signbit

SIGNBIT(3)                    libc math functions                   SIGNBIT(3)



NAME
       signbit - test sign of a real floating point number

SYNOPSIS
       #include <math.h>

       int signbit (X);


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
       `signbit (-0.0)' will return a nonzero value.

CONFORMING TO
       This  function is defined in IEC 559 (and the appendix with recommended
       functions in IEEE 754/IEEE 854).

SEE ALSO
       copysign(3)



GNU                               2002-08-10                        SIGNBIT(3)