Test for a NaN. Returns 1 if the argument is NaN; 0 if not.

    This function is supported on OpenVMS Integrity servers and
    Alpha only.

    Format

      #include  <math.h>

      int isnan  (double x);

      int isnanf  (float x);

      int isnanl  (long double x);

  Additional Information (explode) :

• Argument
• Description