sgn, lp1
<a name="l01154"></a>01154   
<a name="l01155"></a>01155       lp1 = l + 1
<a name="l01156"></a>01156   
<a name="l01157"></a>01157       <span class="comment">! Reflect across anti-diagonal.</span>
<a name="l01158"></a>01158   
<a name="l01159"></a>01159       <span class="keyword">do</span> i = 1, l
<a name="l01160"></a>01160         <span class="keyword">do</span> j = l + 1, 2 * l + 1 - i
<a name="l01161"></a>01161           dl(2 * l + 2 - i - lp1, 2 * l + 2 - j - lp1) = dl(j - lp1, i - lp1)
<a 