title: How is qt() implemented in R?
body: <p>I'm trying to find out how <code>qt()</code> is implemented in R, but the commando <code>qt</code> without argument yields information that doesn't seem to help me much further:</p>
  
  <pre><code>function (p, df, ncp, lower.tail = TRUE, log.p = FALSE) 
  {
      if (missing(ncp)) 
          .External(C_qt, p, df, lower.tail, log.p)
      else .External(C_qnt, p, df, ncp, lower.tail, log.p)
  }
  &lt;bytecode: 0x0000000014f56158&gt;
  &lt;environment: namespace:stats&gt;
  </code></pre>
  
  <p>So far I could only find that <code>.External</code> refers to a type of code. <code>C_qt</code> and <code>C_qnt</code> don't want to be found: <a href="https://www.google.com/search?q=C_qt&amp;domains=r-project.org&amp;sitesearch=r-project.org&amp;btnG=Google+Search&amp;gws_rd=ssl#domains=r-project.org&amp;q=%22C_qt%22+site%3Ar-project.org" rel="nofollow">https://www.google.com/search?q=C_qt&amp;domains=r-project.org&amp;sitesearch=r-project.org&amp;btnG=Google+Search&amp;gws_rd=ssl#domains=r-project.org&amp;q=%22C_qt%22+site%3Ar-project.org</a></p>
  
  <p>Does anybody know a way to extract the method used by <code>R</code> to approximate the quantile function? I don't mind complexity, I'm just really interested in the final expression and answer. <code>:-)</code></p>