anchor.diff:    call HYPRE_StructVectorCreate(MPI_COMM_WORLD, hypre_grid, hypre_x, ierr)
     call HYPRE_StructVectorInitialize(hypre_x, ierr)
   
  -  do i = 0, num_procs-1
  -    call HYPRE_StructVectorSetBoxValues(hypre_x, &
  +  ! do i = 0, num_procs-1
  +  call HYPRE_StructVectorSetBoxValues(hypre_x, &
         ilower(i,:), iupper(i,:), values, ierr)
  -  end do
  +  ! end do
   
     call HYPRE_StructVectorAssemble(hypre_x, ierr)
   
  
positive.code:   !   hypre_out(2), ierr)
    ! print *, 'final residual norm = ', hypre_out(2)
  
    do i = 0, num_procs-1
      call HYPRE_StructVectorGetBoxValues(hypre_x, &
        ilower(i,:), iupper(i,:), values, ierr)
    end do
  
    do i = 1, nx ! loop over every grid point
      do j = 1, ny
  
negative.code:     end do
    end do
  
    ! do i = 0, num_procs-1
    call HYPRE_StructVectorSetBoxValues(hypre_b, &
        ilower(i,:), iupper(i,:), values, ierr)
    ! end do
  
    call HYPRE_StructVectorAssemble(hypre_b, ierr)
  
  