x</code>, then
<code>Sigma[1]</code> denotes the first row of <code>Sigma</code> and has the
type <code>row_vector</code>.</p>
</div>
<div id="mixing-array-and-vectormatrix-indexes" class="section level3 unnumbered">
<h3>Mixing array and vector/matrix indexes</h3>
<p>Stan supports mixed indexing of arrays and their vector, row vector
or matrix values. For example, if <code>m</code> is of type
<code>matrix[ , ]</code>, a two-dimensional array of matrices, then
<code>m[1]</code> refers to the first row of the