function L = log_student_pdf(X, mu, lambda, alpha)% LOG_STUDENT_PDF Evaluate the log of the multivariate student-t distribution at a point% L = log_student_pdf(X, mu, lambda, alpha)%% Each column of X is evaluated.% See Bernardo and Smith p435.k = length(mu);assert(size(X,1) == k);[k N] = size(X);logc = gammaln(0.5*(alpha+k)) - gammaln(0.5*alpha) - (k/2)*log(alpha*pi) + 0.5*log(det(lambda));middle = (1 + (1/alpha)*(X-mu)'*lambda*(X-mu)); % scalar versionL = logc - ((alpha+k)/2)*log(middle);