diff options
Diffstat (limited to 'Doc/library/math.rst')
| -rw-r--r-- | Doc/library/math.rst | 7 |
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) |