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| author |   Mark Dickinson <mdickinson@enthought.com> | 2020-04-05 10:25:24 +0100 |
|---|---|---|
| committer |   GitHub <noreply@github.com> | 2020-04-05 10:25:24 +0100 |
| commit | 810f68f1282c917fc1ad6af540a9f08524dfe310 (patch) | |
| tree | 43f8c2bf8be6e32f1e4bf3084280b0f923bedef2 /Doc/reference | |
| parent | bpo-40190: Add support for _SC_AIX_REALMEM in sysconf (GH-19380) (diff) | |
| download | cpython-810f68f1282c917fc1ad6af540a9f08524dfe310.tar.gz cpython-810f68f1282c917fc1ad6af540a9f08524dfe310.tar.bz2 cpython-810f68f1282c917fc1ad6af540a9f08524dfe310.zip | |
Fix misinformation about NaN != NaN comparison (GH-19357)
Diffstat (limited to 'Doc/reference')
| -rw-r--r-- | Doc/reference/expressions.rst | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index 16542cdcec1..8036a491c29 100644 --- a/Doc/reference/expressions.rst +++ b/Doc/reference/expressions.rst @@ -1422,8 +1422,9 @@ built-in types. The not-a-number values ``float('NaN')`` and ``decimal.Decimal('NaN')`` are special. Any ordered comparison of a number to a not-a-number value is false. A counter-intuitive implication is that not-a-number values are not equal to - themselves. For example, if ``x = float('NaN')``, ``3 < x``, ``x < 3``, ``x - == x``, ``x != x`` are all false. This behavior is compliant with IEEE 754. + themselves. For example, if ``x = float('NaN')``, ``3 < x``, ``x < 3`` and + ``x == x`` are all false, while ``x != x`` is true. This behavior is + compliant with IEEE 754. * ``None`` and ``NotImplemented`` are singletons. :PEP:`8` advises that comparisons for singletons should always be done with ``is`` or ``is not``, |