title: implementing chi-square to find distance between 2 SIFT feature
body: <p>I am trying to implement chi-square which algorithm is :<br></p>
  
  <pre><code>Distance= 1/2* Ei((Xi-Yi)^2/Xi+Yi)
  instead of euclidean distance which algorithm is:
  Distance= Sqrt(E(Xi-Yi)^2)
  in calculating distance between 2 SIFT feature (128 dimensional vector), 
  </code></pre>
  
  <p>my problem is the divider in chi- square could be 0 and it will make the distance bacome NaN. Should i make the divider into 1 or ignore it ? or there was another chi-square algorithm for calculating SIFT feature ?</p>