>.</p>
<p>It might be tempting to try to just declare theta directly as a
parameter with the lower and upper bound constraint as given above.
The drawback to this approach is that the values <span class="math inline">\(-\pi\)</span> and <span class="math inline">\(\pi\)</span> are
at <span class="math inline">\(-\infty\)</span> and <span class="math inline">\(\infty\)</span> on the unconstrained scale, which can
produce multimodal posterior distribtions when the true distribution
on the circle is unimodal.<