title: Rough computation of distance between 2 points
body: <p>I want to calculate the rough (approximate) distance between two points to reduce the computation overhead.</p>
  
  <p>I am using the following formula for the distance between (x1, y1) &amp; (x2, y2):</p>
  
  <pre><code>Dist = Mod (x1 - x2) + Mod (y1 - y2)
  </code></pre>
  
  <p>Where Mod is the Modulus operator such that Mod(x) = |X|.</p>
  
  <p>This seems to be working.</p>
  
  <p>I want to know, if I have missed out something ...</p>