wehub-resource-sync
56 lines
1.4 KiB
Matlab
Executable File
56 lines
1.4 KiB
Matlab
Executable File
function [nodeBel, edgeBel] = mrfExpProp(A, nodePot, edgePot, epoch)
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% Expectation propagation for MRF (Assuming that egdePot is symmetric)
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% Input:
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% A: n x n adjacent matrix of undirected graph, where value is edge index
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% nodePot: k x n node potential
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% edgePot: k x k x m edge potential
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% Output:
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% nodeBel: k x n node belief
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% edgeBel: k x k x m edge belief
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% Written by Mo Chen (sth4nth@gmail.com)
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tol = 0;
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if nargin < 4
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epoch = 50;
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tol = 1e-8;
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end
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nodePot = exp(-nodePot);
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edgePot = exp(-edgePot);
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k = size(nodePot,1);
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m = size(edgePot,3);
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[s,t,e] = find(tril(A));
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mu = ones(k,2*m)/k; % message
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nodeBel = normalize(nodePot,1);
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for iter = 1:epoch
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mu0 = mu;
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for l = 1:m
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i = s(l);
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j = t(l);
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eij = e(l);
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eji = eij+m;
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ep = edgePot(:,:,eij);
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nodeBel(:,j) = nodeBel(:,j)./mu(:,eij);
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mu(:,eij) = normalize(ep*(nodeBel(:,i)./mu(:,eji)));
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nodeBel(:,j) = normalize(nodeBel(:,j).*mu(:,eij));
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nodeBel(:,i) = nodeBel(:,i)./mu(:,eji);
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mu(:,eji) = normalize(ep*(nodeBel(:,j)./mu(:,eij)));
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nodeBel(:,i) = normalize(nodeBel(:,i).*mu(:,eji));
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end
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if max(abs(mu(:)-mu0(:))) < tol; break; end
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end
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edgeBel = zeros(k,k,m);
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for l = 1:m
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eij = e(l);
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eji = eij+m;
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ep = edgePot(:,:,eij);
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nbt = nodeBel(:,t(l))./mu(:,eij);
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nbs = nodeBel(:,s(l))./mu(:,eji);
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eb = (nbt*nbs').*ep;
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edgeBel(:,:,eij) = eb./sum(eb(:));
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end
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