title: Access opencv matrix CV_32S element
body: <p>If I have a matrix of type <code>CV_32SC1</code>, what typename should I use in function <code>Mat::at</code>?</p>
  
  <p>e.g.</p>
  
  <pre><code>Mat X;  // for example eye matrix of size 10,10,and type CV_32SC1
  X.at&lt;??????&gt;(1,1)=5;
  </code></pre>
  
  <p>How can I find the typename for other matrix types?</p>