title: Data comparison with R
body: <p>I am writing a script for my mass spectrometric data.<br>
  I have the data in a Matrix named <code>M1</code>. Every sample is in his own column.</p>
  
  <p>Sample of M1:</p>
  
  <pre><code>   S1  S2  S3 
  1 100 200 500 
  2 200 300 500
  3 100 200 500
  </code></pre>
  
  <p>Now when I place de data in the matrix I can compare the columns by <code>M1$S1==M1$S2</code>. and same for other samples.</p>
  
  <p>How do I make this code run automatically all the samples?<br>
  So that it compares 1 with 2 and 1 with 3 and computes further?</p>
  
  <p>Maybe if it is possible is there a way to not get a true and false list but just the false samples?</p>