title: Excel formula for Euclidean distance
body: <p>A former co-worker of mine uses this formula to do some cluster analysis:</p>
  
  <pre><code>{=SQRT(SUM(($C3:$F3-$C$11:$F$11)^2))} . 
  </code></pre>
  
  <p>He doesn't know why it works.</p>
  
  <p>It's meant to find the distance between some points. When I run the equation without the <code>{}</code> it gives me one answer. When I run it with it, I get another.</p>
  
  <p>Distance is normally <code>A^2+B^2=C^2</code>. I'm guessing this is doing it for a series of points in the row. Is this basically doing the each point in each of these rows?</p>
  
  <p>I just want to make sure we're not using something stupid.</p>