wolffd@0: function marginal = marginal_nodes(engine, nodes, t)
wolffd@0: % MARGINAL_NODES Compute the marginal on the specified query nodes (pearl_dbn)
wolffd@0: % marginal = marginal_nodes(engine, i, t)
wolffd@0: % returns Pr(X(i,t) | Y(1:T)), where X(i,t) is the i'th node in the t'th slice.
wolffd@0: % If enter_evidence used filtering instead of smoothing, this will return  Pr(X(i,t) | Y(1:t)).
wolffd@0: 
wolffd@0: if nargin < 3, t = 1; end
wolffd@0: assert(length(nodes)==1);
wolffd@0: i = nodes(end);
wolffd@0: if ~myismember(i, engine.onodes)
wolffd@0:   marginal.T = engine.marginal{i,t};
wolffd@0: else
wolffd@0:   marginal.T = 1; % observed
wolffd@0: end
wolffd@0: 
wolffd@0: % we convert the domain to the unrolled numbering system
wolffd@0: % so that update_ess extracts the right evidence.
wolffd@0: marginal.domain = nodes+(t-1)*engine.ss;