function circle_f1(r);
% CIRCLE_F1 - Function to draw circle x^2+r^2=r^2
alpha = linspace(0,2*pi,100);
x = r*cos(alpha);
y = r*sin(alpha);
plot(x,y);
axis('equal');
xlabel('x')
ylabel('y')
title(['Circle of radius r = ',num2str(r)]) %put a title with the value r.