is evolved via
Hamilton’s equations,</p>
<p><span class="math display">\[
\begin{array}{rcccl}
\displaystyle
\frac{d\theta}{dt}
&amp; = &amp;
\displaystyle
+ \frac{\partial H}{\partial \rho}
&amp; = &amp;
\displaystyle
+ \frac{\partial T}{\partial \rho}
\\[12pt]
\displaystyle
\frac{d\rho}{dt}
&amp; = &amp;
\displaystyle
- \frac{\partial H}{\partial \theta }
&amp; = &amp;
\displaystyle
- \frac{\partial T}{\partial \theta}
- \frac{\partial V}{\partial \theta}.
\end{array}
\]</span></p>
<p>With the momentum 