entifier">d</span> <span class="special">=</span> <span class="identifier">finite_difference_derivative</span><span class="special">(</span><span class="identifier">f</span><span class="special">,</span> <span class="identifier">x</span><span class="special">,</span> <span class="special">&amp;</span><span class="identifier">error_estimate</span><span class="special">);</span>
</pre>
<p>
      N.B.: Producing an error estimate requires additional function evaluations
      and as such is slower than simple 