1. A pattern recognition system for identifying an input pattern with one of a plurality of prescribed recognizable categories for patterns, comprising: pattern input means for inputting the input pattern to be recognized; feature extraction means for extracting a feature vector from the input pattern inputted by the pattern input means; nonlinear transformation means for applying a nonlinear transformation for each of said prescribed recognizable categories to the feature vector extracted by the feature extraction means to obtain a transformed feature data for the input pattern for each of said prescribed recognizable categories, where the nonlinear transformation for each of said prescribed recognizable categories maps linearly inseparable distributions in a vector space containing the feature vector onto separable distributions; and matching means for comparing the transformed feature data for the input pattern for each of said prescribed recognizable categories with a corresponding reference feature model for each of said prescribed recognizable categories indicating a feature vector distribution for each of said prescribed recognizable categories, for finding a category of the input pattern as that of the reference feature model for one of said prescribed recognizable categories that is closest to the transformed feature data for the input pattern for said one of said prescribed recognizable categories.