function marginal = marginal_nodes(engine, nodes, t, add_ev)% MARGINAL_NODES Compute the marginal on the specified query nodes (hmm)% marginal = marginal_nodes(engine, nodes, t, add_ev)%% 't' specifies the time slice of the earliest node in 'nodes'.% 'nodes' cannot span more than 2 time slices.%% Example:% Consider a DBN with 2 nodes per slice.% Then t=2, nodes=[1 3] refers to node 1 in slice 2 and node 1 in slice 3,% i.e., nodes 3 and 5 in the unrolled network,if nargin < 3, t = 1; endif nargin < 4, add_ev = 0; endbnet = bnet_from_engine(engine);ss = length(bnet.intra);if all(nodes <= ss)  bigpot = engine.one_slice_marginal{t};else  bigpot = engine.two_slice_marginal{t};endnodes = nodes + (t-1)*ss;marginal = pot_to_marginal(marginalize_pot(bigpot, nodes, engine.maximize));if add_ev  marginal = add_ev_to_dmarginal(marginal, engine.evidence, engine.node_sizes);end