title: Correctly indexing latitude and longitude values in Lucene
body: <p>Am working on a  "US based nearest city search within a given radius" functionality using Lucene API.
  Am indexing city's lat and long values in Lucene as follows:</p>
  
  <pre><code>doc.Add(new Field("latitude", paddedLatitude, Field.Store.YES, Field.Index.UN_TOKENIZED));
  
  doc.Add(new Field("longitude", paddedLongitude, Field.Store.YES, Field.Index.UN_TOKENIZED));
  </code></pre>
  
  <p>Since Lucene only understands strings and not numbers, am padding lat and long values.</p>
  
  <p>For example, if original lat and long are 41.811846 and -87.820628 respectively, after padding,values look like:</p>
  
  <p>paddedLatitude -->"0041.811846" and paddedLongitude-->"-087.820628" </p>
  
  <p>Am doing the same padding while building the nearest city query(using Lucene's ConstantScoreRangeQuery class).</p>
  
  <p>Given the fact that lat and long values could be decimal/negative numbers, is this the right approach to index them so that I would get correct nearest cities in the search results when lucene would perform a number Range/comparison operation on these values?</p>
  
  <p>Thanks.</p>