figure
    for i=1:length(t)

        clf;
        hold on
        line([0 cos(phi(i)-pi/2)], [0 sin(phi(i)-pi/2)]);
        plot(cos(phi(i)-pi/2), sin(phi(i)-pi/2), 'ro', 'MarkerSize',25);
        xlim([-1.2 1.2])
        ylim([-1.2 1.2])
        pause(T_end/N)

    end