4>Template parameters</h4>
<table border="1" summary="parameters">
<tbody>
<tr>
<th>Parameter</th>
<th>Description</th>
<th>Default</th>
</tr>
<tr>
<td><code>E1/E2</code></td>
<td>The type of the scalar expression.</td>
<td></td>
</tr>
<tr>
<td><code>E2/E1</code></td>
<td>The type of the vector expression.</td>
<td></td>
</tr>
<tr>
<td><code>F</code></td>
<td>The type of the operation.</td>
<td></td>
</tr>
</tbody>
</table>
<h4>Model of</h4>
<p><a href="expression_concept.htm#vector_expression">Vector Expre