Daniel@0: function [engine, loglik] = enter_evidence(engine, evidence, varargin)
Daniel@0: % ENTER_EVIDENCE Add the specified evidence to the network (hmm)
Daniel@0: % [engine, loglik] = enter_evidence(engine, evidence, ...)
Daniel@0: %
Daniel@0: % evidence{i,t} = [] if if X(i,t) is hidden, and otherwise contains its observed value (scalar or column vector)
Daniel@0: %
Daniel@0: % The following optional arguments can be specified in the form of name/value pairs:
Daniel@0: % [default value in brackets]
Daniel@0: %
Daniel@0: % maximize - if 1, does max-product (not yet supported), else sum-product [0]
Daniel@0: % filter   - if 1, does filtering, else smoothing [0]
Daniel@0: % oneslice - 1 means only compute marginals on nodes within a single slice [0]
Daniel@0: %
Daniel@0: % e.g., engine = enter_evidence(engine, ev, 'maximize', 1)
Daniel@0: 
Daniel@0: maximize = 0;
Daniel@0: filter = 0;
Daniel@0: oneslice = 0;
Daniel@0: 
Daniel@0: % parse optional params
Daniel@0: args = varargin;
Daniel@0: nargs = length(args);
Daniel@0: if nargs > 0
Daniel@0:   for i=1:2:nargs
Daniel@0:     switch args{i},
Daniel@0:      case 'maximize', maximize = args{i+1}; 
Daniel@0:      case 'filter',  filter = args{i+1}; 
Daniel@0:      case 'oneslice', oneslice = args{i+1};
Daniel@0:      otherwise,  
Daniel@0:       error(['invalid argument name ' args{i}]);       
Daniel@0:     end
Daniel@0:   end
Daniel@0: end
Daniel@0: 
Daniel@0: [ss T] = size(evidence);
Daniel@0: engine.maximize = maximize;
Daniel@0: engine.evidence = evidence;
Daniel@0: bnet = bnet_from_engine(engine);
Daniel@0: engine.node_sizes = repmat(bnet.node_sizes_slice(:), [1 T]);
Daniel@0: 
Daniel@0: obs_bitv = ~isemptycell(evidence(:));
Daniel@0: bitv = reshape(obs_bitv, ss, T);
Daniel@0: for t=1:T
Daniel@0:   onodes = find(bitv(:,t));
Daniel@0:   if ~isequal(onodes, bnet.observed(:))
Daniel@0:     error(['dbn was created assuming observed nodes per slice were '...
Daniel@0: 	   num2str(bnet.observed(:)')  ' but the evidence in slice ' num2str(t) ...
Daniel@0: 	   ' has observed nodes ' num2str(onodes(:)')]);
Daniel@0:   end
Daniel@0: end
Daniel@0: 
Daniel@0: obslik = mk_hmm_obs_lik_matrix(engine, evidence);
Daniel@0: 
Daniel@0: %[alpha, beta, gamma, loglik, xi] = fwdback(engine.startprob, engine.transprob, obslik, ...
Daniel@0: [alpha, beta, gamma, loglik, xi] = fwdback_twoslice(engine, engine.startprob,...
Daniel@0:                                                     engine.transprob, obslik, ...
Daniel@0:                                                     'maximize', maximize, 'fwd_only', filter, ...
Daniel@0:                                                     'compute_xi', ~oneslice);
Daniel@0: 
Daniel@0: engine.one_slice_marginal = gamma; % gamma(:,t) for t=1:T
Daniel@0: if ~oneslice
Daniel@0:   Q = size(gamma,1);
Daniel@0:   engine.two_slice_marginal = reshape(xi, [Q*Q T-1]); % xi(:,t) for t=1:T-1
Daniel@0: end