title: Recommendations for Fast Multipole Method implementation?
body: <p>I'm interested in implementing the <a href="http://en.wikipedia.org/wiki/Fast_multipole_method" rel="noreferrer">Fast Multipole Method</a> to efficiently simulate a system of repulsive particles.</p>
  
  <p>I've found a large collection of references discussing FMM, but none seem very approachable for non-mathematicians who want to fully understand the algorithm.</p>
  
  <p>Can you recommend a ground-up reference that clearly explains the mathematics behind the process, and includes pseudocode exemplifying a proper implementation? </p>