function [engine, ll] = enter_evidence(engine, evidence, nsamples)% ENTER_EVIDENCE Add the specified evidence to the network (likelihood_weighting)% [engine, ll] = enter_evidence(engine, evidence, nsamples)% evidence{i} = [] if if X(i) is hidden, and otherwise contains its observed value (scalar or column vector)%% If nsamples is not specified, the value specified when the engine was created will be used.% ll (log-likelihood) is set to [].ll = [];if nargin < 3, nsamples = engine.nsamples; endbnet = bnet_from_engine(engine);N = length(bnet.dag);samples = cell(nsamples, N);weights = zeros(1, nsamples);ns = bnet.node_sizes;original_evidence = evidence;observed = ~isemptycell(original_evidence);for s=1:nsamples  evidence = original_evidence(:); % must be a column vector  w = 1;  for i=1:N    ps = parents(bnet.dag, i);    e = bnet.equiv_class(i);    if observed(i)      p = exp(log_prob_node(bnet.CPD{e}, evidence(i), evidence(ps)));      w = w * p;    else      x = sample_node(bnet.CPD{e}, evidence(ps));      evidence{i} = x;    end  end  samples(s,:) = evidence;  weights(s) = w;end                 engine.samples = samples;engine.weights = weights;