ng <a href="http://en.wikipedia.org/wiki/Loss_of_significance" target="_top">loss
          of significance</a>. To counteract this, the complement versions of
          CDF and quantile are implemented with alternative expressions using <span class="emphasis"><em>cos<sup>-1</sup></em></span>
          instead of <span class="emphasis"><em>sin<sup>-1</sup></em></span>. Users should see <a class="link" href="../../stat_tut/overview/complements.html#why_complements">why
          complements?</a> for guidance