Manual Reference Pages - COPYSIGN (3)
NAME
copysign, copysignf, copysignl - copy sign of a number
CONTENTS
Synopsis
Description
Return Value
Errors
Notes
Colophon
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 ||
_POSIX_C_SOURCE >= 200112L;
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 .
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.
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
signbit (3)
COLOPHON
This page is part of release 3.44 of the Linux
man-pages project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages /.

GNU
COPYSIGN (3)
2012-03-25

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