Allow for different mult complexity on each side

julia/sr.jl

@@ -548,7 +548,7 @@ function combineOperators(tree::Node)::Node
     top_level_constant = tree.degree == 2 && (tree.l.constant || tree.r.constant)
     if tree.degree == 2 && (binops[tree.op] === mult || binops[tree.op] === plus) && top_level_constant
         op = tree.op
-        # Put the constant in r
+        # Put the constant in r. Need to assume var in left for simplification assumption.
         if tree.l.constant
             tmp = tree.r
             tree.r = tree.l

pysr/sr.py

@@ -259,9 +259,15 @@ def pysr(X=None, y=None, weights=None,
     for op in binary_operators:
         if op not in constraints:
             constraints[op] = (-1, -1)
-        if op in ['mult', 'plus', 'sub']:
+        if op in ['plus', 'sub']:
             if constraints[op][0] != constraints[op][1]:
-                raise NotImplementedError("You need equal constraints on both sides for +, -, and *, due to simplification strategies.")
+                raise NotImplementedError("You need equal constraints on both sides for - and *, due to simplification strategies.")
+        elif op == 'mult':
+            # Make sure the complex expression is in the left side.
+            if constraints[op][0] == -1:
+                continue 
+            elif constraints[op][1] == -1 or constraints[op][0] < constraints[op][1]:
+                constraints[op][0], constraints[op][1] = constraints[op][1], constraints[op][0]
 
     constraints_str = "const una_constraints = ["
     first = True