/span> <span class="o">==</span> <span class="mi">0</span><span class="p">)</span><span class="k">then</span>
<span class="k">    return</span>
<span class="k">  </span><span class="n">elseif</span><span class="p">(</span><span class="n">idm</span> <span class="o">==</span> <span class="mi">1</span><span class="p">)</span><span class="k">then</span>
<span class="k">    </span><span class="n">dx</span> <span class="o">=</span> <span class="mi">0</span>
    <span class="k">return</span>
<span class="k">  </sp