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function L = log_prior(CPD)
% LOG_PRIOR Return log P(theta) for a tabular CPD
% L = log_prior(CPD)
switch CPD.prior_type
case 'none',
L = 0;
case 'dirichlet',
D = CPD.dirichlet(:);
L = sum(log(D + (D==0)));
case 'entropic',
% log-prior = log exp(-H(theta)) = sum_i theta_i log (theta_i)
fam_sz = CPD.sizes;
psz = prod(fam_sz(1:end-1));
ssz = fam_sz(end);
C = reshape(CPD.CPT, psz, ssz);
L = sum(sum(C .* log(C + (C==0))));
end
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