Updates:
Labels: EasyToFix NeedsReview
Comment #3 on issue 1261 by asmeurer: incorrect exponentiation with
non-commutative symbols
http://code.google.com/p/sympy/issues/detail?id=1261
This also holds true for exp(x)*exp(y). powsimp cannot maintain
commutativity of the arguments unless exp(x).is_commutative is the same as
x.is_commutative. It looks like a lot of things are not doing this
correctly.
>>> x.is_commutative
False
>>> exp(x).is_commutative
True
>>> sin(x).is_commutative
True
Not even addition gets it right:
>>> y.is_commutative
False
>>> x+y
x + y
>>> y+x
x + y
This should be easy to fix. Add.py just needs to be refactored so that the
noncommutative parts do not order (see Mul for how this is done). To fix
the
problem in the original post, I think Mul needs to be modified ((x*y/x)**2
is a Mul). I have attached a patch that fixes functions being commutative
when the
arguments are not.
Attachments:
0001-Made-Function-return-is_commutative-False-if-any.patch 1.6 KB
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