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Mon Nov 9 23:51:09 CET 2009 · https://mail.python.org/pipermail/python-dev/2009-November/093976.html

Mark Dickinson wrote:

> That's because you're creating two different float nans.
> Compare with:
> 
> Python 3.2a0 (py3k:76132M, Nov  6 2009, 14:47:39)
> [GCC 4.2.1 (SUSE Linux)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
>>>> nan = float('nan')
>>>> d = {nan: 10, 0: 20}
>>>> nan in d
> True
>>>> d[nan]
> 10

This also suggests to me that nan should be a singleton, or at least 
that the doc should recommend that programs should make it be such for 
the program.

tjr

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Showing content from https://mail.python.org/pipermail/python-dev/2009-November/093976.html below:

[Python-Dev] decimal.py: == and != comparisons involving NaNs