x(:,1) = unifrnd(0,repmat(1,1000,1));
x(:,2) = x(:,1) + unifrnd(0,repmat(1,1000,1));

m = mean(x,1)

hold on;
scatter(x(:,1),x(:,2));


[COEFF, SCORE, latent] = princomp(x);

COEFF
latent

circle1 = scircle1(0,0,1);
D = [sqrt(latent(1)) 0; 0 sqrt(latent(2))];
circle = (circle1*D)*COEFF';
circle = circle + repmat(m,size(circle,1),1);
plot(circle(:,1),circle(:,2),'r');

figure;

hold on;
scatter(SCORE(:,1),SCORE(:,2));
circle = (circle1*D);
plot(circle(:,1),circle(:,2),'r');