Machine Learning.
http://deeplearning.stanford.edu/wiki/index.php/Sparse_Coding:_Autoencoder_InterpretationSparse%20Coding:%20Autoencoder%20Interpretation%20-%20Ufldl.%20(2018).%20Deeplearning.stanford.edu.%20Retrieved%206%20September%202018,%20from%20http://deeplearning.stanford.edu/wiki/index.php/Sparse_Coding:_Au