ect</code> functions support the construction
of matrix slices.</p>

<h4>Definition</h4>

<p>Defined in the header matrix_proxy.hpp.</p>

<h4>Type requirements</h4>

<ul>
<li><code>M</code> is a model of <a href=
"expression.htm#matrix_expression">Matrix Expression</a> .</li>
</ul>

<h4>Preconditions</h4>

<ul type="Disc">
<li><code>s1.start () + s1.stride () * s1.size () &lt;= data.size1
()</code></li>

<li><code>s2.start () + s2.stride () * s2.size () &lt;= data.size2
()</code></li>
</ul>

<h4>Complexity<