kutta methods, 'DOP853' is recommended
+        for solving with high precision (low values of `rtol` and `atol`).
+
+        If not sure, first try to run 'RK45'. If it makes unusually many
+        iterations, diverges, or fails, your problem is likely to be stiff and
+        you should use 'Radau' or 'BDF'. 'LSODA' can also be a good universal
+        choice, but it might be somewhat less convenient to work with as it
+        wraps old Fortran code.
+
+        You can also pass an arbitrary class derived from `OdeSolver` which
+        implements the solver.
+    t_eval : array_like or None, optional
+        Times at which to store the computed solution, must be sorted and lie
+        within `t_span`. If None (default), use points selected by the solver.
+    dense_output : bool, optional
+        Whether to compute a continuous solution. Default is False.
+    events : callable, or list of callables, optional
+        Events to track. If None (default), no events will be tracked.
+        Each event occurs at the zeros of a continuous function of time and
+        state. Each function must have the signature ``event(t, y)`` where
+        additional argument have to be passed if ``args`` is used (see
+        documentation of ``args`` argument). Each function must return a
+        float. The solver will find an accurate value of `t` at which
+        ``event(t, y(t)) = 0`` using a root-finding algorithm. By default,
+        all zeros will be found. The solver looks for a sign change over
+        each step, so if multiple zero crossings occur within one step,
+        events may be missed. Additionally each `event` function might
+        have the following attributes:
+
+            terminal: bool or int, optional
+                When boolean, whether to terminate integration if this event occurs.
+                When integral, termination occurs after the specified the number of
+                occurences of this event.
+                Implicitly False if not assigned.
+            direction: float, optional
+                Direction of a zero crossing. If `direction` is positive,
+                `event` will only trigger when going from negative to positive,
+                and vice versa if `direction` is negative. If 0, then either
+                direction will trigger event. Implicitly 0 if not assigned.
+
+        You can assign attributes like ``event.terminal = True`` to any
+        function in Python.
+    vectorized : bool, optional
+        Whether `fun` can be called in a vectorized fashion. Default is False.
+
+        If ``vectorized`` is False, `fun` will always be called with ``y`` of
+        shape ``(n,)``, where ``n = len(y0)``.
+
+        If ``vectorized`` is True, `fun` may be called with ``y`` of shape
+        ``(n, k)``, where ``k`` is an integer. In this case, `fun` must behave
+        such that ``fun(t, y)[:, i] == fun(t, y[:, i])`` (i.e. each column of
+        the returned array is the time derivative of the state corresponding
+        with a column of ``y``).
+
+        Setting ``vectorized=True`` allows for faster finite difference
+        approximation of the Jacobian by methods 'Radau' and 'BDF', but
+        will result in slower execution for other methods and for 'Radau' and
+        'BDF' in some circumstances (e.g. small ``len(y0)``).
+    args : tuple, optional
+        Additional arguments to pass to the user-defined functions.  If given,
+        the additional arguments are passed to all user-defined functions.
+        So if, for example, `fun` has the signature ``fun(t, y, a, b, c)``,
+        then `jac` (if given) and any event functions must have the same
+        signature, and `args` must be a tuple of length 3.
+    **options
+        Options passed to a chosen solver. All options available for already
+        implemented solvers are listed below.
+    first_step : float or None, optional
+        Initial step size. Default is `None` which means that the algorithm
+        should choose.
+    max_step : float, optional
+        Maximum allowed step size. Default is np.inf, i.e., the step size is not
+        bounded and determined solely by the solver.
+    rtol, atol : float or array_like, optional
+        Relative and absolute tolerances. The solver keeps the local error
+        estimates less than ``atol + rtol * abs(y)``. Here `rtol` controls a
+        relative accuracy (number of correct digits), while `atol` controls
+        absolute accuracy (number of correct decimal places). To achieve the
+        desired `rtol`, set `atol` to be smaller than the smallest value that
+        can be expected from ``rtol * abs(y)`` so that `rtol` dominates the
+        allowable error. If `atol` is larger than ``rtol * abs(y)`` the
+        number of correct digits is not guaranteed. Conversely, to achieve the
+        desired `atol` set `rtol` such that ``rtol * abs(y)`` is always smaller
+        than `atol`. If components of y have different scales, it might be
+        beneficial to set different `atol` values for different components by
+        passing array_like with shape (n,) for `atol`. Default values are
+        1e-3 for `rtol` and 1e-6 for `atol`.
+    jac : array_like, sparse_matrix, callable or None, optional
+        Jacobian matrix of the right-hand side of the system with respect
+        to y, required by the 'Radau', 'BDF' and 'LSODA' method. The
+        Jacobian matrix has shape (n, n) and its element (i, j) is equal to
+        ``d f_i / d y_j``.  There are three ways to define the Jacobian:
+
+            * If array_like or sparse_matrix, the Jacobian is assumed to
+              be constant. Not supported by 'LSODA'.
+            * If callable, the Jacobian is assumed to depend on both
+              t and y; it will be called as ``jac(t, y)``, as necessary.
+              Additional arguments have to be passed if ``args`` is
+              used (see documentation of ``args`` argument).
+              For 'Radau' and 'BDF' methods, the return value might be a
+              sparse matrix.
+            * If None (default), the Jacobian will be approximated by
+              finite differences.
+
+        It is generally recommended to provide the Jacobian rather than
+        relying on a finite-difference approximation.
+    jac_sparsity : array_like, sparse matrix or None, optional
+        Defines a sparsity structure of the Jacobian matrix for a finite-
+        difference approximation. Its shape must be (n, n). This argument
+        is ignored if `jac` is not `None`. If the Jacobian has only few
+        non-zero elements in *each* row, providing the sparsity structure
+        will greatly speed up the computations [10]_. A zero entry means that
+        a corresponding element in the Jacobian is always zero. If None
+        (default), the Jacobian is assumed to be dense.
+        Not supported by 'LSODA', see `lband` and `uband` instead.
+    lband, uband : int or None, optional
+        Parameters defining the bandwidth of the Jacobian for the 'LSODA'
+        method, i.e., ``jac[i, j] != 0 only for i - lband <= j <= i + uband``.
+        Default is None. Setting these requires your jac routine to return the
+        Jacobian in the packed format: the returned array must have ``n``
+        columns and ``uband + lband + 1`` rows in which Jacobian diagonals are
+        written. Specifically ``jac_packed[uband + i - j , j] = jac[i, j]``.
+        The same format is used in `scipy.linalg.solve_banded` (check for an
+        illustration).  These parameters can be also used with ``jac=None`` to
+        reduce the number of Jacobian elements estimated by finite differences.
+    min_step : float, optional
+        The minimum allowed step size for 'LSODA' method.
+        By default `min_step` is zero.
+
+    Returns
+    -------
+    Bunch object with the following fields defined:
+    t : ndarray, shape (n_points,)
+        Time points.
+    y : ndarray, shape (n, n_points)
+        Values of the solution at `t`.
+    sol : `OdeSolution` or None
+        Found solution as `OdeSolution` instance; None if `dense_output` was
+        set to False.
+    t_events : list of ndarray or None
+        Contains for each event type a list of arrays at which an event of
+        that type event was detected. None if `events` was None.
+    y_events : list of ndarray or None
+        For each value of `t_events`, the corresponding value of the solution.
+        None if `events` was None.
+    nfev : int
+        Number of evaluations of the right-hand side.
+    njev : int
+        Number of evaluations of the Jacobian.
+    nlu : int
+        Number of LU decompositions.
+    status : int
+        Reason for algorithm termination:
+
+            * -1: Integration step failed.
+            *  0: The solver successfully reached the end of `tspan`.
+            *  1: A termination event occurred.
+
+    message : string
+        Human-readable description of the termination reason.
+    success : bool
+        True if the solver reached the interval end or a termination event
+        occurred (``status >= 0``).
+
+    References
+    ----------
+    .. [1] J. R. Dormand, P. J. Prince, "A family of embedded Runge-Kutta
+           formulae", Journal of Computational and Applied Mathematics, Vol. 6,
+           No. 1, pp. 19-26, 1980.
+    .. [2] L. W. Shampine, "Some Practical Runge-Kutta Formulas", Mathematics
+           of Computation,, Vol. 46, No. 173, pp. 135-150, 1986.
+    .. [3] P. Bogacki, L.F. Shampine, "A 3(2) Pair of Runge-Kutta Formulas",
+           Appl. Math. Lett. Vol. 2, No. 4. pp. 321-325, 1989.
+    .. [4] E. Hairer, G. Wanner, "Solving Ordinary Differential Equations II:
+           Stiff and Differential-Algebraic Problems", Sec. IV.8.
+    .. [5] `Backward Differentiation Formula
+            <https://en.wikipedia.org/wiki/Backward_differentiation_formula>`_
+            on Wikipedia.
+    .. [6] L. F. Shampine, M. W. Reichelt, "THE MATLAB ODE SUITE", SIAM J. SCI.
+           COMPUTE., Vol. 18, No. 1, pp. 1-22, January 1997.
+    .. [7] A. C. Hindmarsh, "ODEPACK, A Systematized Collection of ODE
+           Solvers," IMACS Transactions on Scientific Computation, Vol 1.,
+           pp. 55-64, 1983.
+    .. [8] L. Petzold, "Automatic selection of methods for solving stiff and
+           nonstiff systems of ordinary differential equations", SIAM Journal
+           on Scientific and Statistical Computing, Vol. 4, No. 1, pp. 136-148,
+           1983.
+    .. [9] `Stiff equation <https://en.wikipedia.org/wiki/Stiff_equation>`_ on
+           Wikipedia.
+    .. [10] A. Curtis, M. J. D. Powell, and J. Reid, "On the estimation of
+            sparse Jacobian matrices", Journal of the Institute of Mathematics
+            and its Applications, 13, pp. 117-120, 1974.
+    .. [11] `Cauchy-Riemann equations
+             <https://en.wikipedia.org/wiki/Cauchy-Riemann_equations>`_ on
+             Wikipedia.
+    .. [12] `Lotka-Volterra equations
+            <https://en.wikipedia.org/wiki/Lotka%E2%80%93Volterra_equations>`_
+            on Wikipedia.
+    .. [13] E. Hairer, S. P. Norsett G. Wanner, "Solving Ordinary Differential
+            Equations I: Nonstiff Problems", Sec. II.
+    .. [14] `Page with original Fortran code of DOP853
+            <http://www.unige.ch/~hairer/software.html>`_.
+
+    Examples
+    --------
+    Basic exponential decay showing automatically chosen time points.
+
+    >>> import numpy as np
+    >>> from scipy.integrate import solve_ivp
+    >>> def exponential_decay(t, y): return -0.5 * y
+    >>> sol = solve_ivp(exponential_decay, [0, 10], [2, 4, 8])
+    >>> print(sol.t)
+    [ 0.          0.11487653  1.26364188  3.06061781  4.81611105  6.57445806
+      8.33328988 10.        ]
+    >>> print(sol.y)
+    [[2.         1.88836035 1.06327177 0.43319312 0.18017253 0.07483045
+      0.03107158 0.01350781]
+     [4.         3.7767207  2.12654355 0.86638624 0.36034507 0.14966091
+      0.06214316 0.02701561]
+     [8.         7.5534414  4.25308709 1.73277247 0.72069014 0.29932181
+      0.12428631 0.05403123]]
+
+    Specifying points where the solution is desired.
+
+    >>> sol = solve_ivp(exponential_decay, [0, 10], [2, 4, 8],
+    ...                 t_eval=[0, 1, 2, 4, 10])
+    >>> print(sol.t)
+    [ 0  1  2  4 10]
+    >>> print(sol.y)
+    [[2.         1.21305369 0.73534021 0.27066736 0.01350938]
+     [4.         2.42610739 1.47068043 0.54133472 0.02701876]
+     [8.         4.85221478 2.94136085 1.08266944 0.05403753]]
+
+    Cannon fired upward with terminal event upon impact. The ``terminal`` and
+    ``direction`` fields of an event are applied by monkey patching a function.
+    Here ``y[0]`` is position and ``y[1]`` is velocity. The projectile starts
+    at position 0 with velocity +10. Note that the integration never reaches
+    t=100 because the event is terminal.
+
+    >>> def upward_cannon(t, y): return [y[1], -0.5]
+    >>> def hit_ground(t, y): return y[0]
+    >>> hit_ground.terminal = True
+    >>> hit_ground.direction = -1
+    >>> sol = solve_ivp(upward_cannon, [0, 100], [0, 10], events=hit_ground)
+    >>> print(sol.t_events)
+    [array([40.])]
+    >>> print(sol.t)
+    [0.00000000e+00 9.99900010e-05 1.09989001e-03 1.10988901e-02
+     1.11088891e-01 1.11098890e+00 1.11099890e+01 4.00000000e+01]
+
+    Use `dense_output` and `events` to find position, which is 100, at the apex
+    of the cannonball's trajectory. Apex is not defined as terminal, so both
+    apex and hit_ground are found. There is no information at t=20, so the sol
+    attribute is used to evaluate the solution. The sol attribute is returned
+    by setting ``dense_output=True``. Alternatively, the `y_events` attribute
+    can be used to access the solution at the time of the event.
+
+    >>> def apex(t, y): return y[1]
+    >>> sol = solve_ivp(upward_cannon, [0, 100], [0, 10],
+    ...                 events=(hit_ground, apex), dense_output=True)
+    >>> print(sol.t_events)
+    [array([40.]), array([20.])]
+    >>> print(sol.t)
+    [0.00000000e+00 9.99900010e-05 1.09989001e-03 1.10988901e-02
+     1.11088891e-01 1.11098890e+00 1.11099890e+01 4.00000000e+01]
+    >>> print(sol.sol(sol.t_events[1][0]))
+    [100.   0.]
+    >>> print(sol.y_events)
+    [array([[-5.68434189e-14, -1.00000000e+01]]),
+     array([[1.00000000e+02, 1.77635684e-15]])]
+
+    As an example of a system with additional parameters, we'll implement
+    the Lotka-Volterra equations [12]_.
+
+    >>> def lotkavolterra(t, z, a, b, c, d):
+    ...     x, y = z
+    ...     return [a*x - b*x*y, -c*y + d*x*y]
+    ...
+
+    We pass in the parameter values a=1.5, b=1, c=3 and d=1 with the `args`
+    argument.
+
+    >>> sol = solve_ivp(lotkavolterra, [0, 15], [10, 5], args=(1.5, 1, 3, 1),
+    ...                 dense_output=True)
+
+    Compute a dense solution and plot it.
+
+    >>> t = np.linspace(0, 15, 300)
+    >>> z = sol.sol(t)
+    >>> import matplotlib.pyplot as plt
+    >>> plt.plot(t, z.T)
+    >>> plt.xlabel('t')
+    >>> plt.legend(['x', 'y'], shadow=True)
+    >>> plt.title('Lotka-Volterra System')
+    >>> plt.show()
+
+    A couple examples of using solve_ivp to solve the differential
+    equation ``y' = Ay`` with complex matrix ``A``.
+
+    >>> A = np.array([[-0.25 + 0.14j, 0, 0.33 + 0.44j],
+    ...               [0.25 + 0.58j, -0.2 + 0.14j, 0],
+    ...               [0, 0.2 + 0.4j, -0.1 + 0.97j]])
+
+    Solving an IVP with ``A`` from above and ``y`` as 3x1 vector:
+
+    >>> def deriv_vec(t, y):
+    ...     return A @ y
+    >>> result = solve_ivp(deriv_vec, [0, 25],
+    ...                    np.array([10 + 0j, 20 + 0j, 30 + 0j]),
+    ...                    t_eval=np.linspace(0, 25, 101))
+    >>> print(result.y[:, 0])
+    [10.+0.j 20.+0.j 30.+0.j]
+    >>> print(result.y[:, -1])
+    [18.46291039+45.25653651j 10.01569306+36.23293216j
+     -4.98662741+80.07360388j]
+
+    Solving an IVP with ``A`` from above with ``y`` as 3x3 matrix :
+
+    >>> def deriv_mat(t, y):
+    ...     return (A @ y.reshape(3, 3)).flatten()
+    >>> y0 = np.array([[2 + 0j, 3 + 0j, 4 + 0j],
+    ...                [5 + 0j, 6 + 0j, 7 + 0j],
+    ...                [9 + 0j, 34 + 0j, 78 + 0j]])
+
+    >>> result = solve_ivp(deriv_mat, [0, 25], y0.flatten(),
+    ...                    t_eval=np.linspace(0, 25, 101))
+    >>> print(result.y[:, 0].reshape(3, 3))
+    [[ 2.+0.j  3.+0.j  4.+0.j]
+     [ 5.+0.j  6.+0.j  7.+0.j]
+     [ 9.+0.j 34.+0.j 78.+0.j]]
+    >>> print(result.y[:, -1].reshape(3, 3))
+    [[  5.67451179 +12.07938445j  17.2888073  +31.03278837j
+        37.83405768 +63.25138759j]
+     [  3.39949503 +11.82123994j  21.32530996 +44.88668871j
+        53.17531184+103.80400411j]
+     [ -2.26105874 +22.19277664j -15.1255713  +70.19616341j
+       -38.34616845+153.29039931j]]
+
+
+    """
+    if method not in METHODS and not (
+            inspect.isclass(method) and issubclass(method, OdeSolver)):
+        raise ValueError(f"`method` must be one of {METHODS} or OdeSolver class.")
+
+    t0, tf = map(float, t_span)
+
+    if args is not None:
+        # Wrap the user's fun (and jac, if given) in lambdas to hide the
+        # additional parameters.  Pass in the original fun as a keyword
+        # argument to keep it in the scope of the lambda.
+        try:
+            _ = [*(args)]
+        except TypeError as exp:
+            suggestion_tuple = (
+                "Supplied 'args' cannot be unpacked. Please supply `args`"
+                f" as a tuple (e.g. `args=({args},)`)"
+            )
+            raise TypeError(suggestion_tuple) from exp
+
+        def fun(t, x, fun=fun):
+            return fun(t, x, *args)
+        jac = options.get('jac')
+        if callable(jac):
+            options['jac'] = lambda t, x: jac(t, x, *args)
+
+    if t_eval is not None:
+        t_eval = np.asarray(t_eval)
+        if t_eval.ndim != 1:
+            raise ValueError("`t_eval` must be 1-dimensional.")
+
+        if np.any(t_eval < min(t0, tf)) or np.any(t_eval > max(t0, tf)):
+            raise ValueError("Values in `t_eval` are not within `t_span`.")
+
+        d = np.diff(t_eval)
+        if tf > t0 and np.any(d <= 0) or tf < t0 and np.any(d >= 0):
+            raise ValueError("Values in `t_eval` are not properly sorted.")
+
+        if tf > t0:
+            t_eval_i = 0
+        else:
+            # Make order of t_eval decreasing to use np.searchsorted.
+            t_eval = t_eval[::-1]
+            # This will be an upper bound for slices.
+            t_eval_i = t_eval.shape[0]
+
+    if method in METHODS:
+        method = METHODS[method]
+
+    solver = method(fun, t0, y0, tf, vectorized=vectorized, **options)
+
+    if t_eval is None:
+        ts = [t0]
+        ys = [y0]
+    elif t_eval is not None and dense_output:
+        ts = []
+        ti = [t0]
+        ys = []
+    else:
+        ts = []
+        ys = []
+
+    interpolants = []
+
+    if events is not None:
+        events, max_events, event_dir = prepare_events(events)
+        event_count = np.zeros(len(events))
+        if args is not None:
+            # Wrap user functions in lambdas to hide the additional parameters.
+            # The original event function is passed as a keyword argument to the
+            # lambda to keep the original function in scope (i.e., avoid the
+            # late binding closure "gotcha").
+            events = [lambda t, x, event=event: event(t, x, *args)
+                      for event in events]
+        g = [event(t0, y0) for event in events]
+        t_events = [[] for _ in range(len(events))]
+        y_events = [[] for _ in range(len(events))]
+    else:
+        t_events = None
+        y_events = None
+
+    status = None
+    while status is None:
+        message = solver.step()
+
+        if solver.status == 'finished':
+            status = 0
+        elif solver.status == 'failed':
+            status = -1
+            break
+
+        t_old = solver.t_old
+        t = solver.t
+        y = solver.y
+
+        if dense_output:
+            sol = solver.dense_output()
+            interpolants.append(sol)
+        else:
+            sol = None
+
+        if events is not None:
+            g_new = [event(t, y) for event in events]
+            active_events = find_active_events(g, g_new, event_dir)
+            if active_events.size > 0:
+                if sol is None:
+                    sol = solver.dense_output()
+
+                event_count[active_events] += 1
+                root_indices, roots, terminate = handle_events(
+                    sol, events, active_events, event_count, max_events,
+                    t_old, t)
+
+                for e, te in zip(root_indices, roots):
+                    t_events[e].append(te)
+                    y_events[e].append(sol(te))
+
+                if terminate:
+                    status = 1
+                    t = roots[-1]
+                    y = sol(t)
+
+            g = g_new
+
+        if t_eval is None:
+            ts.append(t)
+            ys.append(y)
+        else:
+            # The value in t_eval equal to t will be included.
+            if solver.direction > 0:
+                t_eval_i_new = np.searchsorted(t_eval, t, side='right')
+                t_eval_step = t_eval[t_eval_i:t_eval_i_new]
+            else:
+                t_eval_i_new = np.searchsorted(t_eval, t, side='left')
+                # It has to be done with two slice operations, because
+                # you can't slice to 0th element inclusive using backward
+                # slicing.
