lowing.</p>
<pre class="stan"><code>real a[3, 4];</code></pre>
<p>A three-dimensional array <code>z</code> of positive reals with five rows, four
columns, and two shelves can be declared as follows.</p>
<pre class="stan"><code>real&lt;lower=0&gt; z[5, 4, 2];</code></pre>
<p>Arrays may also be declared to contain vectors. For example,</p>
<pre class="stan"><code>vector[7] mu[3];</code></pre>
<p>declares <code>mu</code> to be an array of size 3 containing vectors with 7
elements. Arrays may also contain matri