>a[i] ==   m[1, i + 1]</code>, whereas in the second case, <code>a[i] == m[i + 2,   5]</code>.</p>
<p>Continuing the previous example, consider the following.</p>
<div class="sourceCode" id="cb23"><pre class="sourceCode stan code-with-copy"><code class="sourceCode stan"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="co">// ...</span></span>
<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="dt">vector</span>[<span class="dv">2</span>]