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1 function pot = CPD_to_scgpot(CPD, domain, ns, cnodes, evidence)
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2 % CPD_TO_CGPOT Convert a Gaussian CPD to a CG potential, incorporating any evidence
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3 % pot = CPD_to_cgpot(CPD, domain, ns, cnodes, evidence)
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4
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5 self = CPD.self;
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6 dnodes = mysetdiff(1:length(ns), cnodes);
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7 odom = domain(~isemptycell(evidence(domain)));
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8 cdom = myintersect(cnodes, domain);
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9 cheaddom = myintersect(self, domain);
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10 ctaildom = mysetdiff(cdom,cheaddom);
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11 ddom = myintersect(dnodes, domain);
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12 cobs = myintersect(cdom, odom);
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13 dobs = myintersect(ddom, odom);
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14 ens = ns; % effective node size
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15 ens(cobs) = 0;
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16 ens(dobs) = 1;
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17
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18 % Extract the params compatible with the observations (if any) on the discrete parents (if any)
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19 % parents are all but the last domain element
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20 ps = domain(1:end-1);
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21 dps = myintersect(ps, ddom);
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22 dops = myintersect(dps, odom);
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23
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24 map = find_equiv_posns(dops, dps);
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25 dpvals = cat(1, evidence{dops});
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26 index = mk_multi_index(length(dps), map, dpvals);
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27
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28 dpsize = prod(ens(dps));
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29 cpsize = size(CPD.weights(:,:,1), 2); % cts parents size
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30 ss = size(CPD.mean, 1); % self size
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31 % the reshape acts like a squeeze
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32 m = reshape(CPD.mean(:, index{:}), [ss dpsize]);
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33 C = reshape(CPD.cov(:, :, index{:}), [ss ss dpsize]);
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34 W = reshape(CPD.weights(:, :, index{:}), [ss cpsize dpsize]);
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35
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36
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37 % Convert each conditional Gaussian to a canonical potential
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38 pot = cell(1, dpsize);
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39 for i=1:dpsize
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40 %pot{i} = linear_gaussian_to_scgcpot(m(:,i), C(:,:,i), W(:,:,i), cdom, ns, cnodes, evidence);
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41 pot{i} = scgcpot(ss, cpsize, 1, m(:,i), W(:,:,i), C(:,:,i));
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42 end
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43
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44 pot = scgpot(ddom, cheaddom, ctaildom, ens, pot);
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45
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46
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47 function pot = linear_gaussian_to_scgcpot(mu, Sigma, W, domain, ns, cnodes, evidence)
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48 % LINEAR_GAUSSIAN_TO_CPOT Convert a linear Gaussian CPD to a stable conditional potential element.
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49 % pot = linear_gaussian_to_cpot(mu, Sigma, W, domain, ns, cnodes, evidence)
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50
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51 p = 1;
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52 A = mu;
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53 B = W;
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54 C = Sigma;
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55 ns(odom) = 0;
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56 %pot = scgcpot(, ns(domain), p, A, B, C);
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57
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58
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