test for nan

[Peter Maas]

Peter Maas wrote:
> John Hunter wrote:
>> Is there a better way to test for NaN than
>>
>>    str(p1)=='nan'
>>
>> where p1 is a float?
> [...]
> As far as I know NaN is th only value that yields false when compared
> to itself. This leads to
> 
 > def isNaN(x):
 >     return (x == x) == False

Shorter:

def isNaN(x):
     return x != x

Mit freundlichen Gruessen,

Peter Maas

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