hat this is not an oscillation, but an instability with $\theta
      \rightarrow \pm \infty$. </p>

      <p>You can find another beautiful example of these concepts (fixed points, basins of attraction, bifurcations) from recurrent neural networks in the exercise below on <a href="#hopfield">Hopfield networks</a>.</p>

    </subsection> <!-- end of overdamped pend -->

    <subsection id="pend_zero_torque"><h1>The undamped pendulum with zero torque</h1>

      <p> Consider again the system $$ml^2 \ddot\the