title: Fatal error: Call to undefined function easter_date()
body: <p>I'm trying to get the easter_date from this year.
  This is my code:</p>
  
  <pre><code>&lt;?php
  $year = date ("Y");
  $easter = date ("d-M-Y", easter_date ($year));
  echo "Easter " . $year . ": " . $easter . "";
  ?&gt;</code></pre>
  
  <p>When I execute the code following error appears:
  Fatal error: Call to undefined function easter_date() in</p>
  
  <p>My phpVersion is 5.3.3. I'm using Linux(Ubuntu).</p>
  
  <p>Have you got an idea what is missing?</p>