signbit(3) [osx man page]

SIGNBIT(3)						   BSD Library Functions Manual 						SIGNBIT(3)

NAME

     signbit -- determine whether a floating-point number's sign is negative

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <math.h>

     int
     signbit(real-floating x);

DESCRIPTION

     The signbit() macro takes an argument of x.  It returns non-zero if the value of the argument's sign is negative, otherwise 0.

SEE ALSO

     fpclassify(3), math(3)

STANDARDS

     The signbit() macro conforms to ISO/IEC 9899:1999 (``ISO C99'').

BSD
								 February 11, 2003							       BSD

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

NAME

       signbit - test sign of a real floating-point number

SYNOPSIS

       #include <math.h>

       int signbit(x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       signbit():
	   _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
	   or cc -std=c99

DESCRIPTION

       signbit()  is  a  generic macro which can work on all real floating-point types.  It returns a nonzero value if the value of x has its sign
       bit set.

       This is not the same as x < 0.0, because IEEE 754 floating point allows zero to be signed.  The comparison -0.0 < 0.0 is false,	but  sign-
       bit(-0.0) will return a nonzero value.

       NaNs and infinities have a sign bit.

RETURN VALUE

       The signbit() macro returns nonzero if the sign of x is negative; otherwise it returns zero.

ERRORS

       No errors occur.

ATTRIBUTES

   Multithreading (see pthreads(7))
       The signbit() macro is thread-safe.

CONFORMING TO

       C99, POSIX.1-2001.  This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).

SEE ALSO

       copysign(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
								    2013-07-04								SIGNBIT(3)