span class="p">]):</span>
            <span class="k">if</span> <span class="n">n</span><span class="p">[</span><span class="n">j</span><span class="p">]</span> <span class="o">!