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Created on 2022-03-15 00:45 by w0rthle$$, last changed 2022-04-11 14:59 by admin. This issue is now closed.
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| msg415213 - (view) | Author: Pablo Dumas (w0rthle$$) | Date: 2022-03-15 00:45 | |
float('nan')==math.nan does NOT evaluate to True (as suggested by documentation).
On the other hand, float('inf')==math.inf DOES evaluate to True (as suggested by documentation).
Documentation we're referring to: https://docs.python.org/3.8/library/math.html
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| msg415214 - (view) | Author: Jelle Zijlstra (JelleZijlstra) *  |
Date: 2022-03-15 01:05 | |
I'm guessing you're referring to https://docs.python.org/3.8/library/math.html#math.nan. The text says explicitly that math.nan is "equivalent" to float("nan"), not that it is equal. This is correct. nan is not equal to itself, because (for better or worse) that's what the IEEE standard requires. You can instead use math.isnan() to check whether a number is a nan. |
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| msg415215 - (view) | Author: Eric V. Smith (eric.smith) * |
Date: 2022-03-15 01:21 | |
Jelle gives the correct reason for what you're seeing.
Also note:
>>> math.nan == math.nan
False
>>> float('nan') == float('nan')
False
If there's some specific part of the documentation that you think is misleading, please reopen this and point us to the wording that's confusing.
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:57 | admin | set | github: 91176 |
| 2022-03-15 01:21:51 | eric.smith | set | status: open -> closed nosy: + eric.smith messages: + msg415215 resolution: not a bug stage: resolved |
| 2022-03-15 01:05:59 | JelleZijlstra | set | nosy:
+ JelleZijlstra messages: + msg415214 |
| 2022-03-15 00:45:19 | w0rthle$$ | create | |