+                t_eval_step = t_eval[t_eval_i_new:t_eval_i][::-1]
+
+            if t_eval_step.size > 0:
+                if sol is None:
+                    sol = solver.dense_output()
+                ts.append(t_eval_step)
+                ys.append(sol(t_eval_step))
+                t_eval_i = t_eval_i_new
+
+        if t_eval is not None and dense_output:
+            ti.append(t)
+
+    message = MESSAGES.get(status, message)
+
+    if t_events is not None:
+        t_events = [np.asarray(te) for te in t_events]
+        y_events = [np.asarray(ye) for ye in y_events]
+
+    if t_eval is None:
+        ts = np.array(ts)
+        ys = np.vstack(ys).T
+    elif ts:
+        ts = np.hstack(ts)
+        ys = np.hstack(ys)
+
+    if dense_output:
+        if t_eval is None:
+            sol = OdeSolution(
+                ts, interpolants, alt_segment=True if method in [BDF, LSODA] else False
+            )
+        else:
+            sol = OdeSolution(
+                ti, interpolants, alt_segment=True if method in [BDF, LSODA] else False
+            )
+    else:
+        sol = None
+
+    return OdeResult(t=ts, y=ys, sol=sol, t_events=t_events, y_events=y_events,
+                     nfev=solver.nfev, njev=solver.njev, nlu=solver.nlu,
+                     status=status, message=message, success=status >= 0)

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/lsoda.py

@@ -0,0 +1,224 @@
+import numpy as np
+from scipy.integrate import ode
+from .common import validate_tol, validate_first_step, warn_extraneous
+from .base import OdeSolver, DenseOutput
+
+
+class LSODA(OdeSolver):
+    """Adams/BDF method with automatic stiffness detection and switching.
+
+    This is a wrapper to the Fortran solver from ODEPACK [1]_. It switches
+    automatically between the nonstiff Adams method and the stiff BDF method.
+    The method was originally detailed in [2]_.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system: the time derivative of the state ``y``
+        at time ``t``. The calling signature is ``fun(t, y)``, where ``t`` is a
+        scalar and ``y`` is an ndarray with ``len(y) = len(y0)``. ``fun`` must
+        return an array of the same shape as ``y``. See `vectorized` for more
+        information.
+    t0 : float
+        Initial time.
+    y0 : array_like, shape (n,)
+        Initial state.
+    t_bound : float
+        Boundary time - the integration won't continue beyond it. It also
+        determines the direction of the integration.
+    first_step : float or None, optional
+        Initial step size. Default is ``None`` which means that the algorithm
+        should choose.
+    min_step : float, optional
+        Minimum allowed step size. Default is 0.0, i.e., the step size is not
+        bounded and determined solely by the solver.
+    max_step : float, optional
+        Maximum allowed step size. Default is np.inf, i.e., the step size is not
+        bounded and determined solely by the solver.
+    rtol, atol : float and array_like, optional
+        Relative and absolute tolerances. The solver keeps the local error
+        estimates less than ``atol + rtol * abs(y)``. Here `rtol` controls a
+        relative accuracy (number of correct digits), while `atol` controls
+        absolute accuracy (number of correct decimal places). To achieve the
+        desired `rtol`, set `atol` to be smaller than the smallest value that
+        can be expected from ``rtol * abs(y)`` so that `rtol` dominates the
+        allowable error. If `atol` is larger than ``rtol * abs(y)`` the
+        number of correct digits is not guaranteed. Conversely, to achieve the
+        desired `atol` set `rtol` such that ``rtol * abs(y)`` is always smaller
+        than `atol`. If components of y have different scales, it might be
+        beneficial to set different `atol` values for different components by
+        passing array_like with shape (n,) for `atol`. Default values are
+        1e-3 for `rtol` and 1e-6 for `atol`.
+    jac : None or callable, optional
+        Jacobian matrix of the right-hand side of the system with respect to
+        ``y``. The Jacobian matrix has shape (n, n) and its element (i, j) is
+        equal to ``d f_i / d y_j``. The function will be called as
+        ``jac(t, y)``. If None (default), the Jacobian will be
+        approximated by finite differences. It is generally recommended to
+        provide the Jacobian rather than relying on a finite-difference
+        approximation.
+    lband, uband : int or None
+        Parameters defining the bandwidth of the Jacobian,
+        i.e., ``jac[i, j] != 0 only for i - lband <= j <= i + uband``. Setting
+        these requires your jac routine to return the Jacobian in the packed format:
+        the returned array must have ``n`` columns and ``uband + lband + 1``
+        rows in which Jacobian diagonals are written. Specifically
+        ``jac_packed[uband + i - j , j] = jac[i, j]``. The same format is used
+        in `scipy.linalg.solve_banded` (check for an illustration).
+        These parameters can be also used with ``jac=None`` to reduce the
+        number of Jacobian elements estimated by finite differences.
+    vectorized : bool, optional
+        Whether `fun` may be called in a vectorized fashion. False (default)
+        is recommended for this solver.
+
+        If ``vectorized`` is False, `fun` will always be called with ``y`` of
+        shape ``(n,)``, where ``n = len(y0)``.
+
+        If ``vectorized`` is True, `fun` may be called with ``y`` of shape
+        ``(n, k)``, where ``k`` is an integer. In this case, `fun` must behave
+        such that ``fun(t, y)[:, i] == fun(t, y[:, i])`` (i.e. each column of
+        the returned array is the time derivative of the state corresponding
+        with a column of ``y``).
+
+        Setting ``vectorized=True`` allows for faster finite difference
+        approximation of the Jacobian by methods 'Radau' and 'BDF', but
+        will result in slower execution for this solver.
+
+    Attributes
+    ----------
+    n : int
+        Number of equations.
+    status : string
+        Current status of the solver: 'running', 'finished' or 'failed'.
+    t_bound : float
+        Boundary time.
+    direction : float
+        Integration direction: +1 or -1.
+    t : float
+        Current time.
+    y : ndarray
+        Current state.
+    t_old : float
+        Previous time. None if no steps were made yet.
+    nfev : int
+        Number of evaluations of the right-hand side.
+    njev : int
+        Number of evaluations of the Jacobian.
+
+    References
+    ----------
+    .. [1] A. C. Hindmarsh, "ODEPACK, A Systematized Collection of ODE
+           Solvers," IMACS Transactions on Scientific Computation, Vol 1.,
+           pp. 55-64, 1983.
+    .. [2] L. Petzold, "Automatic selection of methods for solving stiff and
+           nonstiff systems of ordinary differential equations", SIAM Journal
+           on Scientific and Statistical Computing, Vol. 4, No. 1, pp. 136-148,
+           1983.
+    """
+    def __init__(self, fun, t0, y0, t_bound, first_step=None, min_step=0.0,
+                 max_step=np.inf, rtol=1e-3, atol=1e-6, jac=None, lband=None,
+                 uband=None, vectorized=False, **extraneous):
+        warn_extraneous(extraneous)
+        super().__init__(fun, t0, y0, t_bound, vectorized)
+
+        if first_step is None:
+            first_step = 0  # LSODA value for automatic selection.
+        else:
+            first_step = validate_first_step(first_step, t0, t_bound)
+
+        first_step *= self.direction
+
+        if max_step == np.inf:
+            max_step = 0  # LSODA value for infinity.
+        elif max_step <= 0:
+            raise ValueError("`max_step` must be positive.")
+
+        if min_step < 0:
+            raise ValueError("`min_step` must be nonnegative.")
+
+        rtol, atol = validate_tol(rtol, atol, self.n)
+
+        solver = ode(self.fun, jac)
+        solver.set_integrator('lsoda', rtol=rtol, atol=atol, max_step=max_step,
+                              min_step=min_step, first_step=first_step,
+                              lband=lband, uband=uband)
+        solver.set_initial_value(y0, t0)
+
+        # Inject t_bound into rwork array as needed for itask=5.
+        solver._integrator.rwork[0] = self.t_bound
+        solver._integrator.call_args[4] = solver._integrator.rwork
+
+        self._lsoda_solver = solver
+
+    def _step_impl(self):
+        solver = self._lsoda_solver
+        integrator = solver._integrator
+
+        # From lsoda.step and lsoda.integrate itask=5 means take a single
+        # step and do not go past t_bound.
+        itask = integrator.call_args[2]
+        integrator.call_args[2] = 5
+        solver._y, solver.t = integrator.run(
+            solver.f, solver.jac or (lambda: None), solver._y, solver.t,
+            self.t_bound, solver.f_params, solver.jac_params)
+        integrator.call_args[2] = itask
+
+        if solver.successful():
+            self.t = solver.t
+            self.y = solver._y
+            # From LSODA Fortran source njev is equal to nlu.
+            self.njev = integrator.iwork[12]
+            self.nlu = integrator.iwork[12]
+            return True, None
+        else:
+            return False, 'Unexpected istate in LSODA.'
+
+    def _dense_output_impl(self):
+        iwork = self._lsoda_solver._integrator.iwork
+        rwork = self._lsoda_solver._integrator.rwork
+
+        # We want to produce the Nordsieck history array, yh, up to the order
+        # used in the last successful iteration. The step size is unimportant
+        # because it will be scaled out in LsodaDenseOutput. Some additional
+        # work may be required because ODEPACK's LSODA implementation produces
+        # the Nordsieck history in the state needed for the next iteration.
+
+        # iwork[13] contains order from last successful iteration, while
+        # iwork[14] contains order to be attempted next.
+        order = iwork[13]
+
+        # rwork[11] contains the step size to be attempted next, while
+        # rwork[10] contains step size from last successful iteration.
+        h = rwork[11]
+
+        # rwork[20:20 + (iwork[14] + 1) * self.n] contains entries of the
+        # Nordsieck array in state needed for next iteration. We want
+        # the entries up to order for the last successful step so use the 
+        # following.
+        yh = np.reshape(rwork[20:20 + (order + 1) * self.n],
+                        (self.n, order + 1), order='F').copy()
+        if iwork[14] < order:
+            # If the order is set to decrease then the final column of yh
+            # has not been updated within ODEPACK's LSODA
+            # implementation because this column will not be used in the
+            # next iteration. We must rescale this column to make the
+            # associated step size consistent with the other columns.
+            yh[:, -1] *= (h / rwork[10]) ** order
+
+        return LsodaDenseOutput(self.t_old, self.t, h, order, yh)
+
+
+class LsodaDenseOutput(DenseOutput):
+    def __init__(self, t_old, t, h, order, yh):
+        super().__init__(t_old, t)
+        self.h = h
+        self.yh = yh
+        self.p = np.arange(order + 1)
+
+    def _call_impl(self, t):
+        if t.ndim == 0:
+            x = ((t - self.t) / self.h) ** self.p
+        else:
+            x = ((t - self.t) / self.h) ** self.p[:, None]
+
+        return np.dot(self.yh, x)

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/radau.py

@@ -0,0 +1,574 @@
+import numpy as np
+from scipy.linalg import lu_factor, lu_solve
+from scipy.sparse import csc_matrix, issparse, eye
+from scipy.sparse.linalg import splu
+from scipy.optimize._numdiff import group_columns
+from .common import (validate_max_step, validate_tol, select_initial_step,
+                     norm, num_jac, EPS, warn_extraneous,
+                     validate_first_step)
+from .base import OdeSolver, DenseOutput
+
+S6 = 6 ** 0.5
+
+# Butcher tableau. A is not used directly, see below.
+C = np.array([(4 - S6) / 10, (4 + S6) / 10, 1])
+E = np.array([-13 - 7 * S6, -13 + 7 * S6, -1]) / 3
+
+# Eigendecomposition of A is done: A = T L T**-1. There is 1 real eigenvalue
+# and a complex conjugate pair. They are written below.
+MU_REAL = 3 + 3 ** (2 / 3) - 3 ** (1 / 3)
+MU_COMPLEX = (3 + 0.5 * (3 ** (1 / 3) - 3 ** (2 / 3))
+              - 0.5j * (3 ** (5 / 6) + 3 ** (7 / 6)))
+
+# These are transformation matrices.
+T = np.array([
+    [0.09443876248897524, -0.14125529502095421, 0.03002919410514742],
+    [0.25021312296533332, 0.20412935229379994, -0.38294211275726192],
+    [1, 1, 0]])
+TI = np.array([
+    [4.17871859155190428, 0.32768282076106237, 0.52337644549944951],
+    [-4.17871859155190428, -0.32768282076106237, 0.47662355450055044],
+    [0.50287263494578682, -2.57192694985560522, 0.59603920482822492]])
+# These linear combinations are used in the algorithm.
+TI_REAL = TI[0]
+TI_COMPLEX = TI[1] + 1j * TI[2]
+
+# Interpolator coefficients.
+P = np.array([
+    [13/3 + 7*S6/3, -23/3 - 22*S6/3, 10/3 + 5 * S6],
+    [13/3 - 7*S6/3, -23/3 + 22*S6/3, 10/3 - 5 * S6],
+    [1/3, -8/3, 10/3]])
+
+
+NEWTON_MAXITER = 6  # Maximum number of Newton iterations.
+MIN_FACTOR = 0.2  # Minimum allowed decrease in a step size.
+MAX_FACTOR = 10  # Maximum allowed increase in a step size.
+
+
+def solve_collocation_system(fun, t, y, h, Z0, scale, tol,
+                             LU_real, LU_complex, solve_lu):
+    """Solve the collocation system.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system.
+    t : float
+        Current time.
+    y : ndarray, shape (n,)
+        Current state.
+    h : float
+        Step to try.
+    Z0 : ndarray, shape (3, n)
+        Initial guess for the solution. It determines new values of `y` at
+        ``t + h * C`` as ``y + Z0``, where ``C`` is the Radau method constants.
+    scale : ndarray, shape (n)
+        Problem tolerance scale, i.e. ``rtol * abs(y) + atol``.
+    tol : float
+        Tolerance to which solve the system. This value is compared with
+        the normalized by `scale` error.
+    LU_real, LU_complex
+        LU decompositions of the system Jacobians.
+    solve_lu : callable
+        Callable which solves a linear system given a LU decomposition. The
+        signature is ``solve_lu(LU, b)``.
+
+    Returns
+    -------
+    converged : bool
+        Whether iterations converged.
+    n_iter : int
+        Number of completed iterations.
+    Z : ndarray, shape (3, n)
+        Found solution.
+    rate : float
+        The rate of convergence.
+    """
+    n = y.shape[0]
+    M_real = MU_REAL / h
+    M_complex = MU_COMPLEX / h
+
+    W = TI.dot(Z0)
+    Z = Z0
+
+    F = np.empty((3, n))
+    ch = h * C
+
+    dW_norm_old = None
+    dW = np.empty_like(W)
+    converged = False
+    rate = None
+    for k in range(NEWTON_MAXITER):
+        for i in range(3):
+            F[i] = fun(t + ch[i], y + Z[i])
+
+        if not np.all(np.isfinite(F)):
+            break
+
+        f_real = F.T.dot(TI_REAL) - M_real * W[0]
+        f_complex = F.T.dot(TI_COMPLEX) - M_complex * (W[1] + 1j * W[2])
+
+        dW_real = solve_lu(LU_real, f_real)
+        dW_complex = solve_lu(LU_complex, f_complex)
+
+        dW[0] = dW_real
+        dW[1] = dW_complex.real
+        dW[2] = dW_complex.imag
+
+        dW_norm = norm(dW / scale)
+        if dW_norm_old is not None:
+            rate = dW_norm / dW_norm_old
+
+        if (rate is not None and (rate >= 1 or
+                rate ** (NEWTON_MAXITER - k) / (1 - rate) * dW_norm > tol)):
+            break
+
+        W += dW
+        Z = T.dot(W)
+
+        if (dW_norm == 0 or
+                rate is not None and rate / (1 - rate) * dW_norm < tol):
+            converged = True
+            break
+
+        dW_norm_old = dW_norm
+
+    return converged, k + 1, Z, rate
+
+
+def predict_factor(h_abs, h_abs_old, error_norm, error_norm_old):
+    """Predict by which factor to increase/decrease the step size.
+
+    The algorithm is described in [1]_.
+
+    Parameters
+    ----------
+    h_abs, h_abs_old : float
+        Current and previous values of the step size, `h_abs_old` can be None
+        (see Notes).
+    error_norm, error_norm_old : float
+        Current and previous values of the error norm, `error_norm_old` can
+        be None (see Notes).
+
+    Returns
+    -------
+    factor : float
+        Predicted factor.
+
+    Notes
+    -----
+    If `h_abs_old` and `error_norm_old` are both not None then a two-step
+    algorithm is used, otherwise a one-step algorithm is used.
+
+    References
+    ----------
+    .. [1] E. Hairer, S. P. Norsett G. Wanner, "Solving Ordinary Differential
+           Equations II: Stiff and Differential-Algebraic Problems", Sec. IV.8.
+    """
+    if error_norm_old is None or h_abs_old is None or error_norm == 0:
+        multiplier = 1
+    else:
+        multiplier = h_abs / h_abs_old * (error_norm_old / error_norm) ** 0.25
+
+    with np.errstate(divide='ignore'):
+        factor = min(1, multiplier) * error_norm ** -0.25
+
+    return factor
+
+
+class Radau(OdeSolver):
+    """Implicit Runge-Kutta method of Radau IIA family of order 5.
+
+    The implementation follows [1]_. The error is controlled with a
+    third-order accurate embedded formula. A cubic polynomial which satisfies
+    the collocation conditions is used for the dense output.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system: the time derivative of the state ``y``
+        at time ``t``. The calling signature is ``fun(t, y)``, where ``t`` is a
+        scalar and ``y`` is an ndarray with ``len(y) = len(y0)``. ``fun`` must
+        return an array of the same shape as ``y``. See `vectorized` for more
+        information.
+    t0 : float
+        Initial time.
+    y0 : array_like, shape (n,)
+        Initial state.
+    t_bound : float
+        Boundary time - the integration won't continue beyond it. It also
+        determines the direction of the integration.
+    first_step : float or None, optional
+        Initial step size. Default is ``None`` which means that the algorithm
+        should choose.
+    max_step : float, optional
+        Maximum allowed step size. Default is np.inf, i.e., the step size is not
+        bounded and determined solely by the solver.
+    rtol, atol : float and array_like, optional
+        Relative and absolute tolerances. The solver keeps the local error
+        estimates less than ``atol + rtol * abs(y)``. HHere `rtol` controls a
+        relative accuracy (number of correct digits), while `atol` controls
+        absolute accuracy (number of correct decimal places). To achieve the
+        desired `rtol`, set `atol` to be smaller than the smallest value that
+        can be expected from ``rtol * abs(y)`` so that `rtol` dominates the
+        allowable error. If `atol` is larger than ``rtol * abs(y)`` the
+        number of correct digits is not guaranteed. Conversely, to achieve the
+        desired `atol` set `rtol` such that ``rtol * abs(y)`` is always smaller
+        than `atol`. If components of y have different scales, it might be
+        beneficial to set different `atol` values for different components by
+        passing array_like with shape (n,) for `atol`. Default values are
+        1e-3 for `rtol` and 1e-6 for `atol`.
+    jac : {None, array_like, sparse_matrix, callable}, optional
+        Jacobian matrix of the right-hand side of the system with respect to
+        y, required by this method. The Jacobian matrix has shape (n, n) and
+        its element (i, j) is equal to ``d f_i / d y_j``.
+        There are three ways to define the Jacobian:
+
+            * If array_like or sparse_matrix, the Jacobian is assumed to
+              be constant.
+            * If callable, the Jacobian is assumed to depend on both
+              t and y; it will be called as ``jac(t, y)`` as necessary.
+              For the 'Radau' and 'BDF' methods, the return value might be a
+              sparse matrix.
+            * If None (default), the Jacobian will be approximated by
+              finite differences.
+
+        It is generally recommended to provide the Jacobian rather than
+        relying on a finite-difference approximation.
+    jac_sparsity : {None, array_like, sparse matrix}, optional
+        Defines a sparsity structure of the Jacobian matrix for a
+        finite-difference approximation. Its shape must be (n, n). This argument
+        is ignored if `jac` is not `None`. If the Jacobian has only few non-zero
+        elements in *each* row, providing the sparsity structure will greatly
+        speed up the computations [2]_. A zero entry means that a corresponding
+        element in the Jacobian is always zero. If None (default), the Jacobian
+        is assumed to be dense.
+    vectorized : bool, optional
+        Whether `fun` can be called in a vectorized fashion. Default is False.
+
+        If ``vectorized`` is False, `fun` will always be called with ``y`` of
+        shape ``(n,)``, where ``n = len(y0)``.
+
+        If ``vectorized`` is True, `fun` may be called with ``y`` of shape
+        ``(n, k)``, where ``k`` is an integer. In this case, `fun` must behave
+        such that ``fun(t, y)[:, i] == fun(t, y[:, i])`` (i.e. each column of
+        the returned array is the time derivative of the state corresponding
+        with a column of ``y``).
+
+        Setting ``vectorized=True`` allows for faster finite difference
+        approximation of the Jacobian by this method, but may result in slower
+        execution overall in some circumstances (e.g. small ``len(y0)``).
+
+    Attributes
+    ----------
+    n : int
+        Number of equations.
+    status : string
+        Current status of the solver: 'running', 'finished' or 'failed'.
+    t_bound : float
+        Boundary time.
+    direction : float
+        Integration direction: +1 or -1.
+    t : float
+        Current time.
+    y : ndarray
+        Current state.
+    t_old : float
+        Previous time. None if no steps were made yet.
+    step_size : float
+        Size of the last successful step. None if no steps were made yet.
+    nfev : int
+        Number of evaluations of the right-hand side.
+    njev : int
+        Number of evaluations of the Jacobian.
+    nlu : int
+        Number of LU decompositions.
+
+    References
+    ----------
+    .. [1] E. Hairer, G. Wanner, "Solving Ordinary Differential Equations II:
+           Stiff and Differential-Algebraic Problems", Sec. IV.8.
+    .. [2] A. Curtis, M. J. D. Powell, and J. Reid, "On the estimation of
+           sparse Jacobian matrices", Journal of the Institute of Mathematics
+           and its Applications, 13, pp. 117-120, 1974.
+    """
+    def __init__(self, fun, t0, y0, t_bound, max_step=np.inf,
+                 rtol=1e-3, atol=1e-6, jac=None, jac_sparsity=None,
+                 vectorized=False, first_step=None, **extraneous):
+        warn_extraneous(extraneous)
+        super().__init__(fun, t0, y0, t_bound, vectorized)
+        self.y_old = None
+        self.max_step = validate_max_step(max_step)
+        self.rtol, self.atol = validate_tol(rtol, atol, self.n)
+        self.f = self.fun(self.t, self.y)
+        # Select initial step assuming the same order which is used to control
+        # the error.
