public void initiate_recv_bottom()
 {
     // int rank = comm.Rank;
     // Console.Write(rank + ": z - initiate_recv_top :");
     //if (Shift_z_top.HandleLeft != null)
     //		requestList.Remove(Shift_z_top.HandleLeft);
     if (Shift_z_top.HandleRight != null)
     {
         requestList.Remove(Shift_z_top.HandleRight);
     }
     Shift_z_top.initiate_recv();
     //requestList.Add(Shift_z_top.HandleLeft);
     requestList.Add(Shift_z_top.HandleRight);
 }
 public void shift_z_right()
 {
     Shift_z_top.go();
 }