title: How do I reduce a symmetric matrix to a tridiagonal matrix with the same eigenvalues?
body: <p>I have a symmetric matrix found from the following commands:</p>
  
  <pre><code>a=rand(n);
  A=triu(a)+triu(a,1)'
  </code></pre>
  
  <p>I was wondering how I reduce this symmetric matrix into a tridiagonal matrix?</p>
  
  <p>Any help is appreciated. Thank you very much.</p>