        Numeric Recipes in C++, W. H. Press et all, chapter 5, (especially 5.2 Evaluation
        of continued fractions, p 175 - 179) for more information, also Lentz, W.J.
        1976, Applied Optics, vol. 15, pp. 668-671.
      </p>
<h5>
<a name="math_toolkit.internals.cf.h3"></a>
        <span class="phrase"><a name="math_toolkit.internals.cf.examples"></a></span><a class="link" href="cf.html#math_toolkit.internals.cf.examples">Examples</a>
      </h5>
<p>
        The <a href="http://en.wikipedia.org/w