[issue28579] nan != nan
Liam Marsh
report at bugs.python.org
Tue Nov 1 11:00:37 EDT 2016
New submission from Liam Marsh:
I found a really weird comportment with NANs:
>>> from math import nan, isnan, inf
>>> nan==nan
False
>>> nan!=nan
True
>>> a=nan # maybe get another instance would fix it (or so I thought)
>>> a==nan
False
>>> a==a
False
>>> a is a
True
>>> # because `is` works, it could be a
>>> # deliberate comportment. is it?
>>> a is nan
True
>>> isnan(a) and isnan(nan)
True
>>> nan == -nan
False
>>> nan is -nan
False
>>> a < 1
False
>>> a > 0
False
>>> a < inf
False
>>> b=external_pyd_call_that_returns_nan()
>>> isnan(b)
True
>>> b == nan
False
that sums what I tried up.
thanks for reading this.
----------
messages: 279878
nosy: niacdoial
priority: normal
severity: normal
status: open
title: nan != nan
type: behavior
versions: Python 3.5
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<http://bugs.python.org/issue28579>
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