n">roll</span><span class="p">(</span><span class="n">hbincenters</span><span class="o">.</span><span class="n">copy</span><span class="p">(),</span><span class="mi">1</span><span class="p">)</span>
        <span class="n">dtU</span> <span class="o">=</span> <span class="n">dU</span><span class="o">-</span><span class="n">hbincenters</span>
        <span class="n">dtL</span> <span class="o">=</span> <span class="n">hbincenters</span> <span class="o">-</span><span class="n">dL</span>
        <span class="n">