The method of claim 3 wherein said polynomial expansion has the form: ##EQU5## wherein y represents an output selected from said first and second network output;wherein wi-1 represents the weight value for the ith neuron; wherein xi, xj, xk represent a plurality of network input signals; wherein n is a positive integer; and wherein f1(i) through f6.sub.(i,j,k) are index-generating functions. 8.