then, by using neural networking, initial secondary structure is predicted. for each amino acid in the sequence, the neural network is fed with a window of 15 acids. added information is attached, indicating if the window spans the n or c terminus of the chain. this results in a final input layer of 315 input units, divided into 15 groups of 21 units. the network has one hidden layer of 75 units and 3 output nodes (one for each secondary structure element: helix, sheet, coil).