function marginal = marginal_nodes(engine, nodes, t, add_ev)% MARGINAL_NODES Compute the joint distribution on a set of nodes (filter_engine)% function marginal = marginal_nodes(engine, nodes, t, add_ev)if nargin < 4, add_ev = 0; endif t ~= engine.t  error('mixed up time stamps')endmarginal = marginal_nodes(engine.tbn_engine, engine.b, nodes, t, add_ev);