On Mar 1, 2:00 pm, Addison Cugini <[email protected]> wrote:
> I have run into a problem when multiplying several square-roots together
> with a non-commutative object.
>
> In [19]: str(Symbol('x', commutative=False)*sqrt(2)/sqrt(6))
> Out[19]: 3**(1/2)/3
>
> It looks like some function that is called in Mul's constructor is dropping
> the non-commutative object somewhere. I don't know the code well enough to
> find the particular location where this is happening, but it looks like a
> bug.
>
> Cheers,
> Addison Cugini
You're right there's a bug there. When things like sqrt(2)/sqrt(6) can
be simplified there is a second run through "flatten" but it does not
carry the non-commutative part. Here's a patch fixing it:
diff --git a/sympy/core/mul.py b/sympy/core/mul.py
index 4ca70b1..0ba2ffa 100644
--- a/sympy/core/mul.py
+++ b/sympy/core/mul.py
@@ -304,7 +304,7 @@ def flatten(cls, seq):
c_part = [Add(*[coeff*f for f in c_part[1].args])]
if reeval:
- return Mul.flatten(c_part)
+ return Mul.flatten(c_part+nc_part)
return c_part, nc_part, order_symbols
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