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 a float version of isinf(); it takes a float argument.  To use this function, compile either with the −Ae option or with the −Aa and −D_HPUX_SOURCE options.  Otherwise, the compiler promotes the float argument to double, and the function returns incorrect results. 

isinf() and isinff() are not specified by any standard, but isinff() is named in accordance with the conventions specified in the "Future Library Directions" section of the ANSI C standard. 

To use these functions, link in the math library by specifying −lm on the compiler or linker command line. 

ERRORS

No errors are defined. 

SEE ALSO

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

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996