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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; 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.

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 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                               2008-08-05                       COPYSIGN(3)