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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
COPYSIGN(3) Linux Programmer's Manual COPYSIGN(3)
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);
Link with -lm.
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 versions <= 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)
This page is part of release 4.12 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/.
GNU 2016-03-15 COPYSIGN(3)
Pages that refer to this page: signbit(3)