title: How do I compute the absolute value of a vector in Eigen?
body: <p>How do I compute the absolute value of a vector in Eigen? Since the obvious way</p>
  
  <pre><code>Eigen::VectorXf v(-1.0,-1.0,-1.0,-1.0,-1.0,-1.0,-1.0);
  v.abs(); // Compute abs value.
  </code></pre>
  
  <p>does not work.</p>