title: Is dpi relevant when figure is saved as PDF?
body: <p>If I am saving figures as PDF, is <code>dpi</code> still relevant? For example, in the following code</p>
  <pre class="lang-py prettyprint-override"><code>import pylab
  
  pylab.savefig('./test_200.pdf', dpi = 200)
  pylab.savefig('./test_2000.pdf', dpi = 2000)
  </code></pre>
  <p>does <code>dpi</code> make a difference?</p>
  <p>To me it does not make a difference at least in resolution, I have zoomed in as much as I can and the two figures look the same</p>
  <p><a href="https://i.stack.imgur.com/ozYoL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ozYoL.png" alt="dpi" /></a></p>
  <p>Is it possible that there are any underlying difference or simply no difference? Thank you in advance!</p>