NAME

isnan(), isnanf() − test for NaN functions

SYNOPSIS

#include <math.h>

int isnan(double x);

int isnanf(float x);

DESCRIPTION

isnan() returns a nonzero integer if x is NaN (not-a-number).  Otherwise it returns zero. 

isnanf() is the float version of isnan().  Programs must be compiled in ANSI mode (use the -Aa option) in order to use this function; otherwise, the compiler promotes the float argument to double, and the function returns incorrect results. 

DEPENDENCIES

Series 300/400

isnanf() is not supported on Series 300/400 systems. 

Series 700/800

isnanf() is not specified by any standard; however, it is named in accordance with the conventions specified in the "Future Library Directions" section of the ANSI C standard.  It is provided in the PA1.1 versions of the math library only.  The +DA1.1 option (the default on Series 700 systems) links in a PA1.1 version automatically.  A PA1.1 library can be linked in explicitly.  For more information, see the HP-UX Floating-Point Guide.

SEE ALSO

isinf(3M), fpclassify(3M), ieee(3M). 

STANDARDS CONFORMANCE

isnan() in libm.a: AES, XPG3
isnan() in libM.a: AES, XPG3, XPG4

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992