copysign3
Copy sign of a number
Usage
#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)):
copysign(), copysignf(), copysignl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Library
Math library (libm, -lm)
Overview
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.
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.
Attributes
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| copysign(), copysignf(), copysignl() | Thread safety | MT-Safe |
Versions
On architectures where the floating-point formats are not IEEE 754 compliant, these functions may treat a negative zero as positive.
Releases
19 releases since Debian 1.1 (Buzz); the text changed 13 times.