%Script file from p. 11

X=[2 1 -2 -1;2 -2 2 1];
X(3,:)=ones(1,4);
Y=[-1 1 -1 1];
W=Y/X;

t=linspace(-3,3);
%Seperating line is ax+by+c=0
y=-(W(1)/W(2))*t-(W(3)/W(2));
hold on
plot(X(1,[1,3]),X(2,[1,3]),'go',X(1,[2,4]),X(2,[2,4]),'bo');
plot(t,y,'k');
axis([-3 3 -3 3]);