copysign(3) - Linux manual page (original) (raw)
copysign(3) Library Functions Manual copysign(3)
NAME top
copysign, copysignf, copysignl - copy sign of a number
LIBRARY top
Math library (_libm_, _-lm_)
SYNOPSIS top
**#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
DESCRIPTION top
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 top
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 top
No errors occur.
ATTRIBUTES top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ **Interface** │ **Attribute** │ **Value** │
├──────────────────────────────────────┼───────────────┼─────────┤
│ **copysign**(), **copysignf**(), **copysignl**() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
VERSIONS top
On architectures where the floating-point formats are not IEEE 754
compliant, these functions may treat a negative zero as positive.
STANDARDS top
C11, POSIX.1-2008.
This function is defined in IEC 559 (and the appendix with
recommended functions in IEEE 754/IEEE 854).
HISTORY top
C99, POSIX.1-2001, 4.3BSD.
SEE ALSO top
[signbit(3)](../man3/signbit.3.html)
COLOPHON top
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Linux man-pages 6.10 2024-07-23 copysign(3)
Pages that refer to this page:signbit(3)