anchor.diff:  ! ---------------------------------------------------------------------------
   
   subroutine create_Hypre_grid(MPI_COMM_WORLD, hypre_grid, ilower, iupper, &
  -          num_procs, ierr)
  +          num_procs, myid, ierr)
  +  implicit none
   
     integer, intent(in) :: MPI_COMM_WORLD
     integer*8 :: hypre_grid
     integer :: num_procs
     integer :: ilower(0:num_procs-1,2), iupper(0:num_procs-1,2)
  +  integer :: myid
  +  integer :: ierr
  +
   
     call Hypre_StructGridCreate(MPI_COMM_WORLD, 2, hypre_grid, ierr)
   
  
positive.code:       MPI_COMM_WORLD, myid, num_procs, ilower, iupper, &
        hypre_grid)
    
  #ifdef useExtSolver
    ! Finalize MPI
    call MPI_Finalize(ierr)
  #endif
  
    stop 
  end program aronnax
  
negative.code:     ! 2*pi in this calculation
  #else
      ! use the external pressure solver
      call create_Hypre_A_vector(MPI_COMM_WORLD, hypre_grid, hypre_A, &
            a, nx, ny, freesurfFac, dt, ierr)
  #endif
  
      ! Check that the supplied free surface anomaly and layer
  