ISNAN(3) Library Functions Manual ISNAN(3)

NAME

isnantest 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.

SEE ALSO

fpclassify(3), isfinite(3), isinf(3), isinff(3), isnanf(3), isnormal(3), math(3), signbit(3)

IEEE Standard for Binary Floating-Point Arithmetic, Std 754-1985, ANSI.

STANDARDS

The isnan() macro conforms to ISO/IEC 9899:1999 (“ISO C99”).
March 5, 2004 NetBSD 6.1