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authorAndrew Kuchling <amk@amk.ca>2014-02-16 16:15:13 (GMT)
committerAndrew Kuchling <amk@amk.ca>2014-02-16 16:15:13 (GMT)
commit87a113b807b308215957f127f3696dca58c08253 (patch)
tree92924718e574cae7d5dfac8f8fcff0cd7ee0dcd3 /Doc
parentf7b2f36f747179cf3dc7a889064f8979e3ad4dae (diff)
parent8cb1ec3274fff35a3613dd9fa8f0c99b4f472119 (diff)
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Merge from 3.3
Diffstat (limited to 'Doc')
-rw-r--r--Doc/library/math.rst7
1 files changed, 5 insertions, 2 deletions
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 7c3ab59..0083409 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -36,9 +36,12 @@ Number-theoretic and representation functions
.. function:: copysign(x, y)
- Return *x* with the sign of *y*. On a platform that supports
- signed zeros, ``copysign(1.0, -0.0)`` returns *-1.0*.
+ Return a float with the magnitude (absolute value) of *x* but the sign of
+ *y*. On platforms that support signed zeros, ``copysign(1.0, -0.0)``
+ returns *-1.0*.
+ If *x* is NaN, *y* is ignored and NaN is returned. If *y* is NaN,
+ it is treated as positive: ``copysign(-1.0, NaN)`` returns 1.0.
.. function:: fabs(x)