: </dt><dd><ul class="simple">
<li><p>r  = a scalar whose value is the numerator of</p></li>
</ul>
<blockquote>
<div><p>argument to gudermannian function:
GD(x) = atan(tanh(r/x)). GD(x) is 
normalised to have a maximum value of 1.</p>
</div></blockquote>
</dd>
<dt>[DEPRICATED] linear:       </dt><dd><ul class="simple">
<li><p>r  = an integer value. When <code class="docutils literal notranslate"><span class="pre">r</span> <span class="pre">==</span> <span class="pre">0</span></code>, the</p></li>
</ul>
<blo