NAME
        IEEEDPSub -- subtract one double precision IEEE number from another

   SYNOPSIS
          x   = IEEEDPSub(  y  ,  z  );
        d0/d1             d0/d1 d2/d3

        double  x,y,z;

   FUNCTION
        Compute x = y - z in IEEE double precision.

   INPUTS
        y -- IEEE double precision floating point value
        z -- IEEE double precision floating point value

   RESULT
        x -- IEEE double precision floating point value

   BUGS

   SEE ALSO
        ieeedpadd()