NAME
        IEEEDPFloor -- compute Floor function of IEEE double precision number

   SYNOPSIS
          x   = IEEEDPFloor(  y  );
        d0/d1               d0/d1

        double  x,y;

   FUNCTION
        Calculate the largest integer less than or equal to x and return it.
        This value may have more than 32 bits of significance.

   INPUTS
        y -- IEEE double precision floating point value

   RESULT
        x -- IEEE double precision floating point value

   BUGS

   SEE ALSO
        ieeedpceil()