gh-135308: clarify math.issubnormal() description #135324
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bedevere-app
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Small related problem. If you follow to sys.float_info.min - you find yourself in the middle of the |
nedbat
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Jun 10, 2025
picnixz
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StanFromIreland
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encukou
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| @@ -387,8 +387,8 @@ Floating point manipulation functions | |||
| .. function:: issubnormal(x) | |||
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| Return ``True`` if *x* is a subnormal number, that is a finite | |||
| nonzero number with a magnitude smaller than the smallest positive normal | |||
| number, see :data:`sys.float_info.min`. Return ``False`` otherwise. | |||
| nonzero number with a magnitude smaller than :data:`sys.float_info.min`. | |||
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The magnitude is an integer, it'll be smaller than sys.float_info.min if x is smaller than 1.
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| nonzero number with a magnitude smaller than :data:`sys.float_info.min`. | |
| nonzero number smaller than :data:`sys.float_info.min`. |
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I guess the original meant “smaller than the magnitude of the smallest positive normal number”, but that's just extra words.
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This will be incorrect, as any finite negative floating-point number will satisfy your definition.
The magnitude is an integer
No. It's about absolute value of the float. See e.g. copysign() docs.
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math.isnormalandmath.issubnormalreferring to "normality" without context #135308📚 Documentation preview 📚: https://cpython-previews--135324.org.readthedocs.build/
https://cpython-previews--135324.org.readthedocs.build/en/135324/library/math.html#math.issubnormal