anchor.diff:  c     # oriented identically.
   c     # ----------------------------------------------------------------------
   
  +c     # Routines that are still used :
  +c     # mb_exchange_corner_ghost
  +c     # mb_average_corner_ghost
  +c     # mb_average_block_corner_ghost
  +c     # mb_interpolate_corner_ghost  (at block boundaries)
  +
   
   c     # Exchange edge ghost data with neighboring grid at same level.
   c     # In the multiblock case, 'this' grid always initiates the exchange
  
positive.code:                   kc = areacoarse(i1,j1)
                    qcoarse(i1,j1,mq) = sum/kc
  
  c                 # Original code
  c                  sum = 0
  c                  do ii = 1,refratio
  c                     do jj = 1,refratio
  c                        ifine = (i-1)*refratio + ii
  c                        jfine = (jbc-1)*refratio + jj
  c                        if (iface_coarse .eq. 2) then
  c                           qf = qfine(ifine,jfine,mq)
  c                           kf = areafine(ifine,jfine)
  c                        else
  c                           qf = qfine(ifine,my+1-jfine,mq)
  c                           kf = areafine(ifine,my+1-jfine)
  c                        endif
  c                        sum = sum + kf*qf
  c                     enddo
  c                  enddo
  c                  if (iface_coarse .eq. 2) then
  c                     kc = areacoarse(i+ic_add,1-jbc)
  c                     qcoarse(i+ic_add,1-jbc,mq) = sum/kc
  c                  else
  c                     kc = areacoarse(i+ic_add,my+jbc)
  c                     qcoarse(i+ic_add,my+jbc,mq) = sum/kc
  c                  endif
                 enddo
              enddo
           endif
  
negative.code:       integer ic_add, jc_add, ic, jc, mth
        double precision shiftx, shifty, gradx, grady, qc, sl, sr, value
        double precision compute_slopes
  
        write(6,'(A,A)') 'mb_interpolate_face_ghost (ghost_twopatch.f) : ',
       &      'This has been replaced by a routine in claw2d_utils.f'
        stop
  
  c     # To be figured out later
        mth = 5
  