[daip] XSMTH

[Eric Greisen]

The task figures out the position in each input row corresponding to
the output pixel.  Then it finds the range of pixels in the input row
the corresponds to +- one support radius.  It weights these with the
Gaussian function into the output pixel.

The code is fairly straightforward

         LROW = TRC(1) - BLC(1) + 1.01         input size
         IROW = CATBLK(KINAX)                  output size
         XMUL = (LROW-1.0) / (IROW-1.0)
         XJ = 1.0 - XMUL
         XDIV = IXDIV                          # divisions/cell in
                                                lookup table
         DO 30 I = 1,IROW
            XJ = XJ + XMUL
            J1 = XJ - SUPRAD + 0.9999
            J2 = XJ + SUPRAD
            J1 = MAX (1, J1)
            J2 = MIN (LROW, J2)
            S = 0.0
            W = 0.0
            DO 10 J = J1,J2
               IF (XDATA(J).NE.FBLANK) THEN
                  L = ABS(XJ-J)*XDIV + 1.5
                  S = XDATA(J) * TAB(L) + S
                  W = TAB(L) + W
                  END IF
 10            CONTINUE
 20         RESULT(I) = FBLANK
            IF (W.GT.WCUTOF) RESULT(I) = S / W
 30         CONTINUE

Eric Greisen