comparison toolboxes/FullBNT-1.0.7/bnt/inference/static/@cond_gauss_inf_engine/marginal_nodes.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function marginal = marginal_nodes(engine, query, add_ev)
+% MARGINAL_NODES Compute the marginal on the specified query nodes (cond_gauss)
+% marginal = marginal_nodes(engine, query, add_ev)
+%
+% 'query' must be a singleton set
+% add_ev is an optional argument; if 1, we will "inflate" the marginal of observed nodes
+% to their original size, adding 0s to the positions which contradict the evidence
+
+if nargin < 3, add_ev = 0; end
+
+if length(query) ~= 1
+  error('cond_gauss_inf_engine can only handle marginal queries on single nodes')
+end
+j = query;
+bnet = bnet_from_engine(engine);
+
+if myismember(j, bnet.cnodes)
+  if ~myismember(j, engine.onodes)
+    [m, C] = collapse_mog(engine.mu{j}, engine.Sigma{j}, engine.T);    
+    marginal.mu = m;
+    marginal.Sigma = C;
+    marginal.T = 1.0; % single mixture component
+  else
+    marginal.mu = engine.evidence{j};
+    k = bnet.node_sizes(j);
+    marginal.Sigma = zeros(k,k);
+    marginal.T = 1.0; % since P(E|E)=1
+  end
+else
+  marginal = pot_to_marginal(marginalize_pot(engine.joint_dmarginal, j));
+  if add_ev
+    marginal = add_ev_to_dmarginal(marginal, engine.evidence, bnet.node_sizes);
+  end
+end
+
+marginal.domain = query;