NAME

isinf, isnan − test for indeterminate floating-point values

SYNOPSIS

int isinf(value)
double value;

int isnan(value)
double value;

DESCRIPTION

Isinf returns a value of 1 if its value is an IEEE format infinity (two words 0x7ff00000 0x00000000) or an IEEE negative infinity, and returns a zero otherwise. 

Isnan returns a value of 1 if its value is an IEEE format ‘not-a-number’ (two words 0x7ffnnnnn0xnnnnnnnn) where n is not zero) or its negative, and returns a zero otherwise. 

Some library routines such as ecvt(3) do not handle indeterminate floating-point values gracefully. Prospective arguments to such routines should be checked with isinf or isnan before calling these routines. 

The Floating-Point Programmer’s Guide for the Sun Workstation gives details for the format of IEEE standard floating-point. 

Sun Release 3.2  —  Last change: 8 August 1985