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 a float version of isnan(); it takes a float argument.  To use this function, compile either with the −Ae option or with the −Aa and −D_HPUX_SOURCE options.  Otherwise, the compiler promotes the float argument to double, and the function returns incorrect results. 

isnanf() is not specified by any standard, but it is named in accordance with the conventions specified in the "Future Library Directions" section of the ANSI C standard. 

To use these functions, link in the math library by specifying −lm on the compiler or linker command line. 

ERRORS

No errors are defined. 

SEE ALSO

finite(3M), fpclassify(3M), isinf(3M). 

STANDARDS CONFORMANCE

isnan(): SVID3, XPG4.2

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996