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



NAME
       copysign, copysignf, copysignl - copy sign of a number

SYNOPSIS
       #include <&lt;math.h>&gt;

       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.  If x is a NaN, then a
       NaN with the sign bit of y is returned.

CONFORMING TO
       C99, 4.3BSD.  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 com-
       pliant, the copysign() functions may treat a negative zero as positive.

SEE ALSO
       signbit(3)

COLOPHON
       This page is part of release 3.05 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



GNU                               2007-07-26                       COPYSIGN(3)