copysign

(3)

copy sign of a number

Library functionsmanpages-dev 6.9.1-1also documents copysignf, copysignl

#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

LIBRARY

Math library (libm, -lm)

DESCRIPTION

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

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).

Interface	Attribute	Value
copysign (), copysignf (), copysignl ()	Thread safety	MT-Safe

VERSIONS

On architectures where the floating-point formats are not IEEE 754 compliant, these functions may treat a negative zero as positive.

STANDARDS

C11, POSIX.1-2008.

This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).

HISTORY

C99, POSIX.1-2001, 4.3BSD.