e inverse <span class="math inline">\(\Sigma^{-1}\)</span> is known as the mass
matrix, and will be a unit, diagonal, or dense if <span class="math inline">\(\Sigma\)</span> is.</p>
</div>
<div id="the-hamiltonian" class="section level3 unnumbered">
<h3>The Hamiltonian</h3>
<p>The joint density <span class="math inline">\(p(\rho, \theta)\)</span> defines a Hamiltonian</p>
<p><span class="math display">\[
\begin{array}{rcl}
H(\rho, \theta) &amp; = &amp; - \log p(\rho, \theta)
\\[3pt]
&amp; = &amp; - \log p(\