title: When to use Eigen::Vector vs std::vector?
body: <p>Because of external dependencies, I'm required to write some data in a <code>Eigen::VectorXi</code> container.</p>
  
  <p>However, there are other times in which I'm not required to use en <code>Eigen::VectorXi</code> as a container, and I may use a standard <code>std::vector&lt;int&gt;</code></p>
  
  <p>Currently I have <code>Eigen</code> and <code>std</code> vectors sprinkled through my code. The only times in which I decide to use an <code>std:vector</code> is when I'll be making insertions on the fly, since resizing and reinserting is more tedious (and possibly computationally expensive) than using <code>push_back(&lt;value&gt;)</code></p>
  
  <p>I'd like to be sure that I'm using one or the other in the right time, instead of randomly choosing. What are the right instances to use <code>Eigen::Vector</code> instead of <code>std::vector</code>?</p>