e style="margin-bottom: -1em;">
Specify the type of optimization scheme:
                  </pre>
<dl style="margin-left: 1.5em;">
<dt><tt><span class="flag">'sd'</span> :</tt></dt>
<dd><pre style="margin-top: 0em; margin-bottom: -1em;">
steepest descent
                  </pre></dd>
</dl>
<dl style="margin-left: 1.5em;">
<dt><tt><span class="flag">'broyden'</span> :</tt></dt>
<dd><pre style="margin-top: 0em; margin-bottom: -1em;">
quasi-Newton Broyden's second method (suggested)
                  </pre></d