copysign, copysignf, copysignl - copy sign of a number
#include <math.h> double copysign(double x, double y); float copysignf(float x, float y); long double copysignl(long double x, long double y);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
These functions return a value whose absolute value matches that of
x, but whose sign bit matches that of
copysign(42.0, -1.0) and
copysign(-42.0, -1.0) both return -42.0.
On success, these functions return a value whose magnitude is taken from
x and whose sign is taken from
x is a NaN, a NaN with the sign bit of
y is returned.
No errors occur.
For an explanation of the terms used in this section, see attributes(7).
|copysign(), copysignf(), copysignl()||Thread safety||MT-Safe|
C99, POSIX.1-2001, POSIX.1-2008. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
On architectures where the floating-point formats are not IEEE 754 compliant, these functions may treat a negative zero as positive.
This page is part of release 5.10 of the Linux
man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.