isnan(3c)                  DG/UX 4.30                   isnan(3c)



     NAME
          isnan, isnand, isnanf - test for floating-point NaN (Not-a-
          Number)

     SYNOPSIS
          #include <ieeefp.h>

          int isnan (src)
          float src;
            or
          double src;

          int isnand (dsrc)
          double dsrc;

          int isnanf (fsrc)
          float fsrc;

     DESCRIPTION
          All three of these routines return true (1) if the argument
          is a NaN; otherwise they return false (0).

          The argument to isnan may be either single or double
          precision.

          These routines are implemented as macros included in
          <ieeefp.h>.  To access isnand as a function, the user may
          suppress the macro definition:

             #include <ieeefp.h>
             #undef isnand

          The isnand function is also accessed when <ieeefp.h> is not
          included.

     SEE ALSO
          fpgetround(3C).

     DIAGNOSTICS
          None of these routines generates any exception, even for
          signaling NaNs.














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