HP-UX Reference (11i v1 05/09) - 3 Library Functions A-M (vol 6)

i
isnan(3M) isnan(3M)
NAME
isnan() - floating-point test for NaN
SYNOPSIS
#include <math.h>
int isnan(
floating-type x);
DESCRIPTION
The isnan() macro determines whether its argument value is a NaN. The macro can be used with either
double or float arguments.
The ISO/ANSI C committee has approved the
isnan() macro for inclusion in the forthcoming C9X draft
standard. The
isnan() macro implements the isnan() function recommended by the IEEE-754 stan-
dard for floating-point arithmetic.
To use this macro, compile either with the default
-Ae option or with the -Aa and -D_HPUX_SOURCE
options. Make sure your program includes <
math.h>. Link in the math library by specifying -lm on the
compiler or linker command line.
The
isnan() macro replaces the isnan() and isnanf() functions, which are obsolete and are no
longer supported.
RETURN VALUE
The isnan() macro returns a nonzero value if and only if its argument has a NaN value.
ERRORS
No errors are defined.
EXAMPLE
Take certain actions if x is not a NaN:
#include <math.h>
/*...*/
double x;
/*...*/
if (!isnan(x))
/*...*/
SEE ALSO
fpclassify(3M), isfinite(3M), isinf(3M), isnormal(3M), signbit(3M), math(5).
STANDARDS CONFORMANCE
isnan(): SVID3, XPG4.2
HP-UX 11i Version 1: September 2005 − 1 − Hewlett-Packard Company Section 3−−509