by default so far.</p></dd>


<dt id="arg-x">x<a class="anchor" aria-label="anchor" href="#arg-x"></a></dt>
<dd><p>Numeric; vector for ages of use.</p></dd>


<dt id="arg-x-">x0<a class="anchor" aria-label="anchor" href="#arg-x-"></a></dt>
<dd><p>Numeric;  the x-value of the sigmoid's midpoint,</p></dd>


<dt id="arg-k">k<a class="anchor" aria-label="anchor" href="#arg-k"></a></dt>
<dd><p>Numeric; the steepness of the curve.</p></dd>


<dt id="arg-l">L<a class="anchor" aria-label="anchor" href="#arg-l"></a>