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Match doesn't respect matrix non-commutativity #17172

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anpandey opened this issue Jul 10, 2019 · 0 comments

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@anpandey
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commented Jul 10, 2019

match doesn't obey the commutativity of matrix expressions when matching scalars between two expressions. As a demonstration:

>>> from sympy.abc import N
>>> A, B, C, D = map(lambda x: MatrixSymbol(x, N, N), ['A', 'B', 'C', 'D'])
>>> w = Wild('w')
>>> a, b = symbols('a b')
>>> e1 = a * b * (A * B * C * D)
>>> e2 = w * (D * C * B * A)
>>> e1.match(e2)
{w_: a*b}

e1.match(e1) should be None, since the associated matrix multiplications are in a different order (and so not indentical).

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