COPYSIGN

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
NOTES
SEE ALSO
COLOPHON

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() 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).

Image grohtml-126021.png

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

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