</span> <span class="p">;</span> <span class="n">radius</span> <span class="p">;</span> <span class="n">theta</span><span class="p">]</span> <span class="p">;</span>
<span class="n">vl_plotframe</span><span class="p">(</span><span class="n">f</span><span class="p">)</span> <span class="p">;</span>
</pre></div>


<p>As indicated above, frames are often used to specify image
transformations. In particular, oriented ellipses and oriented circles
can be obtained by a unique affine transformation of the standard