copysign(3)

1COPYSIGN(3)                Linux Programmer's Manual               COPYSIGN(3)
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NAME

6       copysign, copysignf, copysignl - copy sign of a number
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SYNOPSIS

9       #include <math.h>
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11       double copysign(double x, double y);
12       float copysignf(float x, float y);
13       long double copysignl(long double x, long double y);
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15       Link with -lm.
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       copysign(), copysignf(), copysignl(): _SVID_SOURCE || _BSD_SOURCE ||
20       _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
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DESCRIPTION

23       The copysign() functions return a value whose  absolute  value  matches
24       that of x, but whose sign bit matches that of y.
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RETURN VALUE

27       On  success,  these  functions  return a value whose magnitude is taken
28       from x and whose sign is taken from y.
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30       If x is a NaN, a NaN with the sign bit of y is returned.
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ERRORS

33       No errors occur.
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CONFORMING TO

36       C99, POSIX.1-2001.  This function is defined in IEC 559 (and the appen‐
37       dix with recommended functions in IEEE 754/IEEE 854).
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NOTES

40       On architectures where the floating-point formats are not IEEE 754 com‐
41       pliant, the copysign() functions may treat a negative zero as positive.
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COLOPHON

47       This page is part of release 3.25 of the Linux  man-pages  project.   A
48       description  of  the project, and information about reporting bugs, can
49       be found at http://www.kernel.org/doc/man-pages/.
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53GNU                               2008-08-05                       COPYSIGN(3)