copysign(3)
NAME
copysign, copysignf, copysignl - copy sign of a number
SYNOPSIS
#include <math.h> double copysign(double x, double y); float copysignf(float x, float y); long double copysignl(long double x, long double y); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): copysign(), copysignf(), copysignl(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
DESCRIPTION
The copysign() functions return a value whose absolute value matches
that of x, but whose sign bit matches that of y.
RETURN VALUE
On success, these functions return a value whose magnitude is taken
from x and whose sign is taken from y.
If x is a NaN, a NaN with the sign bit of y is returned.
ERRORS
No errors occur.
CONFORMING TO
C99, POSIX.1-2001. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
NOTES
On architectures where the floating-point formats are not IEEE 754 compliant, the copysign() functions may treat a negative zero as positive.
SEE ALSO
COLOPHON
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