RedHat 5.2

GNU/Linux	RedHat 5.2 (Apollo)
	isnan(3)

ISINF

NAME

isinf, isnan, finite − test for infinity or not-a-number (NaN)

#include <math.h>

int isinf(double value);

int isnan(double value);

int finite(double value);

The isinf() function returns −1 if value represents negative infinity, 1 if value represents positive infinity, and 0 otherwise.

The isnan() function returns a non-zero value if value is "not-a-number" (NaN), and 0 otherwise.

The finite() function returns a non-zero value if value is neither infinite nor a "not-a-number" (NaN) value, and 0 otherwise.

BSD 4.3

isnan(3)