function [msg, niter] = parallel_protocol(engine, evidence, msg)bnet = bnet_from_engine(engine);N = length(bnet.dag);ns = bnet.node_sizes(:);if ~isempty(engine.filename)  fid = fopen(engine.filename, 'w');  if fid == 0    error(['could not open ' engine.filename ' for writing'])  endelse  fid = 0;endconverged = 0;iter = 1;hidden = find(isemptycell(evidence));bel = cell(1,N);old_bel = cell(1,N);%nodes = mysetdiff(1:N, engine.disconnected_nodes);nodes = find(~engine.disconnected_nodes_bitv);while ~converged & (iter <= engine.max_iter)  % Everybody updates their state in parallel  for n=nodes(:)'    cs_msg = children(engine.msg_dag, n);    %msg{n}.lambda = compute_lambda(n, cs, msg);    msg{n}.lambda = prod_lambda_msgs(n, cs_msg, msg, engine.msg_type);    ps_orig = parents(bnet.dag, n);    msg{n}.pi = CPD_to_pi(bnet.CPD{bnet.equiv_class(n)}, engine.msg_type, n, ps_orig, msg, evidence);  end    changed = 0;  if ~isempty(fid)    fprintf(fid, 'ITERATION %d\n', iter);  end  for n=hidden(:)' % this will not contain any disconnected nodes    old_bel{n} = bel{n};    bel{n}  = compute_bel(engine.msg_type, msg{n}.pi, msg{n}.lambda);    if ~isempty(fid)      fprintf(fid, 'node %d: %s\n', n, bel_to_str(bel{n}, engine.msg_type));    end    if engine.storebel      engine.bel{n,iter} = bel{n};    end    if (iter == 1) | ~approxeq_bel(bel{n}, old_bel{n}, engine.tol, engine.msg_type)      changed = 1;    end  end  converged = ~changed;  if ~converged    % Everybody sends to all their neighbors in parallel    for n=nodes(:)'      % lambda msgs to parents      ps_msg = parents(engine.msg_dag, n);      ps_orig = parents(bnet.dag, n);      for p=ps_msg(:)'	j = engine.child_index{p}(n); % n is p's j'th child	old_msg = msg{p}.lambda_from_child{j}(:);	new_msg = CPD_to_lambda_msg(bnet.CPD{bnet.equiv_class(n)}, engine.msg_type, n, ps_orig, ...				    msg, p, evidence);	lam_msg = convex_combination_msg(old_msg, new_msg, engine.momentum, engine.msg_type);	msg{p}.lambda_from_child{j} = lam_msg;      end       % pi msgs to children      cs_msg = children(engine.msg_dag, n);      for c=cs_msg(:)'	j = engine.parent_index{c}(n); % n is c's j'th parent	old_msg = msg{c}.pi_from_parent{j}(:);	%new_msg = compute_pi_msg(n, cs, msg, c));	new_msg = compute_bel(engine.msg_type, msg{n}.pi, prod_lambda_msgs(n, cs_msg, msg, engine.msg_type, c));	pi_msg = convex_combination_msg(old_msg, new_msg, engine.momentum, engine.msg_type);	msg{c}.pi_from_parent{j} = pi_msg;      end    end    iter = iter + 1;  endendif fid > 0, fclose(fid); end%niter = iter - 1;niter = iter;%%%%%%%%%%function str = bel_to_str(bel, type)switch type case 'd', str = sprintf('%9.4f ', bel(:)'); case 'g', str = sprintf('%9.4f ', bel.mu(:)');end%%%%%%%function a = approxeq_bel(bel1, bel2, tol, type)switch type case 'd', a = approxeq(bel1, bel2, tol); case 'g', a = approxeq(bel1.mu, bel2.mu, tol) & approxeq(bel1.Sigma, bel2.Sigma, tol);end%%%%%%%function msg = convex_combination_msg(old_msg, new_msg, old_weight, type)switch type case 'd', msg = old_weight * old_msg + (1-old_weight)*new_msg; case 'g', msg = new_msg;end