ISNAN(3) BSD Library Functions Manual ISNAN(3)NAMEisnan — 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.
RETURN VALUES
The isnan() macro returns a non-zero value if the value of x is a NaN.
Otherwise 0 is returned.
SEE ALSOfpclassify(3), isfinite(3), isinf(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”).
BSD March 5, 2004 BSD