n class="number">2</span><span class="special">];</span>
        <span class="identifier">dpert</span><span class="special">[</span><span class="number">2</span><span class="special">]</span> <span class="special">=</span> <span class="identifier">x</span><span class="special">[</span><span class="number">1</span><span class="special">]</span> <span class="special">*</span> <span class="identifier">pert</span><span class="special">[</span><span class="number">0</span><span class="special">]</span> <span cla