NAME

isinf(), isinff() − test for INFINITY functions

SYNOPSIS

#include <math.h>

int isinf(double x);

int isinff(float x);

DESCRIPTION

isinf() returns a positive integer if x is +INFINITY, or a negative integer if x is −INFINITY.  Otherwise it returns zero. 

isinff() is the float version of isinf().  It is named in accordance with the conventions specified in the "Future Library Directions" section of the ANSI C standard.  Programs must be compiled in ANSI mode (use the -Aa option) in order to use this function; otherwise, the compiler promotes the float argument to double, and the function returns incorrect results. 

DEPENDENCIES

Series 300/400

isinff() is not supported on Series 300/400 systems. 

Series 700/800

isinff() is provided in the PA1.1 versions of the math library only.  The +DA1.1 option (the default on Series 700 systems) links in a PA1.1 version automatically.  A PA1.1 library can be linked in explicitly.  For more information, see the HP-UX Floating-Point Guide.

SEE ALSO

isnan(3M), fpclassify(3M), ieee(3M). 
 

Hewlett-Packard Company  —  HP-UX Release 9.10: April 1995