COPYSIGN
Section: Linux Programmer's Manual (3)
Updated: 20131014
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NAME
copysign, copysignf, copysignl  copy sign of a number
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(),
copysignf(),
and
copysignl()
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
Multithreading (see pthreads(7))
The
copysign(),
copysignf(),
and
copysignl()
functions are threadsafe.
CONFORMING TO
C99, POSIX.12001.
This function is defined in IEC 559 (and the appendix with
recommended functions in IEEE 754/IEEE 854).
NOTES
On architectures where the floatingpoint formats are not IEEE 754 compliant,
these
functions may treat a negative zero as positive.
SEE ALSO
signbit(3)
COLOPHON
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Index
 NAME

 SYNOPSIS

 DESCRIPTION

 RETURN VALUE

 ERRORS

 ATTRIBUTES

 Multithreading (see pthreads(7))

 CONFORMING TO

 NOTES

 SEE ALSO

 COLOPHON
