on.
        </p>
<p>
          This function uses numeric inversion of the negative binomial distribution
          to obtain the result: another interpretation of the result, is that it
          finds the number of trials (success+failures) that will lead to an <span class="emphasis"><em>alpha</em></span>
          probability of observing more than k failures.
        </p>
<h5>
<a name="math_toolkit.dist_ref.dists.negative_binomial_dist.h8"></a>
          <span class="phrase"><a name="math_toolkit.dist_r