public void initiate_recv_south()
 {
     //int rank = comm.Rank;
     //Console.Write(rank + ": y - initiate_recv_north :");
     //if (Shift_y_north.HandleLeft != null)
     //		requestList.Remove(Shift_y_north.HandleLeft);
     if (Shift_y_north.HandleRight != null)
     {
         requestList.Remove(Shift_y_north.HandleRight);
     }
     Shift_y_north.initiate_recv();
     //requestList.Add(Shift_y_north.HandleLeft);
     requestList.Add(Shift_y_north.HandleRight);
 }
 public void shift_y_left()
 {
     Shift_y_north.go();
 }