comparing nan "number"

[Michael Hudson]

jjl at pobox.com (John J. Lee) writes:

> Boštjan Jerko <bostjan.jerko at mf.uni-lj.si> writes:
> 
> > I need to know if the result of math formula is nan (Not a number). 
> > How can I do that?
> 
> I suppose:
> 
> NAN = any_calculation_that_returns_nan()
> 
> if some_other_calculation() is NAN:
>     ...

I wouldn't expect that to work.  Unfortunately, I don't think there is
a reliable way.

result = some_calculation()
if result != result:
    # it's a nan

*might* work, depending probably on compiler, Python version, platform
and phase of the moon.

Cheers,
mwh

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