isnan(3M)

NAME

     isnan - test for NaN

SYNOPSIS

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

     int isnan(double x);

DESCRIPTION

     The isnan() function tests whether x is NaN.

RETURN VALUES

     The isnan() function returns non-zero if x  is  NaN.  Other-
     wise, 0 is returned.

USAGE

     On systems not supporting NaN, isnan() always returns 0.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|

SEE ALSO

     attributes(5)