title: c++ find eigenvalues and eigenvectors of matrix
body: <p>I'm writing an algorithm with a lot of steps (PCA), and two of them are finding eigenvalues and eigenvectors of a given matrix.</p>
  
  <p>I do not wish to write the whole code for it because I know it is a long job, so I searched for some adhoc code for that but just found 1 or 2 libraries and at first I prefer not to include libraries and I don't want to move to matlab.</p>
  
  <p>Is there any algorithm/tutorial/code that doesn't seem very hard to follow?</p>