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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 || _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.
CONFORMING TO
       C99, POSIX.1-2001.  This function is defined in IEC 559 (and the appen-
       dix 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 3.53 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                               2012-03-25                       COPYSIGN(3)