comparison toolboxes/FullBNT-1.0.7/bnt/inference/static/@belprop_inf_engine/Old/enter_evidence1.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function engine = enter_evidence(engine, evidence)
+
+doms = engine.fgraph.doms;
+ndoms = length(doms);
+ns = engine.fgraph.node_sizes;
+obs = find(~isemptycell(evidence));
+cobs = myintersect(obs, engine.fgraph.cnodes);
+dobs = myintersect(obs, engine.fgraph.dnodes);
+ns(cobs) = 0;
+ns(dobs) = 1;
+
+% recompute the weight of each domain now that we know what nodes are observed
+for i=1:ndoms
+  engine.dom_weight(i) = prod(ns(engine.fgraph.doms{i}));
+end
+
+% prime each local kernel with evidence (if any)
+local_kernel = cell(1, ndoms);
+for i=1:length(engine.fgraph.kernels_of_type)
+  u = engine.fgraph.kernels_of_type{i};
+  local_kernel(u) = kernel_to_dpots(engine.fgraph.kernels{i}, evidence, engine.fgraph.domains_of_type{i});
+end
+  
+% initialise all msgs to 1s
+msg = cell(ndoms, ndoms);
+for i=1:ndoms
+  nbrs = engine.fgraph.nbrs{i};
+  for j=nbrs(:)'
+    dom = engine.fgraph.sepset{i,j};
+    msg{i,j} = dpot(dom, ns(dom));
+  end
+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.fgraph.nbrs{i};
+    for j=nbrs(:)'
+      prod_of_msg{i} = multiply_by_pot(prod_of_msg{i}, msg{j,i});
+    end
+  end
+  
+  % each node computes its local belief
+  old_bel = bel;
+  for i=1:ndoms
+    bel{i} = normalize_pot(multiply_pots(prod_of_msg{i}, local_kernel{i}));
+  end
+
+  % converged?
+  if iter==1
+    converged = 0;
+  else
+    converged = 1;
+    for i=1:ndoms
+      belT = get_params(bel{i}, 'table');
+      old_belT = get_params(old_bel{i}, 'table');
+      if ~approxeq(belT, old_belT, 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.fgraph.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});
+	msg{i,j} = normalize_pot(marginalize_pot(temp, engine.fgraph.sepset{i,j}));
+      end
+    end
+  end
+
+  iter = iter + 1
+end
+
+engine.marginal_domains = bel;
+%for i=1:ndoms  
+  %engine.marginal_domains{i} = get_params(bel{i}, 'table');
+%end