1. An analog content addressable memory system for determining the degree of similarity between an unknown pattern and a plurality of reference patterns, said system comprising: input lines for presenting continuously variable values representing unknown patterns and reference patterns to said system, each of the patterns corresponding to a point in N-dimensional space; memory means for storing said values representing the reference patterns; and processing means for determining the distance between said point representing the unknown pattern and each of said points representing the reference patterns, said distance being inversely proportional to the degree of similarity between the unknown pattern and said reference patterns, said distance D being determined by the formula ##EQU5## where IN(J) are the values representing the unknown pattern, and W(I,J) are the values representing the stored patterns, J varying from 1 to N and I varying from 1 to M.