SIGNBIT

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).