anchor.diff:    integer,   intent(in)  :: iupper(0:num_procs-1,2)
     integer,   intent(in)  :: num_procs
     integer,   intent(in)  :: myid
  +  integer,   intent(in)  :: nx
  +  integer,   intent(in)  :: ny
     integer,   intent(out)  :: ierr
   
   #ifdef useExtSolver
  
positive.code: ! ---------------------------------------------------------------------------
  
  subroutine create_Hypre_grid(MPI_COMM_WORLD, hypre_grid, ilower, iupper, &
            num_procs, myid, ierr)
    implicit none
  
    integer,   intent(in)  :: MPI_COMM_WORLD
  
negative.code:   !do i = 0, num_procs-1
    call HYPRE_StructGridSetExtents(hypre_grid, ilower(myid,:),iupper(myid,:), ierr)
    !end do
  
    call HYPRE_StructGridSetPeriodic(hypre_grid, [nx, ny], ierr)
  
    call HYPRE_StructGridAssemble(hypre_grid, ierr)
  #endif
  