variance -->
</pre>

<h2>The <i>where</i> function</h2>

<p>
The <i>where(X,Y,Z)</i> function provides the same functionality as
the operator X ? Y : Z.  If X is logical true, then Y is returned;
otherwise, Z is returned.
</p>

<p>
The <i>where</i> function is implemented using expression templates.
The arguments X, Y, and Z can each be vectors, vector expressions,
<a href="range.html">Range</a>, or Vector picks.
</p>

<a name="example">
<h2>Example</h2>

Please see the files in the <a href="../examples/"><