+        if first_step is None:
+            self.h_abs = select_initial_step(
+                self.fun, self.t, self.y, self.f, self.direction,
+                3, self.rtol, self.atol)
+        else:
+            self.h_abs = validate_first_step(first_step, t0, t_bound)
+        self.h_abs_old = None
+        self.error_norm_old = None
+
+        self.newton_tol = max(10 * EPS / rtol, min(0.03, rtol ** 0.5))
+        self.sol = None
+
+        self.jac_factor = None
+        self.jac, self.J = self._validate_jac(jac, jac_sparsity)
+        if issparse(self.J):
+            def lu(A):
+                self.nlu += 1
+                return splu(A)
+
+            def solve_lu(LU, b):
+                return LU.solve(b)
+
+            I = eye(self.n, format='csc')
+        else:
+            def lu(A):
+                self.nlu += 1
+                return lu_factor(A, overwrite_a=True)
+
+            def solve_lu(LU, b):
+                return lu_solve(LU, b, overwrite_b=True)
+
+            I = np.identity(self.n)
+
+        self.lu = lu
+        self.solve_lu = solve_lu
+        self.I = I
+
+        self.current_jac = True
+        self.LU_real = None
+        self.LU_complex = None
+        self.Z = None
+
+    def _validate_jac(self, jac, sparsity):
+        t0 = self.t
+        y0 = self.y
+
+        if jac is None:
+            if sparsity is not None:
+                if issparse(sparsity):
+                    sparsity = csc_matrix(sparsity)
+                groups = group_columns(sparsity)
+                sparsity = (sparsity, groups)
+
+            def jac_wrapped(t, y, f):
+                self.njev += 1
+                J, self.jac_factor = num_jac(self.fun_vectorized, t, y, f,
+                                             self.atol, self.jac_factor,
+                                             sparsity)
+                return J
+            J = jac_wrapped(t0, y0, self.f)
+        elif callable(jac):
+            J = jac(t0, y0)
+            self.njev = 1
+            if issparse(J):
+                J = csc_matrix(J)
+
+                def jac_wrapped(t, y, _=None):
+                    self.njev += 1
+                    return csc_matrix(jac(t, y), dtype=float)
+
+            else:
+                J = np.asarray(J, dtype=float)
+
+                def jac_wrapped(t, y, _=None):
+                    self.njev += 1
+                    return np.asarray(jac(t, y), dtype=float)
+
+            if J.shape != (self.n, self.n):
+                raise ValueError("`jac` is expected to have shape {}, but "
+                                 "actually has {}."
+                                 .format((self.n, self.n), J.shape))
+        else:
+            if issparse(jac):
+                J = csc_matrix(jac)
+            else:
+                J = np.asarray(jac, dtype=float)
+
+            if J.shape != (self.n, self.n):
+                raise ValueError("`jac` is expected to have shape {}, but "
+                                 "actually has {}."
+                                 .format((self.n, self.n), J.shape))
+            jac_wrapped = None
+
+        return jac_wrapped, J
+
+    def _step_impl(self):
+        t = self.t
+        y = self.y
+        f = self.f
+
+        max_step = self.max_step
+        atol = self.atol
+        rtol = self.rtol
+
+        min_step = 10 * np.abs(np.nextafter(t, self.direction * np.inf) - t)
+        if self.h_abs > max_step:
+            h_abs = max_step
+            h_abs_old = None
+            error_norm_old = None
+        elif self.h_abs < min_step:
+            h_abs = min_step
+            h_abs_old = None
+            error_norm_old = None
+        else:
+            h_abs = self.h_abs
+            h_abs_old = self.h_abs_old
+            error_norm_old = self.error_norm_old
+
+        J = self.J
+        LU_real = self.LU_real
+        LU_complex = self.LU_complex
+
+        current_jac = self.current_jac
+        jac = self.jac
+
+        rejected = False
+        step_accepted = False
+        message = None
+        while not step_accepted:
+            if h_abs < min_step:
+                return False, self.TOO_SMALL_STEP
+
+            h = h_abs * self.direction
+            t_new = t + h
+
+            if self.direction * (t_new - self.t_bound) > 0:
+                t_new = self.t_bound
+
+            h = t_new - t
+            h_abs = np.abs(h)
+
+            if self.sol is None:
+                Z0 = np.zeros((3, y.shape[0]))
+            else:
+                Z0 = self.sol(t + h * C).T - y
+
+            scale = atol + np.abs(y) * rtol
+
+            converged = False
+            while not converged:
+                if LU_real is None or LU_complex is None:
+                    LU_real = self.lu(MU_REAL / h * self.I - J)
+                    LU_complex = self.lu(MU_COMPLEX / h * self.I - J)
+
+                converged, n_iter, Z, rate = solve_collocation_system(
+                    self.fun, t, y, h, Z0, scale, self.newton_tol,
+                    LU_real, LU_complex, self.solve_lu)
+
+                if not converged:
+                    if current_jac:
+                        break
+
+                    J = self.jac(t, y, f)
+                    current_jac = True
+                    LU_real = None
+                    LU_complex = None
+
+            if not converged:
+                h_abs *= 0.5
+                LU_real = None
+                LU_complex = None
+                continue
+
+            y_new = y + Z[-1]
+            ZE = Z.T.dot(E) / h
+            error = self.solve_lu(LU_real, f + ZE)
+            scale = atol + np.maximum(np.abs(y), np.abs(y_new)) * rtol
+            error_norm = norm(error / scale)
+            safety = 0.9 * (2 * NEWTON_MAXITER + 1) / (2 * NEWTON_MAXITER
+                                                       + n_iter)
+
+            if rejected and error_norm > 1:
+                error = self.solve_lu(LU_real, self.fun(t, y + error) + ZE)
+                error_norm = norm(error / scale)
+
+            if error_norm > 1:
+                factor = predict_factor(h_abs, h_abs_old,
+                                        error_norm, error_norm_old)
+                h_abs *= max(MIN_FACTOR, safety * factor)
+
+                LU_real = None
+                LU_complex = None
+                rejected = True
+            else:
+                step_accepted = True
+
+        recompute_jac = jac is not None and n_iter > 2 and rate > 1e-3
+
+        factor = predict_factor(h_abs, h_abs_old, error_norm, error_norm_old)
+        factor = min(MAX_FACTOR, safety * factor)
+
+        if not recompute_jac and factor < 1.2:
+            factor = 1
+        else:
+            LU_real = None
+            LU_complex = None
+
+        f_new = self.fun(t_new, y_new)
+        if recompute_jac:
+            J = jac(t_new, y_new, f_new)
+            current_jac = True
+        elif jac is not None:
+            current_jac = False
+
+        self.h_abs_old = self.h_abs
+        self.error_norm_old = error_norm
+
+        self.h_abs = h_abs * factor
+
+        self.y_old = y
+
+        self.t = t_new
+        self.y = y_new
+        self.f = f_new
+
+        self.Z = Z
+
+        self.LU_real = LU_real
+        self.LU_complex = LU_complex
+        self.current_jac = current_jac
+        self.J = J
+
+        self.t_old = t
+        self.sol = self._compute_dense_output()
+
+        return step_accepted, message
+
+    def _compute_dense_output(self):
+        Q = np.dot(self.Z.T, P)
+        return RadauDenseOutput(self.t_old, self.t, self.y_old, Q)
+
+    def _dense_output_impl(self):
+        return self.sol
+
+
+class RadauDenseOutput(DenseOutput):
+    def __init__(self, t_old, t, y_old, Q):
+        super().__init__(t_old, t)
+        self.h = t - t_old
+        self.Q = Q
+        self.order = Q.shape[1] - 1
+        self.y_old = y_old
+
+    def _call_impl(self, t):
+        x = (t - self.t_old) / self.h
+        if t.ndim == 0:
+            p = np.tile(x, self.order + 1)
+            p = np.cumprod(p)
+        else:
+            p = np.tile(x, (self.order + 1, 1))
+            p = np.cumprod(p, axis=0)
+        # Here we don't multiply by h, not a mistake.
+        y = np.dot(self.Q, p)
+        if y.ndim == 2:
+            y += self.y_old[:, None]
+        else:
+            y += self.y_old
+
+        return y

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/rk.py

@@ -0,0 +1,601 @@
+import numpy as np
+from .base import OdeSolver, DenseOutput
+from .common import (validate_max_step, validate_tol, select_initial_step,
+                     norm, warn_extraneous, validate_first_step)
+from . import dop853_coefficients
+
+# Multiply steps computed from asymptotic behaviour of errors by this.
+SAFETY = 0.9
+
+MIN_FACTOR = 0.2  # Minimum allowed decrease in a step size.
+MAX_FACTOR = 10  # Maximum allowed increase in a step size.
+
+
+def rk_step(fun, t, y, f, h, A, B, C, K):
+    """Perform a single Runge-Kutta step.
+
+    This function computes a prediction of an explicit Runge-Kutta method and
+    also estimates the error of a less accurate method.
+
+    Notation for Butcher tableau is as in [1]_.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system.
+    t : float
+        Current time.
+    y : ndarray, shape (n,)
+        Current state.
+    f : ndarray, shape (n,)
+        Current value of the derivative, i.e., ``fun(x, y)``.
+    h : float
+        Step to use.
+    A : ndarray, shape (n_stages, n_stages)
+        Coefficients for combining previous RK stages to compute the next
+        stage. For explicit methods the coefficients at and above the main
+        diagonal are zeros.
+    B : ndarray, shape (n_stages,)
+        Coefficients for combining RK stages for computing the final
+        prediction.
+    C : ndarray, shape (n_stages,)
+        Coefficients for incrementing time for consecutive RK stages.
+        The value for the first stage is always zero.
+    K : ndarray, shape (n_stages + 1, n)
+        Storage array for putting RK stages here. Stages are stored in rows.
+        The last row is a linear combination of the previous rows with
+        coefficients
+
+    Returns
+    -------
+    y_new : ndarray, shape (n,)
+        Solution at t + h computed with a higher accuracy.
+    f_new : ndarray, shape (n,)
+        Derivative ``fun(t + h, y_new)``.
+
+    References
+    ----------
+    .. [1] E. Hairer, S. P. Norsett G. Wanner, "Solving Ordinary Differential
+           Equations I: Nonstiff Problems", Sec. II.4.
+    """
+    K[0] = f
+    for s, (a, c) in enumerate(zip(A[1:], C[1:]), start=1):
+        dy = np.dot(K[:s].T, a[:s]) * h
+        K[s] = fun(t + c * h, y + dy)
+
+    y_new = y + h * np.dot(K[:-1].T, B)
+    f_new = fun(t + h, y_new)
+
+    K[-1] = f_new
+
+    return y_new, f_new
+
+
+class RungeKutta(OdeSolver):
+    """Base class for explicit Runge-Kutta methods."""
+    C: np.ndarray = NotImplemented
+    A: np.ndarray = NotImplemented
+    B: np.ndarray = NotImplemented
+    E: np.ndarray = NotImplemented
+    P: np.ndarray = NotImplemented
+    order: int = NotImplemented
+    error_estimator_order: int = NotImplemented
+    n_stages: int = NotImplemented
+
+    def __init__(self, fun, t0, y0, t_bound, max_step=np.inf,
+                 rtol=1e-3, atol=1e-6, vectorized=False,
+                 first_step=None, **extraneous):
+        warn_extraneous(extraneous)
+        super().__init__(fun, t0, y0, t_bound, vectorized,
+                         support_complex=True)
+        self.y_old = None
+        self.max_step = validate_max_step(max_step)
+        self.rtol, self.atol = validate_tol(rtol, atol, self.n)
+        self.f = self.fun(self.t, self.y)
+        if first_step is None:
+            self.h_abs = select_initial_step(
+                self.fun, self.t, self.y, self.f, self.direction,
+                self.error_estimator_order, self.rtol, self.atol)
+        else:
+            self.h_abs = validate_first_step(first_step, t0, t_bound)
+        self.K = np.empty((self.n_stages + 1, self.n), dtype=self.y.dtype)
+        self.error_exponent = -1 / (self.error_estimator_order + 1)
+        self.h_previous = None
+
+    def _estimate_error(self, K, h):
+        return np.dot(K.T, self.E) * h
+
+    def _estimate_error_norm(self, K, h, scale):
+        return norm(self._estimate_error(K, h) / scale)
+
+    def _step_impl(self):
+        t = self.t
+        y = self.y
+
+        max_step = self.max_step
+        rtol = self.rtol
+        atol = self.atol
+
+        min_step = 10 * np.abs(np.nextafter(t, self.direction * np.inf) - t)
+
+        if self.h_abs > max_step:
+            h_abs = max_step
+        elif self.h_abs < min_step:
+            h_abs = min_step
+        else:
+            h_abs = self.h_abs
+
+        step_accepted = False
+        step_rejected = False
+
+        while not step_accepted:
+            if h_abs < min_step:
+                return False, self.TOO_SMALL_STEP
+
+            h = h_abs * self.direction
+            t_new = t + h
+
+            if self.direction * (t_new - self.t_bound) > 0:
+                t_new = self.t_bound
+
+            h = t_new - t
+            h_abs = np.abs(h)
+
+            y_new, f_new = rk_step(self.fun, t, y, self.f, h, self.A,
+                                   self.B, self.C, self.K)
+            scale = atol + np.maximum(np.abs(y), np.abs(y_new)) * rtol
+            error_norm = self._estimate_error_norm(self.K, h, scale)
+
+            if error_norm < 1:
+                if error_norm == 0:
+                    factor = MAX_FACTOR
+                else:
+                    factor = min(MAX_FACTOR,
+                                 SAFETY * error_norm ** self.error_exponent)
+
+                if step_rejected:
+                    factor = min(1, factor)
+
+                h_abs *= factor
+
+                step_accepted = True
+            else:
+                h_abs *= max(MIN_FACTOR,
+                             SAFETY * error_norm ** self.error_exponent)
+                step_rejected = True
+
+        self.h_previous = h
+        self.y_old = y
+
+        self.t = t_new
+        self.y = y_new
+
+        self.h_abs = h_abs
+        self.f = f_new
+
+        return True, None
+
+    def _dense_output_impl(self):
+        Q = self.K.T.dot(self.P)
+        return RkDenseOutput(self.t_old, self.t, self.y_old, Q)
+
+
+class RK23(RungeKutta):
+    """Explicit Runge-Kutta method of order 3(2).
+
+    This uses the Bogacki-Shampine pair of formulas [1]_. The error is controlled
+    assuming accuracy of the second-order method, but steps are taken using the
+    third-order accurate formula (local extrapolation is done). A cubic Hermite
+    polynomial is used for the dense output.
+
+    Can be applied in the complex domain.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system: the time derivative of the state ``y``
+        at time ``t``. The calling signature is ``fun(t, y)``, where ``t`` is a
+        scalar and ``y`` is an ndarray with ``len(y) = len(y0)``. ``fun`` must
+        return an array of the same shape as ``y``. See `vectorized` for more
+        information.
+    t0 : float
+        Initial time.
+    y0 : array_like, shape (n,)
+        Initial state.
+    t_bound : float
+        Boundary time - the integration won't continue beyond it. It also
+        determines the direction of the integration.
+    first_step : float or None, optional
+        Initial step size. Default is ``None`` which means that the algorithm
+        should choose.
+    max_step : float, optional
+        Maximum allowed step size. Default is np.inf, i.e., the step size is not
+        bounded and determined solely by the solver.
+    rtol, atol : float and array_like, optional
+        Relative and absolute tolerances. The solver keeps the local error
+        estimates less than ``atol + rtol * abs(y)``. Here `rtol` controls a
+        relative accuracy (number of correct digits), while `atol` controls
+        absolute accuracy (number of correct decimal places). To achieve the
+        desired `rtol`, set `atol` to be smaller than the smallest value that
+        can be expected from ``rtol * abs(y)`` so that `rtol` dominates the
+        allowable error. If `atol` is larger than ``rtol * abs(y)`` the
+        number of correct digits is not guaranteed. Conversely, to achieve the
+        desired `atol` set `rtol` such that ``rtol * abs(y)`` is always smaller
+        than `atol`. If components of y have different scales, it might be
+        beneficial to set different `atol` values for different components by
+        passing array_like with shape (n,) for `atol`. Default values are
+        1e-3 for `rtol` and 1e-6 for `atol`.
+    vectorized : bool, optional
+        Whether `fun` may be called in a vectorized fashion. False (default)
+        is recommended for this solver.
+
+        If ``vectorized`` is False, `fun` will always be called with ``y`` of
+        shape ``(n,)``, where ``n = len(y0)``.
+
+        If ``vectorized`` is True, `fun` may be called with ``y`` of shape
+        ``(n, k)``, where ``k`` is an integer. In this case, `fun` must behave
+        such that ``fun(t, y)[:, i] == fun(t, y[:, i])`` (i.e. each column of
+        the returned array is the time derivative of the state corresponding
+        with a column of ``y``).
+
+        Setting ``vectorized=True`` allows for faster finite difference
+        approximation of the Jacobian by methods 'Radau' and 'BDF', but
+        will result in slower execution for this solver.
+
+    Attributes
+    ----------
+    n : int
+        Number of equations.
+    status : string
+        Current status of the solver: 'running', 'finished' or 'failed'.
+    t_bound : float
+        Boundary time.
+    direction : float
+        Integration direction: +1 or -1.
+    t : float
+        Current time.
+    y : ndarray
+        Current state.
+    t_old : float
+        Previous time. None if no steps were made yet.
+    step_size : float
+        Size of the last successful step. None if no steps were made yet.
+    nfev : int
+        Number evaluations of the system's right-hand side.
+    njev : int
+        Number of evaluations of the Jacobian.
+        Is always 0 for this solver as it does not use the Jacobian.
+    nlu : int
+        Number of LU decompositions. Is always 0 for this solver.
+
+    References
+    ----------
+    .. [1] P. Bogacki, L.F. Shampine, "A 3(2) Pair of Runge-Kutta Formulas",
+           Appl. Math. Lett. Vol. 2, No. 4. pp. 321-325, 1989.
+    """
+    order = 3
+    error_estimator_order = 2
+    n_stages = 3
+    C = np.array([0, 1/2, 3/4])
+    A = np.array([
+        [0, 0, 0],
+        [1/2, 0, 0],
+        [0, 3/4, 0]
+    ])
+    B = np.array([2/9, 1/3, 4/9])
+    E = np.array([5/72, -1/12, -1/9, 1/8])
+    P = np.array([[1, -4 / 3, 5 / 9],
+                  [0, 1, -2/3],
+                  [0, 4/3, -8/9],
+                  [0, -1, 1]])
+
+
+class RK45(RungeKutta):
+    """Explicit Runge-Kutta method of order 5(4).
+
+    This uses the Dormand-Prince pair of formulas [1]_. The error is controlled
+    assuming accuracy of the fourth-order method accuracy, but steps are taken
+    using the fifth-order accurate formula (local extrapolation is done).
+    A quartic interpolation polynomial is used for the dense output [2]_.
+
+    Can be applied in the complex domain.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system. The calling signature is ``fun(t, y)``.
+        Here ``t`` is a scalar, and there are two options for the ndarray ``y``:
+        It can either have shape (n,); then ``fun`` must return array_like with
+        shape (n,). Alternatively it can have shape (n, k); then ``fun``
+        must return an array_like with shape (n, k), i.e., each column
+        corresponds to a single column in ``y``. The choice between the two
+        options is determined by `vectorized` argument (see below).
+    t0 : float
+        Initial time.
+    y0 : array_like, shape (n,)
+        Initial state.
+    t_bound : float
+        Boundary time - the integration won't continue beyond it. It also
+        determines the direction of the integration.
+    first_step : float or None, optional
+        Initial step size. Default is ``None`` which means that the algorithm
+        should choose.
+    max_step : float, optional
+        Maximum allowed step size. Default is np.inf, i.e., the step size is not
+        bounded and determined solely by the solver.
+    rtol, atol : float and array_like, optional
+        Relative and absolute tolerances. The solver keeps the local error
+        estimates less than ``atol + rtol * abs(y)``. Here `rtol` controls a
+        relative accuracy (number of correct digits), while `atol` controls
+        absolute accuracy (number of correct decimal places). To achieve the
+        desired `rtol`, set `atol` to be smaller than the smallest value that
+        can be expected from ``rtol * abs(y)`` so that `rtol` dominates the
+        allowable error. If `atol` is larger than ``rtol * abs(y)`` the
+        number of correct digits is not guaranteed. Conversely, to achieve the
+        desired `atol` set `rtol` such that ``rtol * abs(y)`` is always smaller
+        than `atol`. If components of y have different scales, it might be
+        beneficial to set different `atol` values for different components by
+        passing array_like with shape (n,) for `atol`. Default values are
+        1e-3 for `rtol` and 1e-6 for `atol`.
+    vectorized : bool, optional
+        Whether `fun` is implemented in a vectorized fashion. Default is False.
+
+    Attributes
+    ----------
+    n : int
+        Number of equations.
+    status : string
+        Current status of the solver: 'running', 'finished' or 'failed'.
+    t_bound : float
+        Boundary time.
+    direction : float
+        Integration direction: +1 or -1.
+    t : float
+        Current time.
+    y : ndarray
+        Current state.
+    t_old : float
+        Previous time. None if no steps were made yet.
+    step_size : float
+        Size of the last successful step. None if no steps were made yet.
+    nfev : int
+        Number evaluations of the system's right-hand side.
+    njev : int
+        Number of evaluations of the Jacobian.
+        Is always 0 for this solver as it does not use the Jacobian.
+    nlu : int
+        Number of LU decompositions. Is always 0 for this solver.
+
+    References
+    ----------
+    .. [1] J. R. Dormand, P. J. Prince, "A family of embedded Runge-Kutta
+           formulae", Journal of Computational and Applied Mathematics, Vol. 6,
+           No. 1, pp. 19-26, 1980.
+    .. [2] L. W. Shampine, "Some Practical Runge-Kutta Formulas", Mathematics
+           of Computation,, Vol. 46, No. 173, pp. 135-150, 1986.
+    """
+    order = 5
+    error_estimator_order = 4
+    n_stages = 6
+    C = np.array([0, 1/5, 3/10, 4/5, 8/9, 1])
+    A = np.array([
+        [0, 0, 0, 0, 0],
+        [1/5, 0, 0, 0, 0],
+        [3/40, 9/40, 0, 0, 0],
+        [44/45, -56/15, 32/9, 0, 0],
+        [19372/6561, -25360/2187, 64448/6561, -212/729, 0],
+        [9017/3168, -355/33, 46732/5247, 49/176, -5103/18656]
+    ])
+    B = np.array([35/384, 0, 500/1113, 125/192, -2187/6784, 11/84])
+    E = np.array([-71/57600, 0, 71/16695, -71/1920, 17253/339200, -22/525,
+                  1/40])
+    # Corresponds to the optimum value of c_6 from [2]_.
