>xi</span><span class="p">,</span><span class="n">yr</span><span class="p">,</span><span class="n">yi</span><span class="p">)</span>

<span class="c">! ident_47=&quot;@(#)M_LA::mat_watan(3fp): y = atan(x) = (i/2)*log((i+x)/(i-x))&quot;</span>

<span class="n">doubleprecision</span><span class="w"> </span><span class="kd">::</span><span class="w"> </span><span class="n">xr</span>
<span class="n">doubleprecision</span><span class="w"> </span><span class="kd">::</span><span class="w"> </span><span class="n">xi