COPYSIGN(3)                         Linux Programmer's Manual                         COPYSIGN(3)



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 thread-safe.

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, these func‐
       tions may treat a negative zero as positive.

SEE ALSO
       signbit(3)

COLOPHON
       This page is part of release 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



GNU                                         2013-10-14                                COPYSIGN(3)