+    P = np.array([
+        [1, -8048581381/2820520608, 8663915743/2820520608,
+         -12715105075/11282082432],
+        [0, 0, 0, 0],
+        [0, 131558114200/32700410799, -68118460800/10900136933,
+         87487479700/32700410799],
+        [0, -1754552775/470086768, 14199869525/1410260304,
+         -10690763975/1880347072],
+        [0, 127303824393/49829197408, -318862633887/49829197408,
+         701980252875 / 199316789632],
+        [0, -282668133/205662961, 2019193451/616988883, -1453857185/822651844],
+        [0, 40617522/29380423, -110615467/29380423, 69997945/29380423]])
+
+
+class DOP853(RungeKutta):
+    """Explicit Runge-Kutta method of order 8.
+
+    This is a Python implementation of "DOP853" algorithm originally written
+    in Fortran [1]_, [2]_. Note that this is not a literal translation, but
+    the algorithmic core and coefficients are the same.
+
+    Can be applied in the complex domain.
+
+    Parameters
+    ----------
+    fun : callable
+        Right-hand side of the system. The calling signature is ``fun(t, y)``.
+        Here, ``t`` is a scalar, and there are two options for the ndarray ``y``:
+        It can either have shape (n,); then ``fun`` must return array_like with
+        shape (n,). Alternatively it can have shape (n, k); then ``fun``
+        must return an array_like with shape (n, k), i.e. each column
+        corresponds to a single column in ``y``. The choice between the two
+        options is determined by `vectorized` argument (see below).
+    t0 : float
+        Initial time.
+    y0 : array_like, shape (n,)
+        Initial state.
+    t_bound : float
+        Boundary time - the integration won't continue beyond it. It also
+        determines the direction of the integration.
+    first_step : float or None, optional
+        Initial step size. Default is ``None`` which means that the algorithm
+        should choose.
+    max_step : float, optional
+        Maximum allowed step size. Default is np.inf, i.e. the step size is not
+        bounded and determined solely by the solver.
+    rtol, atol : float and array_like, optional
+        Relative and absolute tolerances. The solver keeps the local error
+        estimates less than ``atol + rtol * abs(y)``. Here `rtol` controls a
+        relative accuracy (number of correct digits), while `atol` controls
+        absolute accuracy (number of correct decimal places). To achieve the
+        desired `rtol`, set `atol` to be smaller than the smallest value that
+        can be expected from ``rtol * abs(y)`` so that `rtol` dominates the
+        allowable error. If `atol` is larger than ``rtol * abs(y)`` the
+        number of correct digits is not guaranteed. Conversely, to achieve the
+        desired `atol` set `rtol` such that ``rtol * abs(y)`` is always smaller
+        than `atol`. If components of y have different scales, it might be
+        beneficial to set different `atol` values for different components by
+        passing array_like with shape (n,) for `atol`. Default values are
+        1e-3 for `rtol` and 1e-6 for `atol`.
+    vectorized : bool, optional
+        Whether `fun` is implemented in a vectorized fashion. Default is False.
+
+    Attributes
+    ----------
+    n : int
+        Number of equations.
+    status : string
+        Current status of the solver: 'running', 'finished' or 'failed'.
+    t_bound : float
+        Boundary time.
+    direction : float
+        Integration direction: +1 or -1.
+    t : float
+        Current time.
+    y : ndarray
+        Current state.
+    t_old : float
+        Previous time. None if no steps were made yet.
+    step_size : float
+        Size of the last successful step. None if no steps were made yet.
+    nfev : int
+        Number evaluations of the system's right-hand side.
+    njev : int
+        Number of evaluations of the Jacobian. Is always 0 for this solver
+        as it does not use the Jacobian.
+    nlu : int
+        Number of LU decompositions. Is always 0 for this solver.
+
+    References
+    ----------
+    .. [1] E. Hairer, S. P. Norsett G. Wanner, "Solving Ordinary Differential
+           Equations I: Nonstiff Problems", Sec. II.
+    .. [2] `Page with original Fortran code of DOP853
+            <http://www.unige.ch/~hairer/software.html>`_.
+    """
+    n_stages = dop853_coefficients.N_STAGES
+    order = 8
+    error_estimator_order = 7
+    A = dop853_coefficients.A[:n_stages, :n_stages]
+    B = dop853_coefficients.B
+    C = dop853_coefficients.C[:n_stages]
+    E3 = dop853_coefficients.E3
+    E5 = dop853_coefficients.E5
+    D = dop853_coefficients.D
+
+    A_EXTRA = dop853_coefficients.A[n_stages + 1:]
+    C_EXTRA = dop853_coefficients.C[n_stages + 1:]
+
+    def __init__(self, fun, t0, y0, t_bound, max_step=np.inf,
+                 rtol=1e-3, atol=1e-6, vectorized=False,
+                 first_step=None, **extraneous):
+        super().__init__(fun, t0, y0, t_bound, max_step, rtol, atol,
+                         vectorized, first_step, **extraneous)
+        self.K_extended = np.empty((dop853_coefficients.N_STAGES_EXTENDED,
+                                    self.n), dtype=self.y.dtype)
+        self.K = self.K_extended[:self.n_stages + 1]
+
+    def _estimate_error(self, K, h):  # Left for testing purposes.
+        err5 = np.dot(K.T, self.E5)
+        err3 = np.dot(K.T, self.E3)
+        denom = np.hypot(np.abs(err5), 0.1 * np.abs(err3))
+        correction_factor = np.ones_like(err5)
+        mask = denom > 0
+        correction_factor[mask] = np.abs(err5[mask]) / denom[mask]
+        return h * err5 * correction_factor
+
+    def _estimate_error_norm(self, K, h, scale):
+        err5 = np.dot(K.T, self.E5) / scale
+        err3 = np.dot(K.T, self.E3) / scale
+        err5_norm_2 = np.linalg.norm(err5)**2
+        err3_norm_2 = np.linalg.norm(err3)**2
+        if err5_norm_2 == 0 and err3_norm_2 == 0:
+            return 0.0
+        denom = err5_norm_2 + 0.01 * err3_norm_2
+        return np.abs(h) * err5_norm_2 / np.sqrt(denom * len(scale))
+
+    def _dense_output_impl(self):
+        K = self.K_extended
+        h = self.h_previous
+        for s, (a, c) in enumerate(zip(self.A_EXTRA, self.C_EXTRA),
+                                   start=self.n_stages + 1):
+            dy = np.dot(K[:s].T, a[:s]) * h
+            K[s] = self.fun(self.t_old + c * h, self.y_old + dy)
+
+        F = np.empty((dop853_coefficients.INTERPOLATOR_POWER, self.n),
+                     dtype=self.y_old.dtype)
+
+        f_old = K[0]
+        delta_y = self.y - self.y_old
+
+        F[0] = delta_y
+        F[1] = h * f_old - delta_y
+        F[2] = 2 * delta_y - h * (self.f + f_old)
+        F[3:] = h * np.dot(self.D, K)
+
+        return Dop853DenseOutput(self.t_old, self.t, self.y_old, F)
+
+
+class RkDenseOutput(DenseOutput):
+    def __init__(self, t_old, t, y_old, Q):
+        super().__init__(t_old, t)
+        self.h = t - t_old
+        self.Q = Q
+        self.order = Q.shape[1] - 1
+        self.y_old = y_old
+
+    def _call_impl(self, t):
+        x = (t - self.t_old) / self.h
+        if t.ndim == 0:
+            p = np.tile(x, self.order + 1)
+            p = np.cumprod(p)
+        else:
+            p = np.tile(x, (self.order + 1, 1))
+            p = np.cumprod(p, axis=0)
+        y = self.h * np.dot(self.Q, p)
+        if y.ndim == 2:
+            y += self.y_old[:, None]
+        else:
+            y += self.y_old
+
+        return y
+
+
+class Dop853DenseOutput(DenseOutput):
+    def __init__(self, t_old, t, y_old, F):
+        super().__init__(t_old, t)
+        self.h = t - t_old
+        self.F = F
+        self.y_old = y_old
+
+    def _call_impl(self, t):
+        x = (t - self.t_old) / self.h
+
+        if t.ndim == 0:
+            y = np.zeros_like(self.y_old)
+        else:
+            x = x[:, None]
+            y = np.zeros((len(x), len(self.y_old)), dtype=self.y_old.dtype)
+
+        for i, f in enumerate(reversed(self.F)):
+            y += f
+            if i % 2 == 0:
+                y *= x
+            else:
+                y *= 1 - x
+        y += self.y_old
+
+        return y.T

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/tests/test_ivp.py

@@ -0,0 +1,1135 @@
+from itertools import product
+from numpy.testing import (assert_, assert_allclose, assert_array_less,
+                           assert_equal, assert_no_warnings, suppress_warnings)
+import pytest
+from pytest import raises as assert_raises
+import numpy as np
+from scipy.optimize._numdiff import group_columns
+from scipy.integrate import solve_ivp, RK23, RK45, DOP853, Radau, BDF, LSODA
+from scipy.integrate import OdeSolution
+from scipy.integrate._ivp.common import num_jac
+from scipy.integrate._ivp.base import ConstantDenseOutput
+from scipy.sparse import coo_matrix, csc_matrix
+
+
+def fun_zero(t, y):
+    return np.zeros_like(y)
+
+
+def fun_linear(t, y):
+    return np.array([-y[0] - 5 * y[1], y[0] + y[1]])
+
+
+def jac_linear():
+    return np.array([[-1, -5], [1, 1]])
+
+
+def sol_linear(t):
+    return np.vstack((-5 * np.sin(2 * t),
+                      2 * np.cos(2 * t) + np.sin(2 * t)))
+
+
+def fun_rational(t, y):
+    return np.array([y[1] / t,
+                     y[1] * (y[0] + 2 * y[1] - 1) / (t * (y[0] - 1))])
+
+
+def fun_rational_vectorized(t, y):
+    return np.vstack((y[1] / t,
+                      y[1] * (y[0] + 2 * y[1] - 1) / (t * (y[0] - 1))))
+
+
+def jac_rational(t, y):
+    return np.array([
+        [0, 1 / t],
+        [-2 * y[1] ** 2 / (t * (y[0] - 1) ** 2),
+         (y[0] + 4 * y[1] - 1) / (t * (y[0] - 1))]
+    ])
+
+
+def jac_rational_sparse(t, y):
+    return csc_matrix([
+        [0, 1 / t],
+        [-2 * y[1] ** 2 / (t * (y[0] - 1) ** 2),
+         (y[0] + 4 * y[1] - 1) / (t * (y[0] - 1))]
+    ])
+
+
+def sol_rational(t):
+    return np.asarray((t / (t + 10), 10 * t / (t + 10) ** 2))
+
+
+def fun_medazko(t, y):
+    n = y.shape[0] // 2
+    k = 100
+    c = 4
+
+    phi = 2 if t <= 5 else 0
+    y = np.hstack((phi, 0, y, y[-2]))
+
+    d = 1 / n
+    j = np.arange(n) + 1
+    alpha = 2 * (j * d - 1) ** 3 / c ** 2
+    beta = (j * d - 1) ** 4 / c ** 2
+
+    j_2_p1 = 2 * j + 2
+    j_2_m3 = 2 * j - 2
+    j_2_m1 = 2 * j
+    j_2 = 2 * j + 1
+
+    f = np.empty(2 * n)
+    f[::2] = (alpha * (y[j_2_p1] - y[j_2_m3]) / (2 * d) +
+              beta * (y[j_2_m3] - 2 * y[j_2_m1] + y[j_2_p1]) / d ** 2 -
+              k * y[j_2_m1] * y[j_2])
+    f[1::2] = -k * y[j_2] * y[j_2_m1]
+
+    return f
+
+
+def medazko_sparsity(n):
+    cols = []
+    rows = []
+
+    i = np.arange(n) * 2
+
+    cols.append(i[1:])
+    rows.append(i[1:] - 2)
+
+    cols.append(i)
+    rows.append(i)
+
+    cols.append(i)
+    rows.append(i + 1)
+
+    cols.append(i[:-1])
+    rows.append(i[:-1] + 2)
+
+    i = np.arange(n) * 2 + 1
+
+    cols.append(i)
+    rows.append(i)
+
+    cols.append(i)
+    rows.append(i - 1)
+
+    cols = np.hstack(cols)
+    rows = np.hstack(rows)
+
+    return coo_matrix((np.ones_like(cols), (cols, rows)))
+
+
+def fun_complex(t, y):
+    return -y
+
+
+def jac_complex(t, y):
+    return -np.eye(y.shape[0])
+
+
+def jac_complex_sparse(t, y):
+    return csc_matrix(jac_complex(t, y))
+
+
+def sol_complex(t):
+    y = (0.5 + 1j) * np.exp(-t)
+    return y.reshape((1, -1))
+
+
+def fun_event_dense_output_LSODA(t, y):
+    return y * (t - 2)
+
+
+def jac_event_dense_output_LSODA(t, y):
+    return t - 2
+
+
+def sol_event_dense_output_LSODA(t):
+    return np.exp(t ** 2 / 2 - 2 * t + np.log(0.05) - 6)
+
+
+def compute_error(y, y_true, rtol, atol):
+    e = (y - y_true) / (atol + rtol * np.abs(y_true))
+    return np.linalg.norm(e, axis=0) / np.sqrt(e.shape[0])
+
+
+def test_integration():
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [1/3, 2/9]
+
+    for vectorized, method, t_span, jac in product(
+            [False, True],
+            ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA'],
+            [[5, 9], [5, 1]],
+            [None, jac_rational, jac_rational_sparse]):
+
+        if vectorized:
+            fun = fun_rational_vectorized
+        else:
+            fun = fun_rational
+
+        with suppress_warnings() as sup:
+            sup.filter(UserWarning,
+                       "The following arguments have no effect for a chosen "
+                       "solver: `jac`")
+            res = solve_ivp(fun, t_span, y0, rtol=rtol,
+                            atol=atol, method=method, dense_output=True,
+                            jac=jac, vectorized=vectorized)
+        assert_equal(res.t[0], t_span[0])
+        assert_(res.t_events is None)
+        assert_(res.y_events is None)
+        assert_(res.success)
+        assert_equal(res.status, 0)
+
+        if method == 'DOP853':
+            # DOP853 spends more functions evaluation because it doesn't
+            # have enough time to develop big enough step size.
+            assert_(res.nfev < 50)
+        else:
+            assert_(res.nfev < 40)
+
+        if method in ['RK23', 'RK45', 'DOP853', 'LSODA']:
+            assert_equal(res.njev, 0)
+            assert_equal(res.nlu, 0)
+        else:
+            assert_(0 < res.njev < 3)
+            assert_(0 < res.nlu < 10)
+
+        y_true = sol_rational(res.t)
+        e = compute_error(res.y, y_true, rtol, atol)
+        assert_(np.all(e < 5))
+
+        tc = np.linspace(*t_span)
+        yc_true = sol_rational(tc)
+        yc = res.sol(tc)
+
+        e = compute_error(yc, yc_true, rtol, atol)
+        assert_(np.all(e < 5))
+
+        tc = (t_span[0] + t_span[-1]) / 2
+        yc_true = sol_rational(tc)
+        yc = res.sol(tc)
+
+        e = compute_error(yc, yc_true, rtol, atol)
+        assert_(np.all(e < 5))
+
+        assert_allclose(res.sol(res.t), res.y, rtol=1e-15, atol=1e-15)
+
+
+def test_integration_complex():
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [0.5 + 1j]
+    t_span = [0, 1]
+    tc = np.linspace(t_span[0], t_span[1])
+    for method, jac in product(['RK23', 'RK45', 'DOP853', 'BDF'],
+                               [None, jac_complex, jac_complex_sparse]):
+        with suppress_warnings() as sup:
+            sup.filter(UserWarning,
+                       "The following arguments have no effect for a chosen "
+                       "solver: `jac`")
+            res = solve_ivp(fun_complex, t_span, y0, method=method,
+                            dense_output=True, rtol=rtol, atol=atol, jac=jac)
+
+        assert_equal(res.t[0], t_span[0])
+        assert_(res.t_events is None)
+        assert_(res.y_events is None)
+        assert_(res.success)
+        assert_equal(res.status, 0)
+
+        if method == 'DOP853':
+            assert res.nfev < 35
+        else:
+            assert res.nfev < 25
+
+        if method == 'BDF':
+            assert_equal(res.njev, 1)
+            assert res.nlu < 6
+        else:
+            assert res.njev == 0
+            assert res.nlu == 0
+
+        y_true = sol_complex(res.t)
+        e = compute_error(res.y, y_true, rtol, atol)
+        assert np.all(e < 5)
+
+        yc_true = sol_complex(tc)
+        yc = res.sol(tc)
+        e = compute_error(yc, yc_true, rtol, atol)
+
+        assert np.all(e < 5)
+
+
+def test_integration_sparse_difference():
+    n = 200
+    t_span = [0, 20]
+    y0 = np.zeros(2 * n)
+    y0[1::2] = 1
+    sparsity = medazko_sparsity(n)
+
+    for method in ['BDF', 'Radau']:
+        res = solve_ivp(fun_medazko, t_span, y0, method=method,
+                        jac_sparsity=sparsity)
+
+        assert_equal(res.t[0], t_span[0])
+        assert_(res.t_events is None)
+        assert_(res.y_events is None)
+        assert_(res.success)
+        assert_equal(res.status, 0)
+
+        assert_allclose(res.y[78, -1], 0.233994e-3, rtol=1e-2)
+        assert_allclose(res.y[79, -1], 0, atol=1e-3)
+        assert_allclose(res.y[148, -1], 0.359561e-3, rtol=1e-2)
+        assert_allclose(res.y[149, -1], 0, atol=1e-3)
+        assert_allclose(res.y[198, -1], 0.117374129e-3, rtol=1e-2)
+        assert_allclose(res.y[199, -1], 0.6190807e-5, atol=1e-3)
+        assert_allclose(res.y[238, -1], 0, atol=1e-3)
+        assert_allclose(res.y[239, -1], 0.9999997, rtol=1e-2)
+
+
+def test_integration_const_jac():
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [0, 2]
+    t_span = [0, 2]
+    J = jac_linear()
+    J_sparse = csc_matrix(J)
+
+    for method, jac in product(['Radau', 'BDF'], [J, J_sparse]):
+        res = solve_ivp(fun_linear, t_span, y0, rtol=rtol, atol=atol,
+                        method=method, dense_output=True, jac=jac)
+        assert_equal(res.t[0], t_span[0])
+        assert_(res.t_events is None)
+        assert_(res.y_events is None)
+        assert_(res.success)
+        assert_equal(res.status, 0)
+
+        assert_(res.nfev < 100)
+        assert_equal(res.njev, 0)
+        assert_(0 < res.nlu < 15)
+
+        y_true = sol_linear(res.t)
+        e = compute_error(res.y, y_true, rtol, atol)
+        assert_(np.all(e < 10))
+
+        tc = np.linspace(*t_span)
+        yc_true = sol_linear(tc)
+        yc = res.sol(tc)
+
+        e = compute_error(yc, yc_true, rtol, atol)
+        assert_(np.all(e < 15))
+
+        assert_allclose(res.sol(res.t), res.y, rtol=1e-14, atol=1e-14)
+
+
+@pytest.mark.slow
+@pytest.mark.parametrize('method', ['Radau', 'BDF', 'LSODA'])
+def test_integration_stiff(method):
+    rtol = 1e-6
+    atol = 1e-6
+    y0 = [1e4, 0, 0]
+    tspan = [0, 1e8]
+
+    def fun_robertson(t, state):
+        x, y, z = state
+        return [
+            -0.04 * x + 1e4 * y * z,
+            0.04 * x - 1e4 * y * z - 3e7 * y * y,
+            3e7 * y * y,
+        ]
+
+    res = solve_ivp(fun_robertson, tspan, y0, rtol=rtol,
+                    atol=atol, method=method)
+
+    # If the stiff mode is not activated correctly, these numbers will be much bigger
+    assert res.nfev < 5000
+    assert res.njev < 200
+
+
+def test_events():
+    def event_rational_1(t, y):
+        return y[0] - y[1] ** 0.7
+
+    def event_rational_2(t, y):
+        return y[1] ** 0.6 - y[0]
+
+    def event_rational_3(t, y):
+        return t - 7.4
+
+    event_rational_3.terminal = True
+
+    for method in ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA']:
+        res = solve_ivp(fun_rational, [5, 8], [1/3, 2/9], method=method,
+                        events=(event_rational_1, event_rational_2))
+        assert_equal(res.status, 0)
+        assert_equal(res.t_events[0].size, 1)
+        assert_equal(res.t_events[1].size, 1)
+        assert_(5.3 < res.t_events[0][0] < 5.7)
+        assert_(7.3 < res.t_events[1][0] < 7.7)
+
+        assert_equal(res.y_events[0].shape, (1, 2))
+        assert_equal(res.y_events[1].shape, (1, 2))
+        assert np.isclose(
+            event_rational_1(res.t_events[0][0], res.y_events[0][0]), 0)
+        assert np.isclose(
+            event_rational_2(res.t_events[1][0], res.y_events[1][0]), 0)
+
+        event_rational_1.direction = 1
+        event_rational_2.direction = 1
+        res = solve_ivp(fun_rational, [5, 8], [1 / 3, 2 / 9], method=method,
+                        events=(event_rational_1, event_rational_2))
+        assert_equal(res.status, 0)
+        assert_equal(res.t_events[0].size, 1)
+        assert_equal(res.t_events[1].size, 0)
+        assert_(5.3 < res.t_events[0][0] < 5.7)
+        assert_equal(res.y_events[0].shape, (1, 2))
+        assert_equal(res.y_events[1].shape, (0,))
+        assert np.isclose(
+            event_rational_1(res.t_events[0][0], res.y_events[0][0]), 0)
+
+        event_rational_1.direction = -1
+        event_rational_2.direction = -1
+        res = solve_ivp(fun_rational, [5, 8], [1 / 3, 2 / 9], method=method,
+                        events=(event_rational_1, event_rational_2))
+        assert_equal(res.status, 0)
+        assert_equal(res.t_events[0].size, 0)
+        assert_equal(res.t_events[1].size, 1)
+        assert_(7.3 < res.t_events[1][0] < 7.7)
+        assert_equal(res.y_events[0].shape, (0,))
+        assert_equal(res.y_events[1].shape, (1, 2))
+        assert np.isclose(
+            event_rational_2(res.t_events[1][0], res.y_events[1][0]), 0)
+
+        event_rational_1.direction = 0
+        event_rational_2.direction = 0
+
+        res = solve_ivp(fun_rational, [5, 8], [1 / 3, 2 / 9], method=method,
+                        events=(event_rational_1, event_rational_2,
+                                event_rational_3), dense_output=True)
+        assert_equal(res.status, 1)
+        assert_equal(res.t_events[0].size, 1)
+        assert_equal(res.t_events[1].size, 0)
+        assert_equal(res.t_events[2].size, 1)
+        assert_(5.3 < res.t_events[0][0] < 5.7)
+        assert_(7.3 < res.t_events[2][0] < 7.5)
+        assert_equal(res.y_events[0].shape, (1, 2))
+        assert_equal(res.y_events[1].shape, (0,))
+        assert_equal(res.y_events[2].shape, (1, 2))
+        assert np.isclose(
+            event_rational_1(res.t_events[0][0], res.y_events[0][0]), 0)
+        assert np.isclose(
+            event_rational_3(res.t_events[2][0], res.y_events[2][0]), 0)
+
+        res = solve_ivp(fun_rational, [5, 8], [1 / 3, 2 / 9], method=method,
+                        events=event_rational_1, dense_output=True)
+        assert_equal(res.status, 0)
+        assert_equal(res.t_events[0].size, 1)
+        assert_(5.3 < res.t_events[0][0] < 5.7)
+
+        assert_equal(res.y_events[0].shape, (1, 2))
+        assert np.isclose(
+            event_rational_1(res.t_events[0][0], res.y_events[0][0]), 0)
+
+        # Also test that termination by event doesn't break interpolants.
