samer@4: function y = logdet(A)
samer@4: % logdet - logdet(X)=log(det(X)) where A is positive-definite and Hermitian.
samer@4: %
samer@4: % logdet :: [[N,N]] -> nonneg.
samer@4: %
samer@4: % This is faster and more stable than using log(det(A)).
samer@4: % Samer: Use LOGABSDET for general matrices.
samer@4: 
samer@4: %  From Tom Minka's lightspeed toolbox
samer@4: 
samer@4: [U,p] = chol(A);
samer@4: if p>0, y=-inf;
samer@4: else y = 2*sum(log(full(diag(U))));
samer@4: end