1. A system for processing exogenous feature vectors to recognize patterns, each exogenous feature vector being a feature vector input to said system, said system comprising at least one processing unit that comprises (a) storage means for storing at least one expansion correlation matrix; (b) expansion means, responsive to a feature subvector input to said processing unit, for generating at least one orthogonal expansion of a subvector of said feature subvector; and (c) estimation means for using said at least one expansion correlation matrix and said at least one orthogonal expansion to produce a representative of a probability distribution of a label of said feature subvector.