+        tc = np.linspace(res.t[0], res.t[-1])
+        yc_true = sol_rational(tc)
+        yc = res.sol(tc)
+        e = compute_error(yc, yc_true, 1e-3, 1e-6)
+        assert_(np.all(e < 5))
+
+        # Test that the y_event matches solution
+        assert np.allclose(sol_rational(res.t_events[0][0]), res.y_events[0][0],
+                           rtol=1e-3, atol=1e-6)
+
+    # Test in backward direction.
+    event_rational_1.direction = 0
+    event_rational_2.direction = 0
+    for method in ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA']:
+        res = solve_ivp(fun_rational, [8, 5], [4/9, 20/81], method=method,
+                        events=(event_rational_1, event_rational_2))
+        assert_equal(res.status, 0)
+        assert_equal(res.t_events[0].size, 1)
+        assert_equal(res.t_events[1].size, 1)
+        assert_(5.3 < res.t_events[0][0] < 5.7)
+        assert_(7.3 < res.t_events[1][0] < 7.7)
+
+        assert_equal(res.y_events[0].shape, (1, 2))
+        assert_equal(res.y_events[1].shape, (1, 2))
+        assert np.isclose(
+            event_rational_1(res.t_events[0][0], res.y_events[0][0]), 0)
+        assert np.isclose(
+            event_rational_2(res.t_events[1][0], res.y_events[1][0]), 0)
+
+        event_rational_1.direction = -1
+        event_rational_2.direction = -1
+        res = solve_ivp(fun_rational, [8, 5], [4/9, 20/81], method=method,
+                        events=(event_rational_1, event_rational_2))
+        assert_equal(res.status, 0)
+        assert_equal(res.t_events[0].size, 1)
+        assert_equal(res.t_events[1].size, 0)
+        assert_(5.3 < res.t_events[0][0] < 5.7)
+
+        assert_equal(res.y_events[0].shape, (1, 2))
+        assert_equal(res.y_events[1].shape, (0,))
+        assert np.isclose(
+            event_rational_1(res.t_events[0][0], res.y_events[0][0]), 0)
+
+        event_rational_1.direction = 1
+        event_rational_2.direction = 1
+        res = solve_ivp(fun_rational, [8, 5], [4/9, 20/81], method=method,
+                        events=(event_rational_1, event_rational_2))
+        assert_equal(res.status, 0)
+        assert_equal(res.t_events[0].size, 0)
+        assert_equal(res.t_events[1].size, 1)
+        assert_(7.3 < res.t_events[1][0] < 7.7)
+
+        assert_equal(res.y_events[0].shape, (0,))
+        assert_equal(res.y_events[1].shape, (1, 2))
+        assert np.isclose(
+            event_rational_2(res.t_events[1][0], res.y_events[1][0]), 0)
+
+        event_rational_1.direction = 0
+        event_rational_2.direction = 0
+
+        res = solve_ivp(fun_rational, [8, 5], [4/9, 20/81], method=method,
+                        events=(event_rational_1, event_rational_2,
+                                event_rational_3), dense_output=True)
+        assert_equal(res.status, 1)
+        assert_equal(res.t_events[0].size, 0)
+        assert_equal(res.t_events[1].size, 1)
+        assert_equal(res.t_events[2].size, 1)
+        assert_(7.3 < res.t_events[1][0] < 7.7)
+        assert_(7.3 < res.t_events[2][0] < 7.5)
+
+        assert_equal(res.y_events[0].shape, (0,))
+        assert_equal(res.y_events[1].shape, (1, 2))
+        assert_equal(res.y_events[2].shape, (1, 2))
+        assert np.isclose(
+            event_rational_2(res.t_events[1][0], res.y_events[1][0]), 0)
+        assert np.isclose(
+            event_rational_3(res.t_events[2][0], res.y_events[2][0]), 0)
+
+        # Also test that termination by event doesn't break interpolants.
+        tc = np.linspace(res.t[-1], res.t[0])
+        yc_true = sol_rational(tc)
+        yc = res.sol(tc)
+        e = compute_error(yc, yc_true, 1e-3, 1e-6)
+        assert_(np.all(e < 5))
+
+        assert np.allclose(sol_rational(res.t_events[1][0]), res.y_events[1][0],
+                           rtol=1e-3, atol=1e-6)
+        assert np.allclose(sol_rational(res.t_events[2][0]), res.y_events[2][0],
+                           rtol=1e-3, atol=1e-6)
+
+
+def _get_harmonic_oscillator():
+    def f(t, y):
+        return [y[1], -y[0]]
+
+    def event(t, y):
+        return y[0]
+
+    return f, event
+
+
+@pytest.mark.parametrize('n_events', [3, 4])
+def test_event_terminal_integer(n_events):
+    f, event = _get_harmonic_oscillator()
+    event.terminal = n_events
+    res = solve_ivp(f, (0, 100), [1, 0], events=event)
+    assert len(res.t_events[0]) == n_events
+    assert len(res.y_events[0]) == n_events
+    assert_allclose(res.y_events[0][:, 0], 0, atol=1e-14)
+
+
+def test_event_terminal_iv():
+    f, event = _get_harmonic_oscillator()
+    args = (f, (0, 100), [1, 0])
+
+    event.terminal = None
+    res = solve_ivp(*args, events=event)
+    event.terminal = 0
+    ref = solve_ivp(*args, events=event)
+    assert_allclose(res.t_events, ref.t_events)
+
+    message = "The `terminal` attribute..."
+    event.terminal = -1
+    with pytest.raises(ValueError, match=message):
+        solve_ivp(*args, events=event)
+    event.terminal = 3.5
+    with pytest.raises(ValueError, match=message):
+        solve_ivp(*args, events=event)
+
+
+def test_max_step():
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [1/3, 2/9]
+    for method in [RK23, RK45, DOP853, Radau, BDF, LSODA]:
+        for t_span in ([5, 9], [5, 1]):
+            res = solve_ivp(fun_rational, t_span, y0, rtol=rtol,
+                            max_step=0.5, atol=atol, method=method,
+                            dense_output=True)
+            assert_equal(res.t[0], t_span[0])
+            assert_equal(res.t[-1], t_span[-1])
+            assert_(np.all(np.abs(np.diff(res.t)) <= 0.5 + 1e-15))
+            assert_(res.t_events is None)
+            assert_(res.success)
+            assert_equal(res.status, 0)
+
+            y_true = sol_rational(res.t)
+            e = compute_error(res.y, y_true, rtol, atol)
+            assert_(np.all(e < 5))
+
+            tc = np.linspace(*t_span)
+            yc_true = sol_rational(tc)
+            yc = res.sol(tc)
+
+            e = compute_error(yc, yc_true, rtol, atol)
+            assert_(np.all(e < 5))
+
+            assert_allclose(res.sol(res.t), res.y, rtol=1e-15, atol=1e-15)
+
+            assert_raises(ValueError, method, fun_rational, t_span[0], y0,
+                          t_span[1], max_step=-1)
+
+            if method is not LSODA:
+                solver = method(fun_rational, t_span[0], y0, t_span[1],
+                                rtol=rtol, atol=atol, max_step=1e-20)
+                message = solver.step()
+
+                assert_equal(solver.status, 'failed')
+                assert_("step size is less" in message)
+                assert_raises(RuntimeError, solver.step)
+
+
+def test_first_step():
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [1/3, 2/9]
+    first_step = 0.1
+    for method in [RK23, RK45, DOP853, Radau, BDF, LSODA]:
+        for t_span in ([5, 9], [5, 1]):
+            res = solve_ivp(fun_rational, t_span, y0, rtol=rtol,
+                            max_step=0.5, atol=atol, method=method,
+                            dense_output=True, first_step=first_step)
+
+            assert_equal(res.t[0], t_span[0])
+            assert_equal(res.t[-1], t_span[-1])
+            assert_allclose(first_step, np.abs(res.t[1] - 5))
+            assert_(res.t_events is None)
+            assert_(res.success)
+            assert_equal(res.status, 0)
+
+            y_true = sol_rational(res.t)
+            e = compute_error(res.y, y_true, rtol, atol)
+            assert_(np.all(e < 5))
+
+            tc = np.linspace(*t_span)
+            yc_true = sol_rational(tc)
+            yc = res.sol(tc)
+
+            e = compute_error(yc, yc_true, rtol, atol)
+            assert_(np.all(e < 5))
+
+            assert_allclose(res.sol(res.t), res.y, rtol=1e-15, atol=1e-15)
+
+            assert_raises(ValueError, method, fun_rational, t_span[0], y0,
+                          t_span[1], first_step=-1)
+            assert_raises(ValueError, method, fun_rational, t_span[0], y0,
+                          t_span[1], first_step=5)
+
+
+def test_t_eval():
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [1/3, 2/9]
+    for t_span in ([5, 9], [5, 1]):
+        t_eval = np.linspace(t_span[0], t_span[1], 10)
+        res = solve_ivp(fun_rational, t_span, y0, rtol=rtol, atol=atol,
+                        t_eval=t_eval)
+        assert_equal(res.t, t_eval)
+        assert_(res.t_events is None)
+        assert_(res.success)
+        assert_equal(res.status, 0)
+
+        y_true = sol_rational(res.t)
+        e = compute_error(res.y, y_true, rtol, atol)
+        assert_(np.all(e < 5))
+
+    t_eval = [5, 5.01, 7, 8, 8.01, 9]
+    res = solve_ivp(fun_rational, [5, 9], y0, rtol=rtol, atol=atol,
+                    t_eval=t_eval)
+    assert_equal(res.t, t_eval)
+    assert_(res.t_events is None)
+    assert_(res.success)
+    assert_equal(res.status, 0)
+
+    y_true = sol_rational(res.t)
+    e = compute_error(res.y, y_true, rtol, atol)
+    assert_(np.all(e < 5))
+
+    t_eval = [5, 4.99, 3, 1.5, 1.1, 1.01, 1]
+    res = solve_ivp(fun_rational, [5, 1], y0, rtol=rtol, atol=atol,
+                    t_eval=t_eval)
+    assert_equal(res.t, t_eval)
+    assert_(res.t_events is None)
+    assert_(res.success)
+    assert_equal(res.status, 0)
+
+    t_eval = [5.01, 7, 8, 8.01]
+    res = solve_ivp(fun_rational, [5, 9], y0, rtol=rtol, atol=atol,
+                    t_eval=t_eval)
+    assert_equal(res.t, t_eval)
+    assert_(res.t_events is None)
+    assert_(res.success)
+    assert_equal(res.status, 0)
+
+    y_true = sol_rational(res.t)
+    e = compute_error(res.y, y_true, rtol, atol)
+    assert_(np.all(e < 5))
+
+    t_eval = [4.99, 3, 1.5, 1.1, 1.01]
+    res = solve_ivp(fun_rational, [5, 1], y0, rtol=rtol, atol=atol,
+                    t_eval=t_eval)
+    assert_equal(res.t, t_eval)
+    assert_(res.t_events is None)
+    assert_(res.success)
+    assert_equal(res.status, 0)
+
+    t_eval = [4, 6]
+    assert_raises(ValueError, solve_ivp, fun_rational, [5, 9], y0,
+                  rtol=rtol, atol=atol, t_eval=t_eval)
+
+
+def test_t_eval_dense_output():
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [1/3, 2/9]
+    t_span = [5, 9]
+    t_eval = np.linspace(t_span[0], t_span[1], 10)
+    res = solve_ivp(fun_rational, t_span, y0, rtol=rtol, atol=atol,
+                    t_eval=t_eval)
+    res_d = solve_ivp(fun_rational, t_span, y0, rtol=rtol, atol=atol,
+                      t_eval=t_eval, dense_output=True)
+    assert_equal(res.t, t_eval)
+    assert_(res.t_events is None)
+    assert_(res.success)
+    assert_equal(res.status, 0)
+
+    assert_equal(res.t, res_d.t)
+    assert_equal(res.y, res_d.y)
+    assert_(res_d.t_events is None)
+    assert_(res_d.success)
+    assert_equal(res_d.status, 0)
+
+    # if t and y are equal only test values for one case
+    y_true = sol_rational(res.t)
+    e = compute_error(res.y, y_true, rtol, atol)
+    assert_(np.all(e < 5))
+
+
+def test_t_eval_early_event():
+    def early_event(t, y):
+        return t - 7
+
+    early_event.terminal = True
+
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [1/3, 2/9]
+    t_span = [5, 9]
+    t_eval = np.linspace(7.5, 9, 16)
+    for method in ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA']:
+        with suppress_warnings() as sup:
+            sup.filter(UserWarning,
+                       "The following arguments have no effect for a chosen "
+                       "solver: `jac`")
+            res = solve_ivp(fun_rational, t_span, y0, rtol=rtol, atol=atol,
+                            method=method, t_eval=t_eval, events=early_event,
+                            jac=jac_rational)
+        assert res.success
+        assert res.message == 'A termination event occurred.'
+        assert res.status == 1
+        assert not res.t and not res.y
+        assert len(res.t_events) == 1
+        assert res.t_events[0].size == 1
+        assert res.t_events[0][0] == 7
+
+
+def test_event_dense_output_LSODA():
+    def event_lsoda(t, y):
+        return y[0] - 2.02e-5
+
+    rtol = 1e-3
+    atol = 1e-6
+    y0 = [0.05]
+    t_span = [-2, 2]
+    first_step = 1e-3
+    res = solve_ivp(
+        fun_event_dense_output_LSODA,
+        t_span,
+        y0,
+        method="LSODA",
+        dense_output=True,
+        events=event_lsoda,
+        first_step=first_step,
+        max_step=1,
+        rtol=rtol,
+        atol=atol,
+        jac=jac_event_dense_output_LSODA,
+    )
+
+    assert_equal(res.t[0], t_span[0])
+    assert_equal(res.t[-1], t_span[-1])
+    assert_allclose(first_step, np.abs(res.t[1] - t_span[0]))
+    assert res.success
+    assert_equal(res.status, 0)
+
+    y_true = sol_event_dense_output_LSODA(res.t)
+    e = compute_error(res.y, y_true, rtol, atol)
+    assert_array_less(e, 5)
+
+    tc = np.linspace(*t_span)
+    yc_true = sol_event_dense_output_LSODA(tc)
+    yc = res.sol(tc)
+    e = compute_error(yc, yc_true, rtol, atol)
+    assert_array_less(e, 5)
+
+    assert_allclose(res.sol(res.t), res.y, rtol=1e-15, atol=1e-15)
+
+
+def test_no_integration():
+    for method in ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA']:
+        sol = solve_ivp(lambda t, y: -y, [4, 4], [2, 3],
+                        method=method, dense_output=True)
+        assert_equal(sol.sol(4), [2, 3])
+        assert_equal(sol.sol([4, 5, 6]), [[2, 2, 2], [3, 3, 3]])
+
+
+def test_no_integration_class():
+    for method in [RK23, RK45, DOP853, Radau, BDF, LSODA]:
+        solver = method(lambda t, y: -y, 0.0, [10.0, 0.0], 0.0)
+        solver.step()
+        assert_equal(solver.status, 'finished')
+        sol = solver.dense_output()
+        assert_equal(sol(0.0), [10.0, 0.0])
+        assert_equal(sol([0, 1, 2]), [[10, 10, 10], [0, 0, 0]])
+
+        solver = method(lambda t, y: -y, 0.0, [], np.inf)
+        solver.step()
+        assert_equal(solver.status, 'finished')
+        sol = solver.dense_output()
+        assert_equal(sol(100.0), [])
+        assert_equal(sol([0, 1, 2]), np.empty((0, 3)))
+
+
+def test_empty():
+    def fun(t, y):
+        return np.zeros((0,))
+
+    y0 = np.zeros((0,))
+
+    for method in ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA']:
+        sol = assert_no_warnings(solve_ivp, fun, [0, 10], y0,
+                                 method=method, dense_output=True)
+        assert_equal(sol.sol(10), np.zeros((0,)))
+        assert_equal(sol.sol([1, 2, 3]), np.zeros((0, 3)))
+
+    for method in ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA']:
+        sol = assert_no_warnings(solve_ivp, fun, [0, np.inf], y0,
+                                 method=method, dense_output=True)
+        assert_equal(sol.sol(10), np.zeros((0,)))
+        assert_equal(sol.sol([1, 2, 3]), np.zeros((0, 3)))
+
+
+def test_ConstantDenseOutput():
+    sol = ConstantDenseOutput(0, 1, np.array([1, 2]))
+    assert_allclose(sol(1.5), [1, 2])
+    assert_allclose(sol([1, 1.5, 2]), [[1, 1, 1], [2, 2, 2]])
+
+    sol = ConstantDenseOutput(0, 1, np.array([]))
+    assert_allclose(sol(1.5), np.empty(0))
+    assert_allclose(sol([1, 1.5, 2]), np.empty((0, 3)))
+
+
+def test_classes():
+    y0 = [1 / 3, 2 / 9]
+    for cls in [RK23, RK45, DOP853, Radau, BDF, LSODA]:
+        solver = cls(fun_rational, 5, y0, np.inf)
+        assert_equal(solver.n, 2)
+        assert_equal(solver.status, 'running')
+        assert_equal(solver.t_bound, np.inf)
+        assert_equal(solver.direction, 1)
+        assert_equal(solver.t, 5)
+        assert_equal(solver.y, y0)
+        assert_(solver.step_size is None)
+        if cls is not LSODA:
+            assert_(solver.nfev > 0)
+            assert_(solver.njev >= 0)
+            assert_equal(solver.nlu, 0)
+        else:
+            assert_equal(solver.nfev, 0)
+            assert_equal(solver.njev, 0)
+            assert_equal(solver.nlu, 0)
+
+        assert_raises(RuntimeError, solver.dense_output)
+
+        message = solver.step()
+        assert_equal(solver.status, 'running')
+        assert_equal(message, None)
+        assert_equal(solver.n, 2)
+        assert_equal(solver.t_bound, np.inf)
+        assert_equal(solver.direction, 1)
+        assert_(solver.t > 5)
+        assert_(not np.all(np.equal(solver.y, y0)))
+        assert_(solver.step_size > 0)
+        assert_(solver.nfev > 0)
+        assert_(solver.njev >= 0)
+        assert_(solver.nlu >= 0)
+        sol = solver.dense_output()
+        assert_allclose(sol(5), y0, rtol=1e-15, atol=0)
+
+
+def test_OdeSolution():
+    ts = np.array([0, 2, 5], dtype=float)
+    s1 = ConstantDenseOutput(ts[0], ts[1], np.array([-1]))
+    s2 = ConstantDenseOutput(ts[1], ts[2], np.array([1]))
+
+    sol = OdeSolution(ts, [s1, s2])
+
+    assert_equal(sol(-1), [-1])
+    assert_equal(sol(1), [-1])
+    assert_equal(sol(2), [-1])
+    assert_equal(sol(3), [1])
+    assert_equal(sol(5), [1])
+    assert_equal(sol(6), [1])
+
+    assert_equal(sol([0, 6, -2, 1.5, 4.5, 2.5, 5, 5.5, 2]),
+                 np.array([[-1, 1, -1, -1, 1, 1, 1, 1, -1]]))
+
+    ts = np.array([10, 4, -3])
+    s1 = ConstantDenseOutput(ts[0], ts[1], np.array([-1]))
+    s2 = ConstantDenseOutput(ts[1], ts[2], np.array([1]))
+
+    sol = OdeSolution(ts, [s1, s2])
+    assert_equal(sol(11), [-1])
+    assert_equal(sol(10), [-1])
+    assert_equal(sol(5), [-1])
+    assert_equal(sol(4), [-1])
+    assert_equal(sol(0), [1])
+    assert_equal(sol(-3), [1])
+    assert_equal(sol(-4), [1])
+
+    assert_equal(sol([12, -5, 10, -3, 6, 1, 4]),
+                 np.array([[-1, 1, -1, 1, -1, 1, -1]]))
+
+    ts = np.array([1, 1])
+    s = ConstantDenseOutput(1, 1, np.array([10]))
+    sol = OdeSolution(ts, [s])
+    assert_equal(sol(0), [10])
+    assert_equal(sol(1), [10])
+    assert_equal(sol(2), [10])
+
+    assert_equal(sol([2, 1, 0]), np.array([[10, 10, 10]]))
+
+
+def test_num_jac():
+    def fun(t, y):
+        return np.vstack([
+            -0.04 * y[0] + 1e4 * y[1] * y[2],
+            0.04 * y[0] - 1e4 * y[1] * y[2] - 3e7 * y[1] ** 2,
+            3e7 * y[1] ** 2
+        ])
+
+    def jac(t, y):
+        return np.array([
+            [-0.04, 1e4 * y[2], 1e4 * y[1]],
+            [0.04, -1e4 * y[2] - 6e7 * y[1], -1e4 * y[1]],
+            [0, 6e7 * y[1], 0]
+        ])
+
+    t = 1
+    y = np.array([1, 0, 0])
+    J_true = jac(t, y)
+    threshold = 1e-5
+    f = fun(t, y).ravel()
+
+    J_num, factor = num_jac(fun, t, y, f, threshold, None)
+    assert_allclose(J_num, J_true, rtol=1e-5, atol=1e-5)
+
+    J_num, factor = num_jac(fun, t, y, f, threshold, factor)
+    assert_allclose(J_num, J_true, rtol=1e-5, atol=1e-5)
+
+
+def test_num_jac_sparse():
+    def fun(t, y):
+        e = y[1:]**3 - y[:-1]**2
+        z = np.zeros(y.shape[1])
+        return np.vstack((z, 3 * e)) + np.vstack((2 * e, z))
+
+    def structure(n):
+        A = np.zeros((n, n), dtype=int)
+        A[0, 0] = 1
+        A[0, 1] = 1
+        for i in range(1, n - 1):
+            A[i, i - 1: i + 2] = 1
+        A[-1, -1] = 1
+        A[-1, -2] = 1
+
+        return A
+
+    np.random.seed(0)
+    n = 20
+    y = np.random.randn(n)
+    A = structure(n)
+    groups = group_columns(A)
+
+    f = fun(0, y[:, None]).ravel()
+
+    # Compare dense and sparse results, assuming that dense implementation
+    # is correct (as it is straightforward).
