Neural Network Toolbox User's Guide

Neuron ModelYou can experiment with a simple neuron and various transfer functions byrunning the demonstration program nnd2n1.Neuron with Vector InputA neuron with a single R-element input vector is shown below. Here theindividual element inputsp 1 , p 2 ,... p Rare multiplied by weightsw 1, 1 , w 1, 2 , ... w 1,Rand the weighted values are fed to the summing junction. Their sum is simplyWp, the dot product of the (single row) matrix W and the vector p.InputNeuron w Vector Inputpp 12p3pRw1,1nfw b1, R1a = f(Wp +b)aWhere...R = number ofelements ininput vectorThe neuron has a bias b, which is summed with the weighted inputs to formthe net input n. This sum, n, is the argument of the transfer function f.This expression can, of course, be written in MATLAB® code as:n = W*p + bn = w 11 , p + 1 w 1, 2 p + 2 ... + w 1, R p + R bHowever, the user will seldom be writing code at this low level, for such code isalready built into functions to define and simulate entire networks.2-5