sunos man page for isnan

isnan(3M)						  Mathematical Library Functions						 isnan(3M)

NAME
       isnan - test for NaN

SYNOPSIS
   C90 Mode
       cc [ flag... ] file... -lm [ library... ]
       #include <math.h>

       int isnan(double x);

   C99 Mode
       #include <math.h>

       int isnan(real--floating x);

DESCRIPTION
       In C90 mode, the isnan() function tests whether x is NaN.

       In  C99	mode,  the  isnan()  macro determines whether its argument value is NaN. First, an argument represented in a format wider than its
       semantic type is converted to its semantic type. The determination is then based on the type of the argument.

RETURN VALUES
       Both the isnan() function and macro return non-zero if and only if x is NaN.

ERRORS
       No errors are defined.

WARNINGS
       In C99 mode, the practice of explicitly supplying a prototype for isnan() after the line

       #include <math.h>

       is obsolete and will no longer work.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       fpclassify(3M), isfinite(3M), isinf(3M), isnormal(3M), math.h(3HEAD), signbit(3M), attributes(5), standards(5)

SunOS 5.10							    1 Dec 2003								 isnan(3M)