rn is just equal to <code>c</code>.</p>
</section>
<section id="slicing-functions" class="level3 unnumbered">
<h3 class="unnumbered anchored" data-anchor-id="slicing-functions">Slicing functions</h3>
<p>Stan provides <code>head</code> and <code>tail</code> functions that pull out prefixes or suffixes of vectors, row vectors, and one-dimensional arrays. In each case, the return type is the same as the argument type. For example,</p>
<pre><code>vector[M] a = ...;
vector[N] b = head(a, N);</code></pre>
<p>assi