+    J_num_sparse, factor_sparse = num_jac(fun, 0, y.ravel(), f, 1e-8, None,
+                                          sparsity=(A, groups))
+    J_num_dense, factor_dense = num_jac(fun, 0, y.ravel(), f, 1e-8, None)
+    assert_allclose(J_num_dense, J_num_sparse.toarray(),
+                    rtol=1e-12, atol=1e-14)
+    assert_allclose(factor_dense, factor_sparse, rtol=1e-12, atol=1e-14)
+
+    # Take small factors to trigger their recomputing inside.
+    factor = np.random.uniform(0, 1e-12, size=n)
+    J_num_sparse, factor_sparse = num_jac(fun, 0, y.ravel(), f, 1e-8, factor,
+                                          sparsity=(A, groups))
+    J_num_dense, factor_dense = num_jac(fun, 0, y.ravel(), f, 1e-8, factor)
+
+    assert_allclose(J_num_dense, J_num_sparse.toarray(),
+                    rtol=1e-12, atol=1e-14)
+    assert_allclose(factor_dense, factor_sparse, rtol=1e-12, atol=1e-14)
+
+
+def test_args():
+
+    # sys3 is actually two decoupled systems. (x, y) form a
+    # linear oscillator, while z is a nonlinear first order
+    # system with equilibria at z=0 and z=1. If k > 0, z=1
+    # is stable and z=0 is unstable.
+
+    def sys3(t, w, omega, k, zfinal):
+        x, y, z = w
+        return [-omega*y, omega*x, k*z*(1 - z)]
+
+    def sys3_jac(t, w, omega, k, zfinal):
+        x, y, z = w
+        J = np.array([[0, -omega, 0],
+                      [omega, 0, 0],
+                      [0, 0, k*(1 - 2*z)]])
+        return J
+
+    def sys3_x0decreasing(t, w, omega, k, zfinal):
+        x, y, z = w
+        return x
+
+    def sys3_y0increasing(t, w, omega, k, zfinal):
+        x, y, z = w
+        return y
+
+    def sys3_zfinal(t, w, omega, k, zfinal):
+        x, y, z = w
+        return z - zfinal
+
+    # Set the event flags for the event functions.
+    sys3_x0decreasing.direction = -1
+    sys3_y0increasing.direction = 1
+    sys3_zfinal.terminal = True
+
+    omega = 2
+    k = 4
+
+    tfinal = 5
+    zfinal = 0.99
+    # Find z0 such that when z(0) = z0, z(tfinal) = zfinal.
+    # The condition z(tfinal) = zfinal is the terminal event.
+    z0 = np.exp(-k*tfinal)/((1 - zfinal)/zfinal + np.exp(-k*tfinal))
+
+    w0 = [0, -1, z0]
+
+    # Provide the jac argument and use the Radau method to ensure that the use
+    # of the Jacobian function is exercised.
+    # If event handling is working, the solution will stop at tfinal, not tend.
+    tend = 2*tfinal
+    sol = solve_ivp(sys3, [0, tend], w0,
+                    events=[sys3_x0decreasing, sys3_y0increasing, sys3_zfinal],
+                    dense_output=True, args=(omega, k, zfinal),
+                    method='Radau', jac=sys3_jac,
+                    rtol=1e-10, atol=1e-13)
+
+    # Check that we got the expected events at the expected times.
+    x0events_t = sol.t_events[0]
+    y0events_t = sol.t_events[1]
+    zfinalevents_t = sol.t_events[2]
+    assert_allclose(x0events_t, [0.5*np.pi, 1.5*np.pi])
+    assert_allclose(y0events_t, [0.25*np.pi, 1.25*np.pi])
+    assert_allclose(zfinalevents_t, [tfinal])
+
+    # Check that the solution agrees with the known exact solution.
+    t = np.linspace(0, zfinalevents_t[0], 250)
+    w = sol.sol(t)
+    assert_allclose(w[0], np.sin(omega*t), rtol=1e-9, atol=1e-12)
+    assert_allclose(w[1], -np.cos(omega*t), rtol=1e-9, atol=1e-12)
+    assert_allclose(w[2], 1/(((1 - z0)/z0)*np.exp(-k*t) + 1),
+                    rtol=1e-9, atol=1e-12)
+
+    # Check that the state variables have the expected values at the events.
+    x0events = sol.sol(x0events_t)
+    y0events = sol.sol(y0events_t)
+    zfinalevents = sol.sol(zfinalevents_t)
+    assert_allclose(x0events[0], np.zeros_like(x0events[0]), atol=5e-14)
+    assert_allclose(x0events[1], np.ones_like(x0events[1]))
+    assert_allclose(y0events[0], np.ones_like(y0events[0]))
+    assert_allclose(y0events[1], np.zeros_like(y0events[1]), atol=5e-14)
+    assert_allclose(zfinalevents[2], [zfinal])
+
+
+def test_array_rtol():
+    # solve_ivp had a bug with array_like `rtol`; see gh-15482
+    # check that it's fixed
+    def f(t, y):
+        return y[0], y[1]
+
+    # no warning (or error) when `rtol` is array_like
+    sol = solve_ivp(f, (0, 1), [1., 1.], rtol=[1e-1, 1e-1])
+    err1 = np.abs(np.linalg.norm(sol.y[:, -1] - np.exp(1)))
+
+    # warning when an element of `rtol` is too small
+    with pytest.warns(UserWarning, match="At least one element..."):
+        sol = solve_ivp(f, (0, 1), [1., 1.], rtol=[1e-1, 1e-16])
+        err2 = np.abs(np.linalg.norm(sol.y[:, -1] - np.exp(1)))
+
+    # tighter rtol improves the error
+    assert err2 < err1
+
+@pytest.mark.parametrize('method', ['RK23', 'RK45', 'DOP853', 'Radau', 'BDF', 'LSODA'])
+def test_integration_zero_rhs(method):
+    result = solve_ivp(fun_zero, [0, 10], np.ones(3), method=method)
+    assert_(result.success)
+    assert_equal(result.status, 0)
+    assert_allclose(result.y, 1.0, rtol=1e-15)
+
+
+def test_args_single_value():
+    def fun_with_arg(t, y, a):
+        return a*y
+
+    message = "Supplied 'args' cannot be unpacked."
+    with pytest.raises(TypeError, match=message):
+        solve_ivp(fun_with_arg, (0, 0.1), [1], args=-1)
+
+    sol = solve_ivp(fun_with_arg, (0, 0.1), [1], args=(-1,))
+    assert_allclose(sol.y[0, -1], np.exp(-0.1))
+
+@pytest.mark.parametrize("f0_fill", [np.nan, np.inf])
+def test_initial_state_finiteness(f0_fill):
+    # regression test for gh-17846
+    msg = "All components of the initial state `y0` must be finite."
+    with pytest.raises(ValueError, match=msg):
+        solve_ivp(fun_zero, [0, 10], np.full(3, f0_fill))

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ivp/tests/test_rk.py

@@ -0,0 +1,37 @@
+import pytest
+from numpy.testing import assert_allclose, assert_
+import numpy as np
+from scipy.integrate import RK23, RK45, DOP853
+from scipy.integrate._ivp import dop853_coefficients
+
+
+@pytest.mark.parametrize("solver", [RK23, RK45, DOP853])
+def test_coefficient_properties(solver):
+    assert_allclose(np.sum(solver.B), 1, rtol=1e-15)
+    assert_allclose(np.sum(solver.A, axis=1), solver.C, rtol=1e-14)
+
+
+def test_coefficient_properties_dop853():
+    assert_allclose(np.sum(dop853_coefficients.B), 1, rtol=1e-15)
+    assert_allclose(np.sum(dop853_coefficients.A, axis=1),
+                    dop853_coefficients.C,
+                    rtol=1e-14)
+
+
+@pytest.mark.parametrize("solver_class", [RK23, RK45, DOP853])
+def test_error_estimation(solver_class):
+    step = 0.2
+    solver = solver_class(lambda t, y: y, 0, [1], 1, first_step=step)
+    solver.step()
+    error_estimate = solver._estimate_error(solver.K, step)
+    error = solver.y - np.exp([step])
+    assert_(np.abs(error) < np.abs(error_estimate))
+
+
+@pytest.mark.parametrize("solver_class", [RK23, RK45, DOP853])
+def test_error_estimation_complex(solver_class):
+    h = 0.2
+    solver = solver_class(lambda t, y: 1j * y, 0, [1j], 1, first_step=h)
+    solver.step()
+    err_norm = solver._estimate_error_norm(solver.K, h, scale=[1])
+    assert np.isrealobj(err_norm)

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_ode.py

@@ -0,0 +1,1376 @@
+# Authors: Pearu Peterson, Pauli Virtanen, John Travers
+"""
+First-order ODE integrators.
+
+User-friendly interface to various numerical integrators for solving a
+system of first order ODEs with prescribed initial conditions::
+
+    d y(t)[i]
+    ---------  = f(t,y(t))[i],
+       d t
+
+    y(t=0)[i] = y0[i],
+
+where::
+
+    i = 0, ..., len(y0) - 1
+
+class ode
+---------
+
+A generic interface class to numeric integrators. It has the following
+methods::
+
+    integrator = ode(f, jac=None)
+    integrator = integrator.set_integrator(name, **params)
+    integrator = integrator.set_initial_value(y0, t0=0.0)
+    integrator = integrator.set_f_params(*args)
+    integrator = integrator.set_jac_params(*args)
+    y1 = integrator.integrate(t1, step=False, relax=False)
+    flag = integrator.successful()
+
+class complex_ode
+-----------------
+
+This class has the same generic interface as ode, except it can handle complex
+f, y and Jacobians by transparently translating them into the equivalent
+real-valued system. It supports the real-valued solvers (i.e., not zvode) and is
+an alternative to ode with the zvode solver, sometimes performing better.
+"""
+# XXX: Integrators must have:
+# ===========================
+# cvode - C version of vode and vodpk with many improvements.
+#   Get it from http://www.netlib.org/ode/cvode.tar.gz.
+#   To wrap cvode to Python, one must write the extension module by
+#   hand. Its interface is too much 'advanced C' that using f2py
+#   would be too complicated (or impossible).
+#
+# How to define a new integrator:
+# ===============================
+#
+# class myodeint(IntegratorBase):
+#
+#     runner = <odeint function> or None
+#
+#     def __init__(self,...):                           # required
+#         <initialize>
+#
+#     def reset(self,n,has_jac):                        # optional
+#         # n - the size of the problem (number of equations)
+#         # has_jac - whether user has supplied its own routine for Jacobian
+#         <allocate memory,initialize further>
+#
+#     def run(self,f,jac,y0,t0,t1,f_params,jac_params): # required
+#         # this method is called to integrate from t=t0 to t=t1
+#         # with initial condition y0. f and jac are user-supplied functions
+#         # that define the problem. f_params,jac_params are additional
+#         # arguments
+#         # to these functions.
+#         <calculate y1>
+#         if <calculation was unsuccessful>:
+#             self.success = 0
+#         return t1,y1
+#
+#     # In addition, one can define step() and run_relax() methods (they
+#     # take the same arguments as run()) if the integrator can support
+#     # these features (see IntegratorBase doc strings).
+#
+# if myodeint.runner:
+#     IntegratorBase.integrator_classes.append(myodeint)
+
+__all__ = ['ode', 'complex_ode']
+
+import re
+import warnings
+
+from numpy import asarray, array, zeros, isscalar, real, imag, vstack
+
+from . import _vode
+from . import _dop
+from . import _lsoda
+
+
+_dop_int_dtype = _dop.types.intvar.dtype
+_vode_int_dtype = _vode.types.intvar.dtype
+_lsoda_int_dtype = _lsoda.types.intvar.dtype
+
+
+# ------------------------------------------------------------------------------
+# User interface
+# ------------------------------------------------------------------------------
+
+
+class ode:
+    """
+    A generic interface class to numeric integrators.
+
+    Solve an equation system :math:`y'(t) = f(t,y)` with (optional) ``jac = df/dy``.
+
+    *Note*: The first two arguments of ``f(t, y, ...)`` are in the
+    opposite order of the arguments in the system definition function used
+    by `scipy.integrate.odeint`.
+
+    Parameters
+    ----------
+    f : callable ``f(t, y, *f_args)``
+        Right-hand side of the differential equation. t is a scalar,
+        ``y.shape == (n,)``.
+        ``f_args`` is set by calling ``set_f_params(*args)``.
+        `f` should return a scalar, array or list (not a tuple).
+    jac : callable ``jac(t, y, *jac_args)``, optional
+        Jacobian of the right-hand side, ``jac[i,j] = d f[i] / d y[j]``.
+        ``jac_args`` is set by calling ``set_jac_params(*args)``.
+
+    Attributes
+    ----------
+    t : float
+        Current time.
+    y : ndarray
+        Current variable values.
+
+    See also
+    --------
+    odeint : an integrator with a simpler interface based on lsoda from ODEPACK
+    quad : for finding the area under a curve
+
+    Notes
+    -----
+    Available integrators are listed below. They can be selected using
+    the `set_integrator` method.
+
+    "vode"
+
+        Real-valued Variable-coefficient Ordinary Differential Equation
+        solver, with fixed-leading-coefficient implementation. It provides
+        implicit Adams method (for non-stiff problems) and a method based on
+        backward differentiation formulas (BDF) (for stiff problems).
+
+        Source: http://www.netlib.org/ode/vode.f
+
+        .. warning::
+
+           This integrator is not re-entrant. You cannot have two `ode`
+           instances using the "vode" integrator at the same time.
+
+        This integrator accepts the following parameters in `set_integrator`
+        method of the `ode` class:
+
+        - atol : float or sequence
+          absolute tolerance for solution
+        - rtol : float or sequence
+          relative tolerance for solution
+        - lband : None or int
+        - uband : None or int
+          Jacobian band width, jac[i,j] != 0 for i-lband <= j <= i+uband.
+          Setting these requires your jac routine to return the jacobian
+          in packed format, jac_packed[i-j+uband, j] = jac[i,j]. The
+          dimension of the matrix must be (lband+uband+1, len(y)).
+        - method: 'adams' or 'bdf'
+          Which solver to use, Adams (non-stiff) or BDF (stiff)
+        - with_jacobian : bool
+          This option is only considered when the user has not supplied a
+          Jacobian function and has not indicated (by setting either band)
+          that the Jacobian is banded. In this case, `with_jacobian` specifies
+          whether the iteration method of the ODE solver's correction step is
+          chord iteration with an internally generated full Jacobian or
+          functional iteration with no Jacobian.
+        - nsteps : int
+          Maximum number of (internally defined) steps allowed during one
+          call to the solver.
+        - first_step : float
+        - min_step : float
+        - max_step : float
+          Limits for the step sizes used by the integrator.
+        - order : int
+          Maximum order used by the integrator,
+          order <= 12 for Adams, <= 5 for BDF.
+
+    "zvode"
+
+        Complex-valued Variable-coefficient Ordinary Differential Equation
+        solver, with fixed-leading-coefficient implementation. It provides
+        implicit Adams method (for non-stiff problems) and a method based on
+        backward differentiation formulas (BDF) (for stiff problems).
+
+        Source: http://www.netlib.org/ode/zvode.f
+
+        .. warning::
+
+           This integrator is not re-entrant. You cannot have two `ode`
+           instances using the "zvode" integrator at the same time.
+
+        This integrator accepts the same parameters in `set_integrator`
+        as the "vode" solver.
+
+        .. note::
+
+            When using ZVODE for a stiff system, it should only be used for
+            the case in which the function f is analytic, that is, when each f(i)
+            is an analytic function of each y(j). Analyticity means that the
+            partial derivative df(i)/dy(j) is a unique complex number, and this
+            fact is critical in the way ZVODE solves the dense or banded linear
+            systems that arise in the stiff case. For a complex stiff ODE system
+            in which f is not analytic, ZVODE is likely to have convergence
+            failures, and for this problem one should instead use DVODE on the
+            equivalent real system (in the real and imaginary parts of y).
+
+    "lsoda"
+
+        Real-valued Variable-coefficient Ordinary Differential Equation
+        solver, with fixed-leading-coefficient implementation. It provides
+        automatic method switching between implicit Adams method (for non-stiff
+        problems) and a method based on backward differentiation formulas (BDF)
+        (for stiff problems).
+
+        Source: http://www.netlib.org/odepack
+
+        .. warning::
+
+           This integrator is not re-entrant. You cannot have two `ode`
+           instances using the "lsoda" integrator at the same time.
+
+        This integrator accepts the following parameters in `set_integrator`
+        method of the `ode` class:
+
+        - atol : float or sequence
+          absolute tolerance for solution
+        - rtol : float or sequence
+          relative tolerance for solution
+        - lband : None or int
+        - uband : None or int
+          Jacobian band width, jac[i,j] != 0 for i-lband <= j <= i+uband.
+          Setting these requires your jac routine to return the jacobian
+          in packed format, jac_packed[i-j+uband, j] = jac[i,j].
+        - with_jacobian : bool
+          *Not used.*
+        - nsteps : int
+          Maximum number of (internally defined) steps allowed during one
+          call to the solver.
+        - first_step : float
+        - min_step : float
+        - max_step : float
+          Limits for the step sizes used by the integrator.
+        - max_order_ns : int
+          Maximum order used in the nonstiff case (default 12).
+        - max_order_s : int
+          Maximum order used in the stiff case (default 5).
+        - max_hnil : int
+          Maximum number of messages reporting too small step size (t + h = t)
+          (default 0)
+        - ixpr : int
+          Whether to generate extra printing at method switches (default False).
+
+    "dopri5"
+
+        This is an explicit runge-kutta method of order (4)5 due to Dormand &
+        Prince (with stepsize control and dense output).
+
+        Authors:
+
+            E. Hairer and G. Wanner
+            Universite de Geneve, Dept. de Mathematiques
+            CH-1211 Geneve 24, Switzerland
+            e-mail:  [email protected], [email protected]
+
+        This code is described in [HNW93]_.
+
+        This integrator accepts the following parameters in set_integrator()
+        method of the ode class:
+
+        - atol : float or sequence
+          absolute tolerance for solution
+        - rtol : float or sequence
+          relative tolerance for solution
+        - nsteps : int
+          Maximum number of (internally defined) steps allowed during one
+          call to the solver.
+        - first_step : float
+        - max_step : float
+        - safety : float
+          Safety factor on new step selection (default 0.9)
+        - ifactor : float
+        - dfactor : float
+          Maximum factor to increase/decrease step size by in one step
+        - beta : float
+          Beta parameter for stabilised step size control.
+        - verbosity : int
+          Switch for printing messages (< 0 for no messages).
+
+    "dop853"
+
+        This is an explicit runge-kutta method of order 8(5,3) due to Dormand
+        & Prince (with stepsize control and dense output).
+
+        Options and references the same as "dopri5".
+
+    Examples
+    --------
+
+    A problem to integrate and the corresponding jacobian:
+
+    >>> from scipy.integrate import ode
+    >>>
+    >>> y0, t0 = [1.0j, 2.0], 0
+    >>>
+    >>> def f(t, y, arg1):
+    ...     return [1j*arg1*y[0] + y[1], -arg1*y[1]**2]
+    >>> def jac(t, y, arg1):
+    ...     return [[1j*arg1, 1], [0, -arg1*2*y[1]]]
+
+    The integration:
+
+    >>> r = ode(f, jac).set_integrator('zvode', method='bdf')
+    >>> r.set_initial_value(y0, t0).set_f_params(2.0).set_jac_params(2.0)
+    >>> t1 = 10
+    >>> dt = 1
+    >>> while r.successful() and r.t < t1:
+    ...     print(r.t+dt, r.integrate(r.t+dt))
+    1 [-0.71038232+0.23749653j  0.40000271+0.j        ]
+    2.0 [0.19098503-0.52359246j 0.22222356+0.j        ]
+    3.0 [0.47153208+0.52701229j 0.15384681+0.j        ]
+    4.0 [-0.61905937+0.30726255j  0.11764744+0.j        ]
+    5.0 [0.02340997-0.61418799j 0.09523835+0.j        ]
+    6.0 [0.58643071+0.339819j 0.08000018+0.j      ]
+    7.0 [-0.52070105+0.44525141j  0.06896565+0.j        ]
+    8.0 [-0.15986733-0.61234476j  0.06060616+0.j        ]
+    9.0 [0.64850462+0.15048982j 0.05405414+0.j        ]
+    10.0 [-0.38404699+0.56382299j  0.04878055+0.j        ]
+
+    References
+    ----------
+    .. [HNW93] E. Hairer, S.P. Norsett and G. Wanner, Solving Ordinary
+        Differential Equations i. Nonstiff Problems. 2nd edition.
