N=200
x1=5+1.5*randn(N,1);
y1=13+1*randn(N,1);
z1=8+2*randn(N,1);

x2=18+2.2*randn(N,1);
y2=9+3.5*randn(N,1);
z2=11+2*randn(N,1);

x3=12+1*randn(N,1);
y3=3+2.8*randn(N,1);
z3=12+2*randn(N,1);

figure(2)
plot3(x1,y1,z1,'+',x2,y2,z2,'or')
xlabel('length (m)')
ylabel('width (m)')
title('2-class, 3 feature problem- easily separable with a plane for decision boundary')
legend('class 1', 'class 2')
grid on