comparison toolboxes/FullBNT-1.0.7/bnt/inference/static/@belprop_inf_engine/private/parallel_protocol.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function [bel, niter] = parallel_protocol(engine, evidence, pot_type, local_kernel, msg)
+
+bnet = bnet_from_engine(engine);
+ns = bnet.node_sizes;
+onodes = find(~isemptycell(evidence));
+
+ndoms = length(engine.gdl.doms);
+prod_of_msg = cell(1, ndoms);
+bel = cell(1, ndoms);
+old_bel = cell(1, ndoms);
+
+converged = 0;
+iter = 1;
+while ~converged & (iter <= engine.max_iter)
+  
+  % each node multiplies all its incoming msgs and computes its local belief
+  old_bel = bel;
+  for i=1:ndoms
+    prod_of_msg{i} = mk_initial_pot(pot_type, engine.gdl.doms{i}, ns, bnet.cnodes, onodes);
+    nbrs = engine.gdl.nbrs{i};
+    for j=nbrs(:)'
+      prod_of_msg{i} = multiply_by_pot(prod_of_msg{i}, msg{j,i});
+    end
+    bel{i} = normalize_pot(multiply_by_pot(local_kernel{i}, prod_of_msg{i}));
+  end
+
+  if ~isempty(engine.fid)
+    for i=1:ndoms
+      tmp = pot_to_marginal(bel{i});
+      %fprintf(engine.fid, '%9.7f ', tmp.T(1));
+      fprintf(engine.fid, '%9.7f ', tmp.U(1));
+    end
+    %fprintf(engine.fid, '  U ');
+    %for i=1:ndoms
+    %  tmp = pot_to_marginal(bel{i});
+    %  fprintf(engine.fid, '%9.7f ', tmp.U(1));
+    %end
+    fprintf(engine.fid, '\n');
+  end
+
+  % converged?
+  if iter==1
+    converged = 0;
+  else
+    converged = 1;
+    for i=1:ndoms
+      if ~approxeq_pot(bel{i}, old_bel{i}, engine.tol)
+	converged = 0;
+	break;
+      end
+    end
+  end
+
+  if ~converged
+    old_msg = msg;
+    % each node sends a msg to each of its neighbors
+    for i=1:ndoms
+      nbrs = engine.gdl.nbrs{i};
+      for j=nbrs(:)'
+	% multiply all incoming msgs except from j
+	temp = prod_of_msg{i};
+	temp = divide_by_pot(temp, old_msg{j,i});
+	% send msg from i to j
+	temp = multiply_by_pot(temp, local_kernel{i});
+	temp2 = marginalize_pot(temp, engine.gdl.sepset{i,j}, engine.maximize);
+	msg{i,j} = normalize_pot(temp2);
+      end
+    end
+  end
+
+  iter = iter + 1;
+end
+
+
+niter = iter-1;
+
+if 0
+for i=1:ndoms
+  prod_of_msg{i} = mk_initial_pot(pot_type, engine.gdl.doms{i}, ns, bnet.cnodes, onodes);
+  nbrs = engine.gdl.nbrs{i};
+  for j=nbrs(:)'
+    prod_of_msg{i} = multiply_by_pot(prod_of_msg{i}, msg{j,i});
+  end
+  bel{i} = normalize_pot(multiply_by_pot(local_kernel{i}, prod_of_msg{i}));
+end
+end