+        Springer Series in Computational Mathematics,
+        Springer-Verlag (1993)
+
+    """
+
+    def __init__(self, f, jac=None):
+        self.stiff = 0
+        self.f = f
+        self.jac = jac
+        self.f_params = ()
+        self.jac_params = ()
+        self._y = []
+
+    @property
+    def y(self):
+        return self._y
+
+    def set_initial_value(self, y, t=0.0):
+        """Set initial conditions y(t) = y."""
+        if isscalar(y):
+            y = [y]
+        n_prev = len(self._y)
+        if not n_prev:
+            self.set_integrator('')  # find first available integrator
+        self._y = asarray(y, self._integrator.scalar)
+        self.t = t
+        self._integrator.reset(len(self._y), self.jac is not None)
+        return self
+
+    def set_integrator(self, name, **integrator_params):
+        """
+        Set integrator by name.
+
+        Parameters
+        ----------
+        name : str
+            Name of the integrator.
+        **integrator_params
+            Additional parameters for the integrator.
+        """
+        integrator = find_integrator(name)
+        if integrator is None:
+            # FIXME: this really should be raise an exception. Will that break
+            # any code?
+            message = f'No integrator name match with {name!r} or is not available.'
+            warnings.warn(message, stacklevel=2)
+        else:
+            self._integrator = integrator(**integrator_params)
+            if not len(self._y):
+                self.t = 0.0
+                self._y = array([0.0], self._integrator.scalar)
+            self._integrator.reset(len(self._y), self.jac is not None)
+        return self
+
+    def integrate(self, t, step=False, relax=False):
+        """Find y=y(t), set y as an initial condition, and return y.
+
+        Parameters
+        ----------
+        t : float
+            The endpoint of the integration step.
+        step : bool
+            If True, and if the integrator supports the step method,
+            then perform a single integration step and return.
+            This parameter is provided in order to expose internals of
+            the implementation, and should not be changed from its default
+            value in most cases.
+        relax : bool
+            If True and if the integrator supports the run_relax method,
+            then integrate until t_1 >= t and return. ``relax`` is not
+            referenced if ``step=True``.
+            This parameter is provided in order to expose internals of
+            the implementation, and should not be changed from its default
+            value in most cases.
+
+        Returns
+        -------
+        y : float
+            The integrated value at t
+        """
+        if step and self._integrator.supports_step:
+            mth = self._integrator.step
+        elif relax and self._integrator.supports_run_relax:
+            mth = self._integrator.run_relax
+        else:
+            mth = self._integrator.run
+
+        try:
+            self._y, self.t = mth(self.f, self.jac or (lambda: None),
+                                  self._y, self.t, t,
+                                  self.f_params, self.jac_params)
+        except SystemError as e:
+            # f2py issue with tuple returns, see ticket 1187.
+            raise ValueError(
+                'Function to integrate must not return a tuple.'
+            ) from e
+
+        return self._y
+
+    def successful(self):
+        """Check if integration was successful."""
+        try:
+            self._integrator
+        except AttributeError:
+            self.set_integrator('')
+        return self._integrator.success == 1
+
+    def get_return_code(self):
+        """Extracts the return code for the integration to enable better control
+        if the integration fails.
+
+        In general, a return code > 0 implies success, while a return code < 0
+        implies failure.
+
+        Notes
+        -----
+        This section describes possible return codes and their meaning, for available
+        integrators that can be selected by `set_integrator` method.
+
+        "vode"
+
+        ===========  =======
+        Return Code  Message
+        ===========  =======
+        2            Integration successful.
+        -1           Excess work done on this call. (Perhaps wrong MF.)
+        -2           Excess accuracy requested. (Tolerances too small.)
+        -3           Illegal input detected. (See printed message.)
+        -4           Repeated error test failures. (Check all input.)
+        -5           Repeated convergence failures. (Perhaps bad Jacobian
+                     supplied or wrong choice of MF or tolerances.)
+        -6           Error weight became zero during problem. (Solution
+                     component i vanished, and ATOL or ATOL(i) = 0.)
+        ===========  =======
+
+        "zvode"
+
+        ===========  =======
+        Return Code  Message
+        ===========  =======
+        2            Integration successful.
+        -1           Excess work done on this call. (Perhaps wrong MF.)
+        -2           Excess accuracy requested. (Tolerances too small.)
+        -3           Illegal input detected. (See printed message.)
+        -4           Repeated error test failures. (Check all input.)
+        -5           Repeated convergence failures. (Perhaps bad Jacobian
+                     supplied or wrong choice of MF or tolerances.)
+        -6           Error weight became zero during problem. (Solution
+                     component i vanished, and ATOL or ATOL(i) = 0.)
+        ===========  =======
+
+        "dopri5"
+
+        ===========  =======
+        Return Code  Message
+        ===========  =======
+        1            Integration successful.
+        2            Integration successful (interrupted by solout).
+        -1           Input is not consistent.
+        -2           Larger nsteps is needed.
+        -3           Step size becomes too small.
+        -4           Problem is probably stiff (interrupted).
+        ===========  =======
+
+        "dop853"
+
+        ===========  =======
+        Return Code  Message
+        ===========  =======
+        1            Integration successful.
+        2            Integration successful (interrupted by solout).
+        -1           Input is not consistent.
+        -2           Larger nsteps is needed.
+        -3           Step size becomes too small.
+        -4           Problem is probably stiff (interrupted).
+        ===========  =======
+
+        "lsoda"
+
+        ===========  =======
+        Return Code  Message
+        ===========  =======
+        2            Integration successful.
+        -1           Excess work done on this call (perhaps wrong Dfun type).
+        -2           Excess accuracy requested (tolerances too small).
+        -3           Illegal input detected (internal error).
+        -4           Repeated error test failures (internal error).
+        -5           Repeated convergence failures (perhaps bad Jacobian or tolerances).
+        -6           Error weight became zero during problem.
+        -7           Internal workspace insufficient to finish (internal error).
+        ===========  =======
+        """
+        try:
+            self._integrator
+        except AttributeError:
+            self.set_integrator('')
+        return self._integrator.istate
+
+    def set_f_params(self, *args):
+        """Set extra parameters for user-supplied function f."""
+        self.f_params = args
+        return self
+
+    def set_jac_params(self, *args):
+        """Set extra parameters for user-supplied function jac."""
+        self.jac_params = args
+        return self
+
+    def set_solout(self, solout):
+        """
+        Set callable to be called at every successful integration step.
+
+        Parameters
+        ----------
+        solout : callable
+            ``solout(t, y)`` is called at each internal integrator step,
+            t is a scalar providing the current independent position
+            y is the current solution ``y.shape == (n,)``
+            solout should return -1 to stop integration
+            otherwise it should return None or 0
+
+        """
+        if self._integrator.supports_solout:
+            self._integrator.set_solout(solout)
+            if self._y is not None:
+                self._integrator.reset(len(self._y), self.jac is not None)
+        else:
+            raise ValueError("selected integrator does not support solout,"
+                             " choose another one")
+
+
+def _transform_banded_jac(bjac):
+    """
+    Convert a real matrix of the form (for example)
+
+        [0 0 A B]        [0 0 0 B]
+        [0 0 C D]        [0 0 A D]
+        [E F G H]   to   [0 F C H]
+        [I J K L]        [E J G L]
+                         [I 0 K 0]
+
+    That is, every other column is shifted up one.
+    """
+    # Shift every other column.
+    newjac = zeros((bjac.shape[0] + 1, bjac.shape[1]))
+    newjac[1:, ::2] = bjac[:, ::2]
+    newjac[:-1, 1::2] = bjac[:, 1::2]
+    return newjac
+
+
+class complex_ode(ode):
+    """
+    A wrapper of ode for complex systems.
+
+    This functions similarly as `ode`, but re-maps a complex-valued
+    equation system to a real-valued one before using the integrators.
+
+    Parameters
+    ----------
+    f : callable ``f(t, y, *f_args)``
+        Rhs of the equation. t is a scalar, ``y.shape == (n,)``.
+        ``f_args`` is set by calling ``set_f_params(*args)``.
+    jac : callable ``jac(t, y, *jac_args)``
+        Jacobian of the rhs, ``jac[i,j] = d f[i] / d y[j]``.
+        ``jac_args`` is set by calling ``set_f_params(*args)``.
+
+    Attributes
+    ----------
+    t : float
+        Current time.
+    y : ndarray
+        Current variable values.
+
+    Examples
+    --------
+    For usage examples, see `ode`.
+
+    """
+
+    def __init__(self, f, jac=None):
+        self.cf = f
+        self.cjac = jac
+        if jac is None:
+            ode.__init__(self, self._wrap, None)
+        else:
+            ode.__init__(self, self._wrap, self._wrap_jac)
+
+    def _wrap(self, t, y, *f_args):
+        f = self.cf(*((t, y[::2] + 1j * y[1::2]) + f_args))
+        # self.tmp is a real-valued array containing the interleaved
+        # real and imaginary parts of f.
+        self.tmp[::2] = real(f)
+        self.tmp[1::2] = imag(f)
+        return self.tmp
+
+    def _wrap_jac(self, t, y, *jac_args):
+        # jac is the complex Jacobian computed by the user-defined function.
+        jac = self.cjac(*((t, y[::2] + 1j * y[1::2]) + jac_args))
+
+        # jac_tmp is the real version of the complex Jacobian.  Each complex
+        # entry in jac, say 2+3j, becomes a 2x2 block of the form
+        #     [2 -3]
+        #     [3  2]
+        jac_tmp = zeros((2 * jac.shape[0], 2 * jac.shape[1]))
+        jac_tmp[1::2, 1::2] = jac_tmp[::2, ::2] = real(jac)
+        jac_tmp[1::2, ::2] = imag(jac)
+        jac_tmp[::2, 1::2] = -jac_tmp[1::2, ::2]
+
+        ml = getattr(self._integrator, 'ml', None)
+        mu = getattr(self._integrator, 'mu', None)
+        if ml is not None or mu is not None:
+            # Jacobian is banded.  The user's Jacobian function has computed
+            # the complex Jacobian in packed format.  The corresponding
+            # real-valued version has every other column shifted up.
+            jac_tmp = _transform_banded_jac(jac_tmp)
+
+        return jac_tmp
+
+    @property
+    def y(self):
+        return self._y[::2] + 1j * self._y[1::2]
+
+    def set_integrator(self, name, **integrator_params):
+        """
+        Set integrator by name.
+
+        Parameters
+        ----------
+        name : str
+            Name of the integrator
+        **integrator_params
+            Additional parameters for the integrator.
+        """
+        if name == 'zvode':
+            raise ValueError("zvode must be used with ode, not complex_ode")
+
+        lband = integrator_params.get('lband')
+        uband = integrator_params.get('uband')
+        if lband is not None or uband is not None:
+            # The Jacobian is banded.  Override the user-supplied bandwidths
+            # (which are for the complex Jacobian) with the bandwidths of
+            # the corresponding real-valued Jacobian wrapper of the complex
+            # Jacobian.
+            integrator_params['lband'] = 2 * (lband or 0) + 1
+            integrator_params['uband'] = 2 * (uband or 0) + 1
+
+        return ode.set_integrator(self, name, **integrator_params)
+
+    def set_initial_value(self, y, t=0.0):
+        """Set initial conditions y(t) = y."""
+        y = asarray(y)
+        self.tmp = zeros(y.size * 2, 'float')
+        self.tmp[::2] = real(y)
+        self.tmp[1::2] = imag(y)
+        return ode.set_initial_value(self, self.tmp, t)
+
+    def integrate(self, t, step=False, relax=False):
+        """Find y=y(t), set y as an initial condition, and return y.
+
+        Parameters
+        ----------
+        t : float
+            The endpoint of the integration step.
+        step : bool
+            If True, and if the integrator supports the step method,
+            then perform a single integration step and return.
+            This parameter is provided in order to expose internals of
+            the implementation, and should not be changed from its default
+            value in most cases.
+        relax : bool
+            If True and if the integrator supports the run_relax method,
+            then integrate until t_1 >= t and return. ``relax`` is not
+            referenced if ``step=True``.
+            This parameter is provided in order to expose internals of
+            the implementation, and should not be changed from its default
+            value in most cases.
+
+        Returns
+        -------
+        y : float
+            The integrated value at t
+        """
+        y = ode.integrate(self, t, step, relax)
+        return y[::2] + 1j * y[1::2]
+
+    def set_solout(self, solout):
+        """
+        Set callable to be called at every successful integration step.
+
+        Parameters
+        ----------
+        solout : callable
+            ``solout(t, y)`` is called at each internal integrator step,
+            t is a scalar providing the current independent position
+            y is the current solution ``y.shape == (n,)``
+            solout should return -1 to stop integration
+            otherwise it should return None or 0
+
+        """
+        if self._integrator.supports_solout:
+            self._integrator.set_solout(solout, complex=True)
+        else:
+            raise TypeError("selected integrator does not support solouta,"
+                            + "choose another one")
+
+
+# ------------------------------------------------------------------------------
+# ODE integrators
+# ------------------------------------------------------------------------------
+
+def find_integrator(name):
+    for cl in IntegratorBase.integrator_classes:
+        if re.match(name, cl.__name__, re.I):
+            return cl
+    return None
+
+
+class IntegratorConcurrencyError(RuntimeError):
+    """
+    Failure due to concurrent usage of an integrator that can be used
+    only for a single problem at a time.
+
+    """
+
+    def __init__(self, name):
+        msg = ("Integrator `%s` can be used to solve only a single problem "
+               "at a time. If you want to integrate multiple problems, "
+               "consider using a different integrator "
+               "(see `ode.set_integrator`)") % name
+        RuntimeError.__init__(self, msg)
+
+
+class IntegratorBase:
+    runner = None  # runner is None => integrator is not available
+    success = None  # success==1 if integrator was called successfully
+    istate = None  # istate > 0 means success, istate < 0 means failure
+    supports_run_relax = None
+    supports_step = None
+    supports_solout = False
+    integrator_classes = []
+    scalar = float
+
+    def acquire_new_handle(self):
+        # Some of the integrators have internal state (ancient
+        # Fortran...), and so only one instance can use them at a time.
+        # We keep track of this, and fail when concurrent usage is tried.
+        self.__class__.active_global_handle += 1
+        self.handle = self.__class__.active_global_handle
+
+    def check_handle(self):
+        if self.handle is not self.__class__.active_global_handle:
+            raise IntegratorConcurrencyError(self.__class__.__name__)
+
+    def reset(self, n, has_jac):
+        """Prepare integrator for call: allocate memory, set flags, etc.
+        n - number of equations.
+        has_jac - if user has supplied function for evaluating Jacobian.
+        """
+
+    def run(self, f, jac, y0, t0, t1, f_params, jac_params):
+        """Integrate from t=t0 to t=t1 using y0 as an initial condition.
+        Return 2-tuple (y1,t1) where y1 is the result and t=t1
+        defines the stoppage coordinate of the result.
+        """
+        raise NotImplementedError('all integrators must define '
+                                  'run(f, jac, t0, t1, y0, f_params, jac_params)')
+
+    def step(self, f, jac, y0, t0, t1, f_params, jac_params):
+        """Make one integration step and return (y1,t1)."""
+        raise NotImplementedError('%s does not support step() method' %
+                                  self.__class__.__name__)
+
+    def run_relax(self, f, jac, y0, t0, t1, f_params, jac_params):
+        """Integrate from t=t0 to t>=t1 and return (y1,t)."""
+        raise NotImplementedError('%s does not support run_relax() method' %
+                                  self.__class__.__name__)
+
+    # XXX: __str__ method for getting visual state of the integrator
+
+
+def _vode_banded_jac_wrapper(jacfunc, ml, jac_params):
+    """
+    Wrap a banded Jacobian function with a function that pads
+    the Jacobian with `ml` rows of zeros.
+    """
+
+    def jac_wrapper(t, y):
+        jac = asarray(jacfunc(t, y, *jac_params))
+        padded_jac = vstack((jac, zeros((ml, jac.shape[1]))))
+        return padded_jac
+
+    return jac_wrapper
+
+
+class vode(IntegratorBase):
+    runner = getattr(_vode, 'dvode', None)
+
+    messages = {-1: 'Excess work done on this call. (Perhaps wrong MF.)',
+                -2: 'Excess accuracy requested. (Tolerances too small.)',
+                -3: 'Illegal input detected. (See printed message.)',
+                -4: 'Repeated error test failures. (Check all input.)',
+                -5: 'Repeated convergence failures. (Perhaps bad'
+                    ' Jacobian supplied or wrong choice of MF or tolerances.)',
+                -6: 'Error weight became zero during problem. (Solution'
+                    ' component i vanished, and ATOL or ATOL(i) = 0.)'
+                }
+    supports_run_relax = 1
+    supports_step = 1
+    active_global_handle = 0
+
+    def __init__(self,
+                 method='adams',
+                 with_jacobian=False,
+                 rtol=1e-6, atol=1e-12,
+                 lband=None, uband=None,
+                 order=12,
+                 nsteps=500,
+                 max_step=0.0,  # corresponds to infinite
+                 min_step=0.0,
+                 first_step=0.0,  # determined by solver
+                 ):
+
+        if re.match(method, r'adams', re.I):
+            self.meth = 1
+        elif re.match(method, r'bdf', re.I):
+            self.meth = 2
+        else:
+            raise ValueError('Unknown integration method %s' % method)
+        self.with_jacobian = with_jacobian
+        self.rtol = rtol
+        self.atol = atol
+        self.mu = uband
+        self.ml = lband
+
+        self.order = order
+        self.nsteps = nsteps
+        self.max_step = max_step
+        self.min_step = min_step
+        self.first_step = first_step
+        self.success = 1
+
+        self.initialized = False
+
+    def _determine_mf_and_set_bands(self, has_jac):
+        """
+        Determine the `MF` parameter (Method Flag) for the Fortran subroutine `dvode`.
+
+        In the Fortran code, the legal values of `MF` are:
+            10, 11, 12, 13, 14, 15, 20, 21, 22, 23, 24, 25,
+            -11, -12, -14, -15, -21, -22, -24, -25
+        but this Python wrapper does not use negative values.
+
+        Returns
+
+            mf  = 10*self.meth + miter
+
+        self.meth is the linear multistep method:
+            self.meth == 1:  method="adams"
+            self.meth == 2:  method="bdf"
+
+        miter is the correction iteration method:
+            miter == 0:  Functional iteration; no Jacobian involved.
+            miter == 1:  Chord iteration with user-supplied full Jacobian.
+            miter == 2:  Chord iteration with internally computed full Jacobian.
+            miter == 3:  Chord iteration with internally computed diagonal Jacobian.
+            miter == 4:  Chord iteration with user-supplied banded Jacobian.
+            miter == 5:  Chord iteration with internally computed banded Jacobian.
+
+        Side effects: If either self.mu or self.ml is not None and the other is None,
+        then the one that is None is set to 0.
+        """
+
+        jac_is_banded = self.mu is not None or self.ml is not None
+        if jac_is_banded:
+            if self.mu is None:
+                self.mu = 0
+            if self.ml is None:
+                self.ml = 0
+
+        # has_jac is True if the user provided a Jacobian function.
+        if has_jac:
+            if jac_is_banded:
+                miter = 4
+            else:
+                miter = 1
+        else:
+            if jac_is_banded:
+                if self.ml == self.mu == 0:
+                    miter = 3  # Chord iteration with internal diagonal Jacobian.
+                else:
+                    miter = 5  # Chord iteration with internal banded Jacobian.
+            else:
+                # self.with_jacobian is set by the user in
+                # the call to ode.set_integrator.
+                if self.with_jacobian:
+                    miter = 2  # Chord iteration with internal full Jacobian.
+                else:
+                    miter = 0  # Functional iteration; no Jacobian involved.
+
+        mf = 10 * self.meth + miter
+        return mf
+
+    def reset(self, n, has_jac):
+        mf = self._determine_mf_and_set_bands(has_jac)
+
+        if mf == 10:
+            lrw = 20 + 16 * n
+        elif mf in [11, 12]:
+            lrw = 22 + 16 * n + 2 * n * n
+        elif mf == 13:
+            lrw = 22 + 17 * n
+        elif mf in [14, 15]:
+            lrw = 22 + 18 * n + (3 * self.ml + 2 * self.mu) * n
+        elif mf == 20:
+            lrw = 20 + 9 * n
+        elif mf in [21, 22]:
+            lrw = 22 + 9 * n + 2 * n * n
+        elif mf == 23:
+            lrw = 22 + 10 * n
+        elif mf in [24, 25]:
+            lrw = 22 + 11 * n + (3 * self.ml + 2 * self.mu) * n
+        else:
+            raise ValueError('Unexpected mf=%s' % mf)
+
+        if mf % 10 in [0, 3]:
+            liw = 30
+        else:
+            liw = 30 + n
+
+        rwork = zeros((lrw,), float)
+        rwork[4] = self.first_step
+        rwork[5] = self.max_step
+        rwork[6] = self.min_step
+        self.rwork = rwork
+
+        iwork = zeros((liw,), _vode_int_dtype)
+        if self.ml is not None:
+            iwork[0] = self.ml
+        if self.mu is not None:
+            iwork[1] = self.mu
+        iwork[4] = self.order
+        iwork[5] = self.nsteps
+        iwork[6] = 2  # mxhnil
+        self.iwork = iwork
+
+        self.call_args = [self.rtol, self.atol, 1, 1,
+                          self.rwork, self.iwork, mf]
+        self.success = 1
+        self.initialized = False
+
+    def run(self, f, jac, y0, t0, t1, f_params, jac_params):
+        if self.initialized:
+            self.check_handle()
+        else:
+            self.initialized = True
+            self.acquire_new_handle()
+
+        if self.ml is not None and self.ml > 0:
+            # Banded Jacobian. Wrap the user-provided function with one
+            # that pads the Jacobian array with the extra `self.ml` rows
+            # required by the f2py-generated wrapper.
