title: Plot a data series beneath another one
body: <p>When you plot things in Matlab, the most recently plotted data series is placed on top of whatever's already there. For example:</p>
  
  <pre><code>figure; hold on
  plot(sin(linspace(0,pi)),'linewidth',4,'color',[0 0 1])
  plot(cos(linspace(0,pi)),'linewidth',4,'color',[1 0 0])
  </code></pre>
  
  <p>Here, the red line is shown on top of the blue line (where they intersect). Is there any way to set "how deep" a line is drawn, so that you can plot things <em>beneath</em> what's already there?</p>