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

first hg version after svn

+function engine = enter_evidence(engine, evidence)
+
+doms = engine.fg.doms;
+ndoms = length(doms);
+ns = engine.fg.node_sizes;
+obs = find(~isemptycell(evidence));
+cobs = myintersect(obs, engine.fg.cnodes);
+dobs = myintersect(obs, engine.fg.dnodes);
+ns(cobs) = 0;
+ns(dobs) = 1;
+
+% prime each local kernel with evidence (if any)
+local_kernel = cell(1, ndoms);
+for i=1:length(engine.fg.kernels_of_type)
+  u = engine.fg.kernels_of_type{i};
+  local_kernel(u) = kernel_to_dpots(engine.fg.kernels{i}, evidence, engine.fg.domains_of_type{i});
+end
+  
+% initialise all msgs to 1s
+nedges = engine.fg.nedges;
+msg = cell(1, nedges);
+for i=1:nedges
+  msg{i} = dpot(engine.fg.sepset{i}, ns(engine.fg.sepset{i}));
+end
+
+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
+  for i=1:ndoms
+    prod_of_msg{i} = dpot(doms{i}, ns(doms{i}));
+    nbrs = engine.fg.nbrs{i};
+    for j=1:length(nbrs)
+      ndx = engine.fg.edge_ndx(j,i);
+      prod_of_msg{i} = multiply_by_pot(prod_of_msg{i}, msg{ndx});
+    end
+  end
+  old_msg = msg;
+  
+  % each node computes its local belief
+  for i=1:ndoms
+    bel{i} = normalize_pot(multiply_pots(prod_of_msg{i}, local_kernel{i}));
+  end
+
+  % converged?
+  converged = 1;
+  for i=1:ndoms
+    if ~approxeq(bel{i}, old_bel{i}, engine.tol)
+      converged = 0;
+      break;
+    end
+  end
+
+  if ~converged
+    % each node sends a msg to each of its neighbors
+    for i=1:ndoms
+      nbrs = engine.fg.nbrs{i};
+      for j=1:length(nbrs)
+	% multiply all incoming msgs except from j
+	temp = prod_of_msg{i};
+	ndx = engine.fg.edge_ndx(j,i);
+	temp = divide_by_pot(temp, old_msg{ndx});
+	% send msg from i to j
+	temp = multiply_by_pot(temp, local_kernel{i});
+	ndx = engine.fg.edge_ndx(i,j);
+	msg{ndx} = normalize_pot(marginalize_pot(temp, engine.fg.sepset{ndx}));
+      end
+    end
+  end
+
+  iter = iter + 1;
+end
+
+  
+engine.marginal = bel;