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