mial.html">negative.binomial</a></code>.</p>
<p><b>Optimization:</b> A hybrid approach is used, starting with <code>iter_EM</code> iterations
and unless convergence was achieved it continuous with a direct optimization of the
log-likelihood using function <code><a href="https://rdrr.io/r/stats/optim.html" class="external-link">optim</a></code> and the algorithm specified by
<code>optim_method</code>. For stability and speed, the derivative of the log-likelihood with
respect to the parameters are internally 