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


<p>A positive rotation of the frame appears clockwise because the
image coordinate system is left-handed (Y axis pointing
downwards):</p>

<div class="figure">
 <img src="../demo/frame_rotated.jpg"></img>
 <div class="caption">
  <span class="content">
    A frame rotated by 45 degrees; note that the rotation is
    clockwise: this is because the image uses a left-hande