title: Calculating eigenvectors/values of a 2x2 tensor
body: <p>I'm implementing the system described within <a href="http://people.oregonstate.edu/~cheng/street_sig08/street_sig08.pdf" rel="nofollow">this paper</a>, and I'm getting a little stuck. I only recently encountered tensors/eigenvalues etc so excuse me if this is a little simple!</p>
  
  <p>Given a 2x2 tensor, how can I calculate the major and minor eigenvectors of it?</p>
  
  <p>Bonus points for implementations which are easy to translate into C# ;)</p>