HP-UX Reference (11i v3 07/02) - 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 is a NaN. The argument must be of floating type.
For HP Integrity servers, the argument can be any floating type. For PA-RISC, the argument must be
either double or float.
The isnan() macro implements the isnan() functionality recommended by the IEEE-754 standard for
floating-point arithmetic.
The isnan() macro replaces the isnan() and
isnanf() functions, which are obsolete and are no
longer supported.
USAGE
To use the
isnan() 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.
RETURN VALUE
The isnan() macro returns a nonzero value if and only if its argument has a NaN value. The macro
raises no floating-point exceptions.
ERRORS
No errors are defined.
EXAMPLES
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(): ISO/IEC C99
706 Hewlett-Packard Company − 1 − HP-UX 11i Version 3: February 2007