1. A triple matrix product processor for optically multiplying three matrices U, G, and V, comprising: a matrix-vector processor for sequentially multiplying each column of a M.times.N matrix G by at least a portion of P.times.M matrix U, wherein at a given instant the l.sup.th column of G is multiplied by the at least a portion of matrix U producing at least the il.sup.th element of an intermediate result; an outer product processor for multiplying said at least the il.sup.th element of said intermediate result with the l.sup.th row of an N.times.Q matrix V producing at least a portion of a P.times.Q outer product matrix in a first plane; and a time-integrating optical detector array for summing the light impinging on said first plane from said outer product processor to produce all or a desired portion of a P.times.Q triple matrix product after all of the N columns of said matrix G and all of the N rows of said matrix V have been cycled through said processors.