plt.subplot(3, 1, 1)
l1, = plt.plot(t, v)
plt.subplot(3, 1, 2)
l2, = plt.plot(t, r)
plt.subplot(3, 1, 3)
u = np.arange(0, 10, .1)
l3, = plt.plot(u, r_inf(u))
l4, = plt.plot(u, tau_r(u))
def update(val):
    #do some calculation and get some new data
    l1.set_ydata(_v)
    plt.gca().relim()
    plt.gca().autoscale_view()
    l2.set_ydata(_r)
    l3.set_ydata(r_inf(u))
    l4.set_ydata(tau_r(u))
    fig.canvas.draw_idle()
plt.show()