title: Simple 3x3 matrix inverse code (C++)
body: <p>What's the easiest way to compute a 3x3 matrix inverse?</p>
  
  <p>I'm just looking for a short code snippet that'll do the trick for non-singular matrices, possibly using Cramer's rule.  It doesn't need to be highly optimized. I'd prefer simplicity over speed. I'd rather not link in additional libraries.</p>