ISNAN(3) BSD Programmer's Manual ISNAN(3)NAME
isnan - test for not-a-number
LIBRARY
libc
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 ALSOfpclassify(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").
MirOS BSD #10-current March 5, 2004 1