y guarantees convergence, but the implementation
 does not.</p>

 <p>The <em>Regula Falsi</em> method assumes that the function is continuous,
 but not necessarily smooth.</p>

 <p>Implementation based on the following article: M. Dowell and P. Jarratt,
 <em>A modified regula falsi method for computing the root of an
 equation</em>, BIT Numerical Mathematics, volume 11, number 2,
 pages 168-174, Springer, 1971.</p></div>
<dl><dt><span class="strong">Since:</span></dt>
  <dd>3.0</dd>
<dt><span class="strong"