copysign, copysignf, copysignl - copy sign of a number
Math library (
libm,
-lm)
#include <math.h>
double copysign(double x, double y);
float copysignf(float x, float y);
long double copysignl(long double x, long double y);
copysign(),
copysignf(),
copysignl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
These functions return a value whose absolute value matches that of
x,
but whose sign bit matches that of
y.
For example,
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
y.
If
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).
Interface |
Attribute |
Value |
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.
signbit(3)