title: How to implement the imrotate functioin using OpenCV
body: <p>Yes. I want to get the same result like the imrotate in matlab, but I can't get the point.
  More specifically，I get a mat A</p>
  
  <blockquote>
    <p>a =</p>
  </blockquote>
  
  <pre><code> 1     2     3
   4     5     6
  </code></pre>
  
  <blockquote>
    <blockquote>
      <blockquote>
        <p>imrotate(a, 45)</p>
      </blockquote>
    </blockquote>
  </blockquote>
  
  <p>ans =</p>
  
  <pre><code> 0     0     0     0     0
   0     0     3     6     0
   0     1     2     6     0
   0     1     4     0     0
   0     0     0     0     0
  </code></pre>
  
  <p>How can I do that using OpenCV?</p>