anchor.diff:         call write_netcdf(grid(lev)%cA,vname='ca',netcdf_file_name='cA.nc',rank=myrank,iter=lev)
       endif
   
  -  end subroutine define_matrix
  +  end subroutine define_matrix_orig
   
   end module mg_define_matrix
  
positive.code:                ( zw(k+1,j,i) - zw(k,j,i) + zw(k+1,j-1,i) - zw(k,j-1,i) ) * &
                 (dx(j,i)+dx(j-1,i)) ) / ( hlf * (dy(j,i)+dy(j-1,i)) ) & ! couples with j-1
                 + qrt * ( &
                 (( hlf * (zr(k,j,i  )-zr(k,j-2,i  )) / dy(j-1,i) ) * dx(j-1,i)) - &
                 (( hlf * (zr(k,j+1,i  )-zr(k,j-1,i  )) / dy(j,i) ) * dx(j,i)) )
            cA(5,k,j,i) =- qrt * ( &
                 (( hlf * (zr(k-1,j+1,i  )-zr(k-1,j-1,i  )) / dy(j,i) ) * dx(j,i)) + &
                 (( hlf * (zr(k,j,i  )-zr(k,j-2,i  )) / dy(j-1,i) ) * dx(j-1,i)) )     ! couples with k-1 j-1
  
negative.code: 
         ! Define matrix coefficients from dx, dy, zr and zw coarsened
         call define_matrix(lev, grid(lev)%dx, grid(lev)%dy, grid(lev)%zr, grid(lev)%zw)
  !!$       call define_matrix_orig(lev, grid(lev)%dx, grid(lev)%dy, grid(lev)%zr, grid(lev)%zw)
  
      enddo ! lev
  
  