ISNAN(3) |
Library Functions Manual |
ISNAN(3) |
NAME
isnan — test for not-a-number
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <math.h>
int
isnan(real-floating x);
DESCRIPTION
The
isnan() macro determines whether its argument
x is not-a-number (“NaN”). An argument represented in a format wider than its semantic type is converted to its semantic type first. The determination is then based on the type of the argument.
IEEE 754
It is determined whether the value of x is a NaN.
VAX
NaNs are not supported.
RETURN VALUES
The isnan() macro returns a non-zero value if the value of x is a NaN. Otherwise 0 is returned.
STANDARDS
The isnan() macro conforms to ISO/IEC 9899:1999 (“ISO C99”).