title: issues with intersect in matlab
body: <p>Consider the following example:</p>
  
  <pre><code>time = datenum('2010-03-03 00:00','yyyy-mm-dd HH:MM'):60/(60*24):...
      datenum('2010-07-31 23:00','yyyy-mm-dd HH:MM');
  
  Jday = datenum('2010-01-01 00:00','yyyy-mm-dd HH:MM'):60/(60*24):...
      datenum('2010-12-31 23:00','yyyy-mm-dd HH:MM');
  
  idx = intersect(time,Jday);
  </code></pre>
  
  <p>Why isn't idx the same size as time? I would have thought that these should be identical in length seeing as time is just a portion of Jday. Any ideas? </p>