                 </p>
                </td>
<td>
                  <p>
                    The probability of obtaining <span class="bold"><strong>k failures
                    or fewer</strong></span> from k+r trials with success fraction p and
                    success on the last trial. For example:
                  </p>
<pre class="programlisting"><span class="identifier">cdf</span><span class="special">(</span><span class="identifier">negative_binomial</span><span class="special">(</span><span clas