r in which elements of <code>ys</code> are visited is defined for container types as follows.</p>
<ul>
<li><p><code>vector</code>, <code>row_vector</code>: elements visited in order, <code>y</code> is of type <code>double</code></p></li>
<li><p><code>matrix</code>: elements visited in column-major order, <code>y</code> is of type <code>double</code></p></li>
<li><p><code>T[]</code>: elements visited in order, <code>y</code> is of type <code>T</code>.</p></li>
</ul>
<p>Consequently, if <code>ys</code> is a t