anchor.diff:                 if (.not. skip_this_grid) then
                     fineval = qfine_dummy(i2(1),j2(1),mq)
                     if (iface_coarse .eq. 0) then
  -c                    # Coarse face is right; fine grid is left
  +c                    # Coarse grid is right; fine grid is left
   c                    # efc0(0) is flux stored in the coarse grid 
   c                    # interior cell. 
  -                     deltac = fineval + fpcoarse0(jc,mq) + efc0(jc,mq,0)
  +                     deltac = fineval + fpcoarse0(jc,mq) - efc0(jc,mq,0)
                        areac = area0(jc)
  +
  +c                     write(6,'(2I3,6F14.8)') ic, jc,
  +c     &                       qcoarse(ic,jc,mq), fineval, 
  +c     &                       fpcoarse0(jc,mq), efc0(jc,mq,0),
  +c     &                       deltac, deltac/areac
  +
                     else
  -c                    # Coarse face is left; fine grid is right                    
  +c                   # Coarse grid is left; fine grid is right                    
   c                    # efc1(0) is flux stored in the coarse grid 
   c                    # interior cell. 
                        deltac = fineval + fmcoarse1(jc,mq) + efc1(jc,mq,0)
                        areac = area1(jc)
  -c                     write(6,'(1I5,5F16.8)') jc,
  -c     &                       qcoarse(ic,jc,mq), fineval, efc1(jc,mq,0),
  +
  +c                     write(6,'(2I3,6F14.8)') ic, jc,
  +c     &                       qcoarse(ic,jc,mq), fineval, 
  +c     &                       fmcoarse1(jc,mq), efc1(jc,mq,0),
   c     &                       deltac, deltac/areac
  +
                     endif   
                     qcoarse(ic,jc,mq) = qcoarse(ic,jc,mq) + deltac/areac
   
  
positive.code:             ii2 = 2*(i-1) + 2
              deltam = gmfine2(ii1,mq) + gmfine2(ii2,mq) +
       &               eff2(ii1,mq,1) + eff2(ii2,mq,1)
              deltap = gpfine3(ii1,mq) + gpfine3(ii2,mq) +
       &               eff3(ii1,mq,1) + eff3(ii2,mq,1)
              do ii = ii1,ii2
                 do jj = 1,mbc
                    qfine_dummy(ii,1-jj,mq) = -deltam
  
negative.code:                if (.not. skip_this_grid) then
                    fineval = qfine_dummy(i2(1),j2(1),mq)
                    if (iface_coarse .eq. 2) then
  c                    # Coarse is top grid  Fine grid is bottom grid; 
  c                    # efc2(0) is flux stored in the coarse grid 
  c                    # interior cell. 
                       deltac = fineval + gpcoarse2(ic,mq) - efc2(ic,mq,0)
                       areac = area2(ic)
                    else
  c                    # Coarse grid is bottom grid; fine is top grid   
  c                    # efc3(0) is flux stored in the coarse grid 
  c                    # interior cell.                   
                       deltac = fineval + gmcoarse3(ic,mq) + efc3(ic,mq,0)
  