% This program illustrates a critical limitation of single-layer neural
%networks. The network is used to solve the XOR problem, which is not
%linearly separable.

clear all
clc

X = [0 0 1;
     0 1 1;
     1 0 1;
     1 1 1];
D = [0; 1; 1; 0];

W = 2*rand(1, 3) - 1;

% Training:
max_epoch = 40000;
for epoch = 1:max_epoch
    W = DeltaSGD(W, X, D);
end

%Inference:
N = size(X,1);
y = zeros(N,1);
for k = 1:N
    x = X(k, :)';
    v = W*x;
    y(k) = Sigmoid(v);
end

disp('Results:');
disp('   [desired   neuron_output]');
disp([D y]);