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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

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       description of the project, and information about reporting  bugs,  can
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