 <code>log1m(x)</code> has the same value as <span class="math inline">\(\log(1 - x)\)</span>, but the computation is faster, more accurate, and more stable.</p>
<p>The constrained type <code>real&lt;lower=-1, upper=1&gt;</code> declared for <code>y</code> is critical for correct sampling behavior. If the constraint on <code>y</code> is removed from the program, say by declaring <code>y</code> as having the unconstrained scalar type <code>real</code>, the program would compile, but it would produce arithmet