On Thu, Apr 30, 2009 at 3:01 AM, Colin Gillespie <c.gilles...@ncl.ac.uk> wrote:
>
> Hi,
>
> In the code:
>
>>>> x=sympify('pow(PZ,2)')
>>>> x
> pow(PZ, 2)
>>>> Poly(x,Symbol('PZ'))
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/data/ncsg3/pythonModules/lib/python2.5/site-packages/
> sympy-0.6.4-py2.5.egg/sympy/polys/polynomial.py", line 402, in __new__
> terms = Poly._decompose(poly, *symbols)
> File "/data/ncsg3/pythonModules/lib/python2.5/site-packages/
> sympy-0.6.4-py2.5.egg/sympy/polys/polynomial.py", line 545, in
> _decompose
> raise PolynomialError("Can't decompose %s" % factor)
> sympy.polys.polynomial.PolynomialError: Can't decompose pow(PZ, 2)
>
> Is this expected behaviour or should sympify convert pow(PZ,2) to
> PZ^2?
The sympify is indeed wrong. Could you debug what kind of "pow" it
generated? It's something different than if you type pow(PZ, 2)
yourself, as you can see here:
In [1]: sympify("pow(PZ, 2)")
Out[1]: pow(PZ, 2)
In [2]: var("PZ")
Out[2]: PZ
In [3]: pow(PZ, 2)
Out[3]:
2
PZ
Thanks,
Ondrej
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