function [engine, ll, niter] = enter_evidence(engine, evidence, varargin)% ENTER_EVIDENCE Propagate evidence using belief propagation% [engine, ll, niter] = enter_evidence(engine, evidence, ...)%% The log-likelihood is not computed; ll = 0.% niter contains the number of iterations used (if engine.protocol = 'parallel')%% The following optional arguments can be specified in the form of name/value pairs:% [default value in brackets]%% maximize - 1 means use max-product, 0 means use sum-product [0]% exclude  - list of nodes whose potential will not be included in the joint [ [] ]%% e.g., engine = enter_evidence(engine, ev, 'maximize', 1)ll = 0;exclude = [];maximize = 0;if nargin >= 3  args = varargin;  nargs = length(args);  for i=1:2:nargs    switch args{i},     case 'exclude', exclude = args{i+1};     case 'maximize', maximize = args{i+1};     otherwise,      error(['invalid argument name ' args{i}]);    end  endendengine.maximize = maximize;if ~isempty(engine.filename)  engine.fid = fopen(engine.filename, 'w');  if engine.fid == 0    error(['can''t open ' engine.filename]);  endelse  engine.fid = [];endgdl = engine.gdl;bnet = bnet_from_engine(engine);ndoms = length(gdl.doms);ns = bnet.node_sizes;onodes = find(~isemptycell(evidence));pot_type = determine_pot_type(bnet, onodes);% prime each local kernel with evidence (if any)local_kernel = cell(1, ndoms);for i=1:ndoms  if myismember(i, exclude)    local_kernel{i} =  mk_initial_pot(pot_type, gdl.doms{i}, ns, bnet.cnodes, onodes);  else    e = bnet.equiv_class(i);    local_kernel{i} =  convert_to_pot(bnet.CPD{e}, pot_type, gdl.doms{i}(:), evidence);  endend  % initialise all msgs to 1smsg = cell(ndoms, ndoms);for i=1:ndoms  nbrs = gdl.nbrs{i};  for j=nbrs(:)'    dom = gdl.sepset{i,j};    msg{i,j} = mk_initial_pot(pot_type, dom, ns, bnet.cnodes, onodes);  endendswitch engine.protocol case 'parallel',    [engine.marginal_domains, niter] = parallel_protocol(engine, evidence, pot_type, local_kernel, msg); case 'tree',  engine.marginal_domains = serial_protocol(engine, evidence, pot_type, local_kernel, msg);  niter = 1;endengine.niter = niter;%fprintf('just finished %d iterations of belprop\n', niter);if ~isempty(engine.filename)  fclose(engine.fid);end