anchor.diff:  
                     if (iface_coarse .eq. 0) then
                        i1 = 1-ibc
  -                     i2 = j+jc_add
  +                     j1 = j+jc_add
                     elseif (iface_coarse .eq. 1) then
                        i1 = mx+ibc
  -                     i2 = j+jc_add
  +    1                j1 = j+jc_add
                     endif
   
   c                 # Original code
  
positive.code: 
                    if (iface_coarse .eq. 2) then
                       i1 = i+ic_add
                       i2 = 1-jbc
                    elseif (iface_coarse .eq. 3) then
                       i1 = i+ic_add
                       i2 = my+jbc
                    endif
  
  c                 # Original code
  
negative.code:                      shifty = (jj - refratio/2.d0 - 0.5d0)/refratio
  
                       value = qc + shiftx*gradx + shifty*grady
  
                       ifine = ibc
                       jfine = (j-1)*refratio + jj
  