% [t, z] = ode45(@sys1, [0, 3], [4, -1]);
% plot(z(:,1), z(:,2))
% hold on
% [t, z] = ode45(@sys1, [0, -2], [4, -1]);
% plot(z(:,1), z(:,2), 'r')
% axis([-10, 10, -10, 10])
%
% clear
%
% plot([-10, 10], [0, 0], 'k')
% hold on
% plot([0, 0], [-10, 10])
% [x0, y0] = ginput(1);
%
% while true
%
%     [t, z] = ode45(@sys1, [0, 3], [x0, y0]);
%     plot(z(:,1), z(:,2), 'b')
%     [t, z] = ode45(@sys1, [0, -3], [x0, y0]);
%     plot(z(:,1), z(:,2), 'r')
%     [x0, y0] = ginput(1);
% end
%
% clear

[t, z] = ode45(@sys1, [0, 6], [4, 3]);
for k=1 : length(z) - 6
    plot(z(k:k+6, 1), z(k:k+6, 2), 'b')
    hold on
    plot(z(k+6, 1), z(k+6, 2), 'o')
    axis([-12, 12, -12, 12])
    M(k) = getframe;
    hold off
end
movie(M, 4, 60)