We will finish the chapter with a more complex example that illustrates the power that matplotlib gives us. We will create an animation of a forced pendulum, a well-known and much studied example of a dynamic system exhibiting deterministic chaos.

Since this section involves more sophisticated code, we will refrain from using pylab and adopt the generally recommended way of importing modules. This makes the code easier to export to a script if we so wish. We also give samples of some of the object-oriented features of matplotlib.

The process of animating a pendulum (or any physical process) is actually very simple: we compute the position of the pendulum at a finite number of times and display the corresponding images in quick succession. So, the code will naturally break down into the following three pieces: