anchor.diff:      end do
   
       call HYPRE_StructMatrixCreate(MPI_COMM_WORLD, hypre_grid, stencil, hypre_A, ierr)
  +
       call HYPRE_StructMatrixInitialize(hypre_A, ierr)
   
       ! nentries = 5 ! a five point stncil means five entries for each grid point
  
positive.code: 
      ! print *, 'here'
    etanew = etanew*wetmask
    call wrap_fields_2D(etanew, nx, ny)
  
    ! Now update the velocities using the barotropic tendency due to
  
negative.code:   ! call HYPRE_ParCSRPCGGetFinalRelative(hypre_solver, & 
    !   temp(2), ierr)
    ! print *, 'final residual norm = ', temp(2)
  
    do i = 0, num_procs-1
      call HYPRE_StructVectorGetBoxValues(hypre_x, & 
        ilower(i,:), iupper(i,:), values, ierr)
  