pendulum_ode45:
  Test pendulum_ode using ode45().
  Number of steps taken was N = 344
  Graphics saved in "pendulum_ode45_theta.png"
  Graphics saved in "pendulum_ode45_thetadot.png"
  Graphics saved in "pendulum_ode45_energy.png"
  h(1) = 5.37345, h(n+1) = 5.35411