In general neural networks are simply mathematical techniques designed to accomplish a variety of tasks. Neural networks can be configured in various arrangements to perform a range of tasks including pattern recognition, data mining, classification, and process modeling. The later is the primary interest in this context and although the types and topologies of neural networks (NN) vary greatly in the field, by far the most commonly used type of neural network, particularly in process control, is the feed-forward, back-propagation NN.