function marginal = marginal_family(engine, i, t, add_ev)% MARGINAL_FAMILY Compute the marginal on the specified family (hmm)% marginal = marginal_family(engine, i, t, add_ev)if nargin < 3, t = 1; endif nargin < 4, add_ev = 0; endns = engine.eff_node_sizes(:);ss = engine.slice_size;if t==1 | ~engine.persist_bitv(i)  bigT = engine.one_slice_marginal(:,t);  ps = engine.parents{i};  dom = [ps i] + (t-1)*ss;  bigdom = 1:ss;  bigsz = ns(bigdom);  bigdom = bigdom + (t-1)*ss;else % some parents are in previous slice  bigT = engine.two_slice_marginal(:,t-1); % t-1 and t  ps = engine.parents{i+ss};  dom = [ps i+ss] + (t-2)*ss;   bigdom = 1:(2*ss); % domain of xi(:,:,t)  bigsz = ns(bigdom);  bigdom = bigdom + (t-2)*ss;endmarginal.domain = dom;marginal.T = marg_table(bigT, bigdom, bigsz, dom, engine.maximize); marginal.mu = []; marginal.Sigma = [];if add_ev  marginal = add_ev_to_dmarginal(marginal, engine.evidence, engine.node_sizes);end