anchor.diff:           if (idir .eq. 0) then
   c           # this ensures that we get 'hanging' corners
   
  +            do ibc = 1,mbc/2
               if (iface_coarse .eq. 0) then
  -               ic = 1
  +               ic = ibc
               elseif (iface_coarse .eq. 1) then
  -               ic = mx
  +               ic = mx - ibc + 1
               endif
               do jc = 1,mx
                  i1 = ic
  
positive.code: 
        mth = 5
  
        if (icorner_coarse .eq. 0) then
           ic = 1
           jc = 1
        elseif (icorner_coarse .eq. 1) then
           ic = mx
           jc = 1
        elseif (icorner_coarse .eq. 2) then
           ic = 1
           jc = my
        elseif (icorner_coarse .eq. 3) then
           ic = mx
           jc = my
        endif
  
  c     # Interpolate coarse grid corners to fine grid corner ghost cells
  
negative.code:             qfine(iff,jff,mq) = value
           enddo
  
        enddo
        enddo 
        enddo
  
        end
  