function sync_start(comm,starter_rank,delay)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This function tries to get all processes in a
% MatlabMPI communicatior to wait and start at the same.
% Assumes clocks across the machines are synchronized
% to the level you want.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% MatlabMPI
% Dr. Jeremy Kepner
% MIT Lincoln Laboratory
% kepner@ll.mit.edu
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  % Get size and rank.
  comm_size = MPI_Comm_size(comm);
  my_rank = MPI_Comm_rank(comm);

  if(comm_size < 2)
    disp('Too few processors (need at least 2) to synchronize');
    return;
  end


  % Create a unique tag id for the synch message.
  synch_tag = 99999;

  if (my_rank == starter_rank)
    % Get a zero clock.
    zero_clock = clock;

    % Get current time
    current_time = etime(clock,zero_clock);

    % Compute synchronized start time.
    start_time = current_time + delay;

    % Broadcast to everyone else.
    MPI_Bcast( starter_rank, synch_tag, comm, zero_clock, start_time );

    % Get current time again.
    current_time = etime(clock,zero_clock);

    % Compute pause time.
    pause_time = start_time - current_time

    % Pause.
%    pause(pause_time);

  else

    % Receive time from starter.
    [zero_clock start_time] = MPI_Recv( starter_rank, synch_tag, comm );

    % Get current time again.
    current_time = etime(clock,zero_clock);

    % Compute pause time.
    pause_time = start_time - current_time

    % Pause.
%    pause(pause_time);

  end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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