NaN comparisons - Call For Anecdotes

Marko Rauhamaa marko at
Thu Jul 17 21:10:08 CEST 2014

Chris Angelico <rosuav at>:

> numerical calculations might overflow to +inf or -inf, and then
> further calculations can result in a nan, etc, etc. Those are the
> sorts of examples that you'd find among SciPy users and such.

There is some inconsistency.

Mathematically, there are undefined operations, for a good reason.
That's because the limits are not unambiguous and that's why 0/0, 0**0,
1/0 and inf-inf are undefined.

Why 0/0 results in an exception but inf-inf = nan, I don't see a


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