Just follow the built-in float('nan'):
In [594]: float('nan')**0
Out[594]: 1.0
In [595]: 1**float('nan')
Out[595]: 1.0
Aaron Meurer
On Tue, Feb 21, 2012 at 7:58 PM, Chris Smith <smi...@gmail.com> wrote:
> Quoting wikipedia's article on NaN:
>
> The 2008 version of the IEEE 754 standard says
> that pow(1,qNaN) and pow(qNaN,0) should both return 1 since they return 1
> whatever else is used instead of quiet NaN.
>
> To satisfy those wishing a more strict interpretation of how the power
> function should act, the 2008 standard defines two additional power
> functions; pown(x, n) where the exponent must be an integer, and powr(x,
> y) which returns a NaN whenever a parameter is a NaN or the exponentiation
> would give an indeterminate form.
>
>
> qNaN is a "quiet NaN"; the other type of NaN is a "signaling NaN":
> "Signaling NaNs, or sNaNs, are special forms of a NaN that when consumed by
> most operations should raise an invalid exception and then, if appropriate,
> be "quieted" into a qNaN that may then propagate." SymPy only has one type
> of NaN.
>
>
> We have a half-implemented version currently: S(1)**S.NaN == S.NaN but
> S(0)**S.NaN == S.One. So which way should we go?
>
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