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1 function [bel, niter] = parallel_protocol(engine, evidence, pot_type, local_kernel, msg)
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2
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3 bnet = bnet_from_engine(engine);
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4 ns = bnet.node_sizes;
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5 onodes = find(~isemptycell(evidence));
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6
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7 ndoms = length(engine.gdl.doms);
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8 prod_of_msg = cell(1, ndoms);
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9 bel = cell(1, ndoms);
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10 old_bel = cell(1, ndoms);
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11
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12 converged = 0;
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13 iter = 1;
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14 while ~converged & (iter <= engine.max_iter)
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15
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16 % each node multiplies all its incoming msgs and computes its local belief
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17 old_bel = bel;
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18 for i=1:ndoms
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19 prod_of_msg{i} = mk_initial_pot(pot_type, engine.gdl.doms{i}, ns, bnet.cnodes, onodes);
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20 nbrs = engine.gdl.nbrs{i};
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21 for j=nbrs(:)'
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22 prod_of_msg{i} = multiply_by_pot(prod_of_msg{i}, msg{j,i});
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23 end
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24 bel{i} = normalize_pot(multiply_by_pot(local_kernel{i}, prod_of_msg{i}));
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25 end
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26
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27 if ~isempty(engine.fid)
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28 for i=1:ndoms
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29 tmp = pot_to_marginal(bel{i});
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30 %fprintf(engine.fid, '%9.7f ', tmp.T(1));
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31 fprintf(engine.fid, '%9.7f ', tmp.U(1));
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32 end
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33 %fprintf(engine.fid, ' U ');
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34 %for i=1:ndoms
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35 % tmp = pot_to_marginal(bel{i});
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36 % fprintf(engine.fid, '%9.7f ', tmp.U(1));
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37 %end
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38 fprintf(engine.fid, '\n');
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39 end
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40
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41 % converged?
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42 if iter==1
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43 converged = 0;
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44 else
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45 converged = 1;
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46 for i=1:ndoms
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47 if ~approxeq_pot(bel{i}, old_bel{i}, engine.tol)
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48 converged = 0;
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49 break;
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50 end
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51 end
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52 end
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53
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54 if ~converged
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55 old_msg = msg;
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56 % each node sends a msg to each of its neighbors
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57 for i=1:ndoms
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58 nbrs = engine.gdl.nbrs{i};
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59 for j=nbrs(:)'
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60 % multiply all incoming msgs except from j
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61 temp = prod_of_msg{i};
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62 temp = divide_by_pot(temp, old_msg{j,i});
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63 % send msg from i to j
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64 temp = multiply_by_pot(temp, local_kernel{i});
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65 temp2 = marginalize_pot(temp, engine.gdl.sepset{i,j}, engine.maximize);
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66 msg{i,j} = normalize_pot(temp2);
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67 end
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68 end
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69 end
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70
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71 iter = iter + 1;
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72 end
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73
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74
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75 niter = iter-1;
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76
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77 if 0
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78 for i=1:ndoms
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79 prod_of_msg{i} = mk_initial_pot(pot_type, engine.gdl.doms{i}, ns, bnet.cnodes, onodes);
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80 nbrs = engine.gdl.nbrs{i};
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81 for j=nbrs(:)'
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82 prod_of_msg{i} = multiply_by_pot(prod_of_msg{i}, msg{j,i});
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83 end
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84 bel{i} = normalize_pot(multiply_by_pot(local_kernel{i}, prod_of_msg{i}));
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85 end
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86 end
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