neuroscience result used to try to explain you know computations in the brain or something like that right and this is how the atom works is an unsupervised learning algorithm so the way where else is you feed it a set of m images X 1 X 2 up to X M so each input example is and let's say an N by n matrix yo quicker like a 14 by 14 image patch what's fast coding does is it learns the dictionary of basis functions Phi 1 Phi 2 up to 5 K such that each of your training images X subject to the constraint that the a J's are mostly 0