mu1x = 8;
mu1y = 9;
rad1 = 1;
x1 = [0:100]*2/100 - 1;
x1 = rad1*x1 + mu1x;
y1a = mu1y + sqrt(rad1^2-(x1-mu1x).^2);
y1b = mu1y - sqrt(rad1^2-(x1-mu1x).^2);

mu2x = 0;
mu2y = 9;
rad2 = 4;
x2 = [0:100]*2/100 - 1;
x2 = rad2*x2 + mu2x;
y2a = mu2y + sqrt(rad2^2-(x2-mu2x).^2);
y2b = mu2y - sqrt(rad2^2-(x2-mu2x).^2);

hold off;
plot(x1,y1a,'r-');
hold on;
plot(x1,y1b,'r-');

plot(x2,y2a,'b-');
plot(x2,y2b,'b-');

title('One sigma ellipses');
xlabel('x_1');
ylabel('x_2');

