Name

signbit — test sign of a real floating point number

Synopsis

#include <math.h>
int signbit(   X);
[Note] Note

Compile with −std=c99; link with −lm.

DESCRIPTION

`signbit' is a generic macro which can work on all real floating-point types. It returns a non-zero 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 non-zero value.

CONFORMING TO

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

SEE ALSO

copysign(3)


  Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
Distributed under GPL
Based on glibc infopages