From 810f68f1282c917fc1ad6af540a9f08524dfe310 Mon Sep 17 00:00:00 2001 From: Mark Dickinson Date: Sun, 5 Apr 2020 10:25:24 +0100 Subject: Fix misinformation about NaN != NaN comparison (GH-19357) --- Doc/reference/expressions.rst | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index 16542cd..8036a49 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``, -- cgit v0.12