1. An optical system for performing matrix manipulations, comprising: a source means for producing a plurality of light beams to illuminate a plurality of locations, the intensity of each beam representative of a predetermined value in an N.times.1 column vector, Q; an optically transmissive mask disposed to be illuminated by said source means and including a plurality of elements corresponding to said plurality of locations, said elements disposed in a two-dimensional mask matrix having M+1 rows and N columns, wherein each said element has information defined by its degree of optical transmittance, and each element in each row of M rows of said mask matrix is representative of the sum of a predetermined value in a known M.times.N matrix and a scalar constant, c, and each element of the remaining row of said mask matrix is representative of said scalar constant, c; and photodetection means positioned to receive light transmitted through said mask for determining the intensity of light received at its position, and for providing one or more first signals representative of a function of said vector Q and said known matrix and a second signal representative of a function of said vector Q and said scalar constant, c.