title: Geometric Mean: is there a built-in?
body: <p>I tried to find a built-in for geometric mean but couldn't.</p>
  
  <p>(Obviously a built-in isn't going to save me any time while working in the shell, nor do I suspect there's any difference in accuracy; for scripts I try to use built-ins as often as possible, where the (cumulative) performance gain is often noticeable.</p>
  
  <p>In case there isn't one (which I doubt is the case) here's mine. </p>
  
  <pre><code>gm_mean = function(a){prod(a)^(1/length(a))}
  </code></pre>