Machine Learning, Probabilistic Modelling, Rbm, Deep Belief Network.
example. https://cs.nyu.edu/~roweis/lle/faces.html Density Estimation for a Gaussian mixture. http://scikit-learn.org/stable/auto_examples/mixture/plot_gmm_pdf.html In modelling complex and high dimension data distribution, a popular probabilistic approach is using the mixture model, a typical