 induces three rules,</p>
<ol start="4" style="list-style-type: decimal">
<li><code>vector</code> may be promoted to <code>complex_vector</code>,</li>
<li><code>row_vector</code> may be promoted to <code>complex_row_vector</code></li>
<li><code>matrix</code> may be promoted to <code>complex_matrix</code>.</li>
</ol>
<p>For array types, there’s a single rule</p>
<ol start="7" style="list-style-type: decimal">
<li><code>array[...] U</code> may be promoted to <code>array[...] T</code> if <code>U</code> can b