+            jac = _vode_banded_jac_wrapper(jac, self.ml, jac_params)
+
+        args = ((f, jac, y0, t0, t1) + tuple(self.call_args) +
+                (f_params, jac_params))
+        y1, t, istate = self.runner(*args)
+        self.istate = istate
+        if istate < 0:
+            unexpected_istate_msg = f'Unexpected istate={istate:d}'
+            warnings.warn('{:s}: {:s}'.format(self.__class__.__name__,
+                          self.messages.get(istate, unexpected_istate_msg)),
+                          stacklevel=2)
+            self.success = 0
+        else:
+            self.call_args[3] = 2  # upgrade istate from 1 to 2
+            self.istate = 2
+        return y1, t
+
+    def step(self, *args):
+        itask = self.call_args[2]
+        self.call_args[2] = 2
+        r = self.run(*args)
+        self.call_args[2] = itask
+        return r
+
+    def run_relax(self, *args):
+        itask = self.call_args[2]
+        self.call_args[2] = 3
+        r = self.run(*args)
+        self.call_args[2] = itask
+        return r
+
+
+if vode.runner is not None:
+    IntegratorBase.integrator_classes.append(vode)
+
+
+class zvode(vode):
+    runner = getattr(_vode, 'zvode', None)
+
+    supports_run_relax = 1
+    supports_step = 1
+    scalar = complex
+    active_global_handle = 0
+
+    def reset(self, n, has_jac):
+        mf = self._determine_mf_and_set_bands(has_jac)
+
+        if mf in (10,):
+            lzw = 15 * n
+        elif mf in (11, 12):
+            lzw = 15 * n + 2 * n ** 2
+        elif mf in (-11, -12):
+            lzw = 15 * n + n ** 2
+        elif mf in (13,):
+            lzw = 16 * n
+        elif mf in (14, 15):
+            lzw = 17 * n + (3 * self.ml + 2 * self.mu) * n
+        elif mf in (-14, -15):
+            lzw = 16 * n + (2 * self.ml + self.mu) * n
+        elif mf in (20,):
+            lzw = 8 * n
+        elif mf in (21, 22):
+            lzw = 8 * n + 2 * n ** 2
+        elif mf in (-21, -22):
+            lzw = 8 * n + n ** 2
+        elif mf in (23,):
+            lzw = 9 * n
+        elif mf in (24, 25):
+            lzw = 10 * n + (3 * self.ml + 2 * self.mu) * n
+        elif mf in (-24, -25):
+            lzw = 9 * n + (2 * self.ml + self.mu) * n
+
+        lrw = 20 + n
+
+        if mf % 10 in (0, 3):
+            liw = 30
+        else:
+            liw = 30 + n
+
+        zwork = zeros((lzw,), complex)
+        self.zwork = zwork
+
+        rwork = zeros((lrw,), float)
+        rwork[4] = self.first_step
+        rwork[5] = self.max_step
+        rwork[6] = self.min_step
+        self.rwork = rwork
+
+        iwork = zeros((liw,), _vode_int_dtype)
+        if self.ml is not None:
+            iwork[0] = self.ml
+        if self.mu is not None:
+            iwork[1] = self.mu
+        iwork[4] = self.order
+        iwork[5] = self.nsteps
+        iwork[6] = 2  # mxhnil
+        self.iwork = iwork
+
+        self.call_args = [self.rtol, self.atol, 1, 1,
+                          self.zwork, self.rwork, self.iwork, mf]
+        self.success = 1
+        self.initialized = False
+
+
+if zvode.runner is not None:
+    IntegratorBase.integrator_classes.append(zvode)
+
+
+class dopri5(IntegratorBase):
+    runner = getattr(_dop, 'dopri5', None)
+    name = 'dopri5'
+    supports_solout = True
+
+    messages = {1: 'computation successful',
+                2: 'computation successful (interrupted by solout)',
+                -1: 'input is not consistent',
+                -2: 'larger nsteps is needed',
+                -3: 'step size becomes too small',
+                -4: 'problem is probably stiff (interrupted)',
+                }
+
+    def __init__(self,
+                 rtol=1e-6, atol=1e-12,
+                 nsteps=500,
+                 max_step=0.0,
+                 first_step=0.0,  # determined by solver
+                 safety=0.9,
+                 ifactor=10.0,
+                 dfactor=0.2,
+                 beta=0.0,
+                 method=None,
+                 verbosity=-1,  # no messages if negative
+                 ):
+        self.rtol = rtol
+        self.atol = atol
+        self.nsteps = nsteps
+        self.max_step = max_step
+        self.first_step = first_step
+        self.safety = safety
+        self.ifactor = ifactor
+        self.dfactor = dfactor
+        self.beta = beta
+        self.verbosity = verbosity
+        self.success = 1
+        self.set_solout(None)
+
+    def set_solout(self, solout, complex=False):
+        self.solout = solout
+        self.solout_cmplx = complex
+        if solout is None:
+            self.iout = 0
+        else:
+            self.iout = 1
+
+    def reset(self, n, has_jac):
+        work = zeros((8 * n + 21,), float)
+        work[1] = self.safety
+        work[2] = self.dfactor
+        work[3] = self.ifactor
+        work[4] = self.beta
+        work[5] = self.max_step
+        work[6] = self.first_step
+        self.work = work
+        iwork = zeros((21,), _dop_int_dtype)
+        iwork[0] = self.nsteps
+        iwork[2] = self.verbosity
+        self.iwork = iwork
+        self.call_args = [self.rtol, self.atol, self._solout,
+                          self.iout, self.work, self.iwork]
+        self.success = 1
+
+    def run(self, f, jac, y0, t0, t1, f_params, jac_params):
+        x, y, iwork, istate = self.runner(*((f, t0, y0, t1) +
+                                          tuple(self.call_args) + (f_params,)))
+        self.istate = istate
+        if istate < 0:
+            unexpected_istate_msg = f'Unexpected istate={istate:d}'
+            warnings.warn('{:s}: {:s}'.format(self.__class__.__name__,
+                          self.messages.get(istate, unexpected_istate_msg)),
+                          stacklevel=2)
+            self.success = 0
+        return y, x
+
+    def _solout(self, nr, xold, x, y, nd, icomp, con):
+        if self.solout is not None:
+            if self.solout_cmplx:
+                y = y[::2] + 1j * y[1::2]
+            return self.solout(x, y)
+        else:
+            return 1
+
+
+if dopri5.runner is not None:
+    IntegratorBase.integrator_classes.append(dopri5)
+
+
+class dop853(dopri5):
+    runner = getattr(_dop, 'dop853', None)
+    name = 'dop853'
+
+    def __init__(self,
+                 rtol=1e-6, atol=1e-12,
+                 nsteps=500,
+                 max_step=0.0,
+                 first_step=0.0,  # determined by solver
+                 safety=0.9,
+                 ifactor=6.0,
+                 dfactor=0.3,
+                 beta=0.0,
+                 method=None,
+                 verbosity=-1,  # no messages if negative
+                 ):
+        super().__init__(rtol, atol, nsteps, max_step, first_step, safety,
+                         ifactor, dfactor, beta, method, verbosity)
+
+    def reset(self, n, has_jac):
+        work = zeros((11 * n + 21,), float)
+        work[1] = self.safety
+        work[2] = self.dfactor
+        work[3] = self.ifactor
+        work[4] = self.beta
+        work[5] = self.max_step
+        work[6] = self.first_step
+        self.work = work
+        iwork = zeros((21,), _dop_int_dtype)
+        iwork[0] = self.nsteps
+        iwork[2] = self.verbosity
+        self.iwork = iwork
+        self.call_args = [self.rtol, self.atol, self._solout,
+                          self.iout, self.work, self.iwork]
+        self.success = 1
+
+
+if dop853.runner is not None:
+    IntegratorBase.integrator_classes.append(dop853)
+
+
+class lsoda(IntegratorBase):
+    runner = getattr(_lsoda, 'lsoda', None)
+    active_global_handle = 0
+
+    messages = {
+        2: "Integration successful.",
+        -1: "Excess work done on this call (perhaps wrong Dfun type).",
+        -2: "Excess accuracy requested (tolerances too small).",
+        -3: "Illegal input detected (internal error).",
+        -4: "Repeated error test failures (internal error).",
+        -5: "Repeated convergence failures (perhaps bad Jacobian or tolerances).",
+        -6: "Error weight became zero during problem.",
+        -7: "Internal workspace insufficient to finish (internal error)."
+    }
+
+    def __init__(self,
+                 with_jacobian=False,
+                 rtol=1e-6, atol=1e-12,
+                 lband=None, uband=None,
+                 nsteps=500,
+                 max_step=0.0,  # corresponds to infinite
+                 min_step=0.0,
+                 first_step=0.0,  # determined by solver
+                 ixpr=0,
+                 max_hnil=0,
+                 max_order_ns=12,
+                 max_order_s=5,
+                 method=None
+                 ):
+
+        self.with_jacobian = with_jacobian
+        self.rtol = rtol
+        self.atol = atol
+        self.mu = uband
+        self.ml = lband
+
+        self.max_order_ns = max_order_ns
+        self.max_order_s = max_order_s
+        self.nsteps = nsteps
+        self.max_step = max_step
+        self.min_step = min_step
+        self.first_step = first_step
+        self.ixpr = ixpr
+        self.max_hnil = max_hnil
+        self.success = 1
+
+        self.initialized = False
+
+    def reset(self, n, has_jac):
+        # Calculate parameters for Fortran subroutine dvode.
+        if has_jac:
+            if self.mu is None and self.ml is None:
+                jt = 1
+            else:
+                if self.mu is None:
+                    self.mu = 0
+                if self.ml is None:
+                    self.ml = 0
+                jt = 4
+        else:
+            if self.mu is None and self.ml is None:
+                jt = 2
+            else:
+                if self.mu is None:
+                    self.mu = 0
+                if self.ml is None:
+                    self.ml = 0
+                jt = 5
+        lrn = 20 + (self.max_order_ns + 4) * n
+        if jt in [1, 2]:
+            lrs = 22 + (self.max_order_s + 4) * n + n * n
+        elif jt in [4, 5]:
+            lrs = 22 + (self.max_order_s + 5 + 2 * self.ml + self.mu) * n
+        else:
+            raise ValueError('Unexpected jt=%s' % jt)
+        lrw = max(lrn, lrs)
+        liw = 20 + n
+        rwork = zeros((lrw,), float)
+        rwork[4] = self.first_step
+        rwork[5] = self.max_step
+        rwork[6] = self.min_step
+        self.rwork = rwork
+        iwork = zeros((liw,), _lsoda_int_dtype)
+        if self.ml is not None:
+            iwork[0] = self.ml
+        if self.mu is not None:
+            iwork[1] = self.mu
+        iwork[4] = self.ixpr
+        iwork[5] = self.nsteps
+        iwork[6] = self.max_hnil
+        iwork[7] = self.max_order_ns
+        iwork[8] = self.max_order_s
+        self.iwork = iwork
+        self.call_args = [self.rtol, self.atol, 1, 1,
+                          self.rwork, self.iwork, jt]
+        self.success = 1
+        self.initialized = False
+
+    def run(self, f, jac, y0, t0, t1, f_params, jac_params):
+        if self.initialized:
+            self.check_handle()
+        else:
+            self.initialized = True
+            self.acquire_new_handle()
+        args = [f, y0, t0, t1] + self.call_args[:-1] + \
+               [jac, self.call_args[-1], f_params, 0, jac_params]
+        y1, t, istate = self.runner(*args)
+        self.istate = istate
+        if istate < 0:
+            unexpected_istate_msg = f'Unexpected istate={istate:d}'
+            warnings.warn('{:s}: {:s}'.format(self.__class__.__name__,
+                          self.messages.get(istate, unexpected_istate_msg)),
+                          stacklevel=2)
+            self.success = 0
+        else:
+            self.call_args[3] = 2  # upgrade istate from 1 to 2
+            self.istate = 2
+        return y1, t
+
+    def step(self, *args):
+        itask = self.call_args[2]
+        self.call_args[2] = 2
+        r = self.run(*args)
+        self.call_args[2] = itask
+        return r
+
+    def run_relax(self, *args):
+        itask = self.call_args[2]
+        self.call_args[2] = 3
+        r = self.run(*args)
+        self.call_args[2] = itask
+        return r
+
+
+if lsoda.runner:
+    IntegratorBase.integrator_classes.append(lsoda)

llmeval-env/lib/python3.10/site-packages/scipy/integrate/_odepack_py.py

@@ -0,0 +1,262 @@
+# Author: Travis Oliphant
+
+__all__ = ['odeint', 'ODEintWarning']
+
+import numpy as np
+from . import _odepack
+from copy import copy
+import warnings
+
+
+class ODEintWarning(Warning):
+    """Warning raised during the execution of `odeint`."""
+    pass
+
+
+_msgs = {2: "Integration successful.",
+         1: "Nothing was done; the integration time was 0.",
+         -1: "Excess work done on this call (perhaps wrong Dfun type).",
+         -2: "Excess accuracy requested (tolerances too small).",
+         -3: "Illegal input detected (internal error).",
+         -4: "Repeated error test failures (internal error).",
+         -5: "Repeated convergence failures (perhaps bad Jacobian or tolerances).",
+         -6: "Error weight became zero during problem.",
+         -7: "Internal workspace insufficient to finish (internal error).",
+         -8: "Run terminated (internal error)."
+         }
+
+
+def odeint(func, y0, t, args=(), Dfun=None, col_deriv=0, full_output=0,
+           ml=None, mu=None, rtol=None, atol=None, tcrit=None, h0=0.0,
+           hmax=0.0, hmin=0.0, ixpr=0, mxstep=0, mxhnil=0, mxordn=12,
+           mxords=5, printmessg=0, tfirst=False):
+    """
+    Integrate a system of ordinary differential equations.
+
+    .. note:: For new code, use `scipy.integrate.solve_ivp` to solve a
+              differential equation.
+
+    Solve a system of ordinary differential equations using lsoda from the
+    FORTRAN library odepack.
+
+    Solves the initial value problem for stiff or non-stiff systems
+    of first order ode-s::
+
+        dy/dt = func(y, t, ...)  [or func(t, y, ...)]
+
+    where y can be a vector.
+
+    .. note:: By default, the required order of the first two arguments of
+              `func` are in the opposite order of the arguments in the system
+              definition function used by the `scipy.integrate.ode` class and
+              the function `scipy.integrate.solve_ivp`. To use a function with
+              the signature ``func(t, y, ...)``, the argument `tfirst` must be
+              set to ``True``.
+
+    Parameters
+    ----------
+    func : callable(y, t, ...) or callable(t, y, ...)
+        Computes the derivative of y at t.
+        If the signature is ``callable(t, y, ...)``, then the argument
+        `tfirst` must be set ``True``.
+    y0 : array
+        Initial condition on y (can be a vector).
+    t : array
+        A sequence of time points for which to solve for y. The initial
+        value point should be the first element of this sequence.
+        This sequence must be monotonically increasing or monotonically
+        decreasing; repeated values are allowed.
+    args : tuple, optional
+        Extra arguments to pass to function.
+    Dfun : callable(y, t, ...) or callable(t, y, ...)
+        Gradient (Jacobian) of `func`.
+        If the signature is ``callable(t, y, ...)``, then the argument
+        `tfirst` must be set ``True``.
+    col_deriv : bool, optional
+        True if `Dfun` defines derivatives down columns (faster),
+        otherwise `Dfun` should define derivatives across rows.
+    full_output : bool, optional
+        True if to return a dictionary of optional outputs as the second output
+    printmessg : bool, optional
+        Whether to print the convergence message
+    tfirst : bool, optional
+        If True, the first two arguments of `func` (and `Dfun`, if given)
+        must ``t, y`` instead of the default ``y, t``.
+
+        .. versionadded:: 1.1.0
+
+    Returns
+    -------
+    y : array, shape (len(t), len(y0))
+        Array containing the value of y for each desired time in t,
+        with the initial value `y0` in the first row.
+    infodict : dict, only returned if full_output == True
+        Dictionary containing additional output information
+
+        =======  ============================================================
+        key      meaning
+        =======  ============================================================
+        'hu'     vector of step sizes successfully used for each time step
+        'tcur'   vector with the value of t reached for each time step
+                 (will always be at least as large as the input times)
+        'tolsf'  vector of tolerance scale factors, greater than 1.0,
+                 computed when a request for too much accuracy was detected
+        'tsw'    value of t at the time of the last method switch
+                 (given for each time step)
+        'nst'    cumulative number of time steps
+        'nfe'    cumulative number of function evaluations for each time step
+        'nje'    cumulative number of jacobian evaluations for each time step
+        'nqu'    a vector of method orders for each successful step
+        'imxer'  index of the component of largest magnitude in the
+                 weighted local error vector (e / ewt) on an error return, -1
+                 otherwise
+        'lenrw'  the length of the double work array required
+        'leniw'  the length of integer work array required
+        'mused'  a vector of method indicators for each successful time step:
+                 1: adams (nonstiff), 2: bdf (stiff)
+        =======  ============================================================
+
+    Other Parameters
+    ----------------
+    ml, mu : int, optional
+        If either of these are not None or non-negative, then the
+        Jacobian is assumed to be banded. These give the number of
+        lower and upper non-zero diagonals in this banded matrix.
+        For the banded case, `Dfun` should return a matrix whose
+        rows contain the non-zero bands (starting with the lowest diagonal).
+        Thus, the return matrix `jac` from `Dfun` should have shape
+        ``(ml + mu + 1, len(y0))`` when ``ml >=0`` or ``mu >=0``.
+        The data in `jac` must be stored such that ``jac[i - j + mu, j]``
+        holds the derivative of the ``i``\\ th equation with respect to the
+        ``j``\\ th state variable.  If `col_deriv` is True, the transpose of
+        this `jac` must be returned.
+    rtol, atol : float, optional
+        The input parameters `rtol` and `atol` determine the error
+        control performed by the solver.  The solver will control the
+        vector, e, of estimated local errors in y, according to an
+        inequality of the form ``max-norm of (e / ewt) <= 1``,
+        where ewt is a vector of positive error weights computed as
+        ``ewt = rtol * abs(y) + atol``.
+        rtol and atol can be either vectors the same length as y or scalars.
+        Defaults to 1.49012e-8.
+    tcrit : ndarray, optional
+        Vector of critical points (e.g., singularities) where integration
+        care should be taken.
+    h0 : float, (0: solver-determined), optional
+        The step size to be attempted on the first step.
+    hmax : float, (0: solver-determined), optional
+        The maximum absolute step size allowed.
+    hmin : float, (0: solver-determined), optional
+        The minimum absolute step size allowed.
+    ixpr : bool, optional
+        Whether to generate extra printing at method switches.
+    mxstep : int, (0: solver-determined), optional
+        Maximum number of (internally defined) steps allowed for each
+        integration point in t.
+    mxhnil : int, (0: solver-determined), optional
+        Maximum number of messages printed.
+    mxordn : int, (0: solver-determined), optional
+        Maximum order to be allowed for the non-stiff (Adams) method.
+    mxords : int, (0: solver-determined), optional
+        Maximum order to be allowed for the stiff (BDF) method.
+
+    See Also
+    --------
+    solve_ivp : solve an initial value problem for a system of ODEs
+    ode : a more object-oriented integrator based on VODE
+    quad : for finding the area under a curve
+
+    Examples
+    --------
+    The second order differential equation for the angle `theta` of a
+    pendulum acted on by gravity with friction can be written::
+
+        theta''(t) + b*theta'(t) + c*sin(theta(t)) = 0
+
+    where `b` and `c` are positive constants, and a prime (') denotes a
+    derivative. To solve this equation with `odeint`, we must first convert
+    it to a system of first order equations. By defining the angular
+    velocity ``omega(t) = theta'(t)``, we obtain the system::
+
+        theta'(t) = omega(t)
+        omega'(t) = -b*omega(t) - c*sin(theta(t))
+
+    Let `y` be the vector [`theta`, `omega`]. We implement this system
+    in Python as:
+
+    >>> import numpy as np
+    >>> def pend(y, t, b, c):
+    ...     theta, omega = y
+    ...     dydt = [omega, -b*omega - c*np.sin(theta)]
+    ...     return dydt
+    ...
+
+    We assume the constants are `b` = 0.25 and `c` = 5.0:
+
+    >>> b = 0.25
+    >>> c = 5.0
+
+    For initial conditions, we assume the pendulum is nearly vertical
+    with `theta(0)` = `pi` - 0.1, and is initially at rest, so
+    `omega(0)` = 0.  Then the vector of initial conditions is
+
+    >>> y0 = [np.pi - 0.1, 0.0]
+
+    We will generate a solution at 101 evenly spaced samples in the interval
+    0 <= `t` <= 10.  So our array of times is:
+
+    >>> t = np.linspace(0, 10, 101)
+
+    Call `odeint` to generate the solution. To pass the parameters
+    `b` and `c` to `pend`, we give them to `odeint` using the `args`
+    argument.
+
+    >>> from scipy.integrate import odeint
+    >>> sol = odeint(pend, y0, t, args=(b, c))
+
+    The solution is an array with shape (101, 2). The first column
+    is `theta(t)`, and the second is `omega(t)`. The following code
+    plots both components.
+
+    >>> import matplotlib.pyplot as plt
+    >>> plt.plot(t, sol[:, 0], 'b', label='theta(t)')
+    >>> plt.plot(t, sol[:, 1], 'g', label='omega(t)')
+    >>> plt.legend(loc='best')
+    >>> plt.xlabel('t')
+    >>> plt.grid()
+    >>> plt.show()
+    """
+
+    if ml is None:
+        ml = -1  # changed to zero inside function call
+    if mu is None:
+        mu = -1  # changed to zero inside function call
+
+    dt = np.diff(t)
+    if not ((dt >= 0).all() or (dt <= 0).all()):
+        raise ValueError("The values in t must be monotonically increasing "
+                         "or monotonically decreasing; repeated values are "
+                         "allowed.")
+
+    t = copy(t)
+    y0 = copy(y0)
+    output = _odepack.odeint(func, y0, t, args, Dfun, col_deriv, ml, mu,
+                             full_output, rtol, atol, tcrit, h0, hmax, hmin,
+                             ixpr, mxstep, mxhnil, mxordn, mxords,
+                             int(bool(tfirst)))
+    if output[-1] < 0:
+        warning_msg = (f"{_msgs[output[-1]]} Run with full_output = 1 to "
+                       f"get quantitative information.")
+        warnings.warn(warning_msg, ODEintWarning, stacklevel=2)
+    elif printmessg:
+        warning_msg = _msgs[output[-1]]
+        warnings.warn(warning_msg, ODEintWarning, stacklevel=2)
+
+    if full_output:
+        output[1]['message'] = _msgs[output[-1]]
+
+    output = output[:-1]
+    if len(output) == 1:
+        return output[0]
+    else:
+        return output