   significantly reduce the enclosing interval, even though they rapidly approach
      the root. This is also in contrast to some other derivative-free methods (for
      example, Brent's method described at <a href="http://en.wikipedia.org/wiki/Brent%27s_method" target="_top">Brent-Dekker)</a>
      which only reduces the enclosing interval on the final step. Therefore these
      methods return a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="i