al">[</span><span class="number">0</span><span class="special">]</span> <span class="special">=</span> <span class="special">-</span> <span class="identifier">sigma</span> <span class="special">*</span> <span class="identifier">pert</span><span class="special">[</span><span class="number">0</span><span class="special">]</span> <span class="special">+</span> <span class="number">10.0</span> <span class="special">*</span> <span class="identifier">pert</span><span class="special">[</span><span class="number">1