having the
unconstrained scalar type <code>real</code>, the program would compile, but
it would produce arithmetic exceptions at run time when the sampler
explored values of <code>y</code> outside of <span class="math inline">\((-1,1)\)</span>.</p>
<p>Now suppose the log probability function were extended to all of
<span class="math inline">\(\mathbb{R}\)</span> as follows by defining the probability to be <code>log(0.0)</code>,
i.e., <span class="math inline">\(-\infty\)</span>, for values outside of <span