wehub-resource-sync
17 lines
522 B
Matlab
Executable File
17 lines
522 B
Matlab
Executable File
function y = logDirichlet(X, a)
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% Compute log pdf of a Dirichlet distribution.
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% Input:
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% X: d x n data matrix, each column sums to one (sum(X,1)==ones(1,n) && X>=0)
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% a: d x k parameter of Dirichlet
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% y: k x n probability density
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% Output:
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% y: k x n probability density in logrithm scale y=log p(x)
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% Written by Mo Chen (sth4nth@gmail.com).
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X = bsxfun(@times,X,1./sum(X,1));
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if size(a,1) == 1
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a = repmat(a,size(X,1),1);
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end
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c = gammaln(sum(a,1))-sum(gammaln(a),1);
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g = (a-1)'*log(X);
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y = bsxfun(@plus,g,c');
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