HP-UX Reference (11i v2 04/09) - 3 Library Functions N-Z (vol 7)

signbit(3M) signbit(3M)

NAME

signbit() - ﬂoating-point sign-determination

SYNOPSIS

#include <math.h>

int signbit(ﬂoating-type x);

DESCRIPTION

The signbit() macro determines whether the sign of its argument value (which may be a ﬂoating-

point number, zero, inﬁnity, or NaN) is negative. The argument must be of ﬂoating type. For

Itanium(R)-based systems, the argument can be any ﬂoating type. For PA-RISC, the argument must be

either double or float.

USAGE

To use the

signbit() macro, compile either with the default

-Ae option or with the -Aa and

-D_HPUX_SOURCE

options. Make sure your program includes <math.h>. Link in the math library by

specifying

-lm on the compiler or linker command line.

RETURN VALUE

The

signbit() macro returns a nonzero value if and only if the sign of its argument value is negative.

The macro raises no exceptions.

ERRORS

No errors are deﬁned.

EXAMPLES

Take certain actions if

x is negative zero:

#include <math.h>

/*...*/

double x;

/*...*/

if ( (x == 0.0) && signbit(x) ) {

/*...*/

}