wolffd@0: function y = logdet(A)
wolffd@0: % log(det(A)) where A is positive-definite.
wolffd@0: % This is faster and more stable than using log(det(A)).
wolffd@0: 
wolffd@0: %  From Tom Minka's lightspeed toolbox
wolffd@0: 
wolffd@0: U = chol(A);
wolffd@0: y = 2*sum(log(diag(U)));