Interestingly, with noevalMul:

noevalMul(2, 3)
>>> 2*3

noevalMul(-2, 3)
>>> -6


occurs because of some combination of "as_coeff_Mul" and "_keep_coeff", and
the SymPy printer calls the "_keep_coeff" owned by Mul, not noevalMul, so
I'm not sure how to override this behaviour in noevalMul.



On 12 October 2013 01:21, Ben Lucato <[email protected]> wrote:

> This is awesome!!! Your simple fix with overriding flatten() works
> perfectly. My last question is -- how do you do the same thing with Pow? It
> is subclassed differently to Add, Mul (which both subclass "AssocOp").
> I have taken a look at the source code (go me!!!) - it seems that in this
> case, because Pow is defined like this:
>
> "def __new__(cls, b, e, evaluate=True):
>  b = _sympify(b) e = _sympify(e) if evaluate: if e is S.Zero: return S.One
> elif e is S.One: return b else: obj = b._eval_power(e) if obj is not None:
> return obj obj = Expr.__new__(cls, b, e) obj.is_commutative = (b.
> is_commutative and e.is_commutative) return obj"
>
>
> So it seems a change to __new__ is necessary, right? It looks like
> evaluate=False is not even supported for Pow - am I right? (just a noob
> asking questions)
>
> Thanks!!
>



-- 


Ben Lucato
----------------------------------------------------------------------------------
Phone: +61 400 159 632 | Email: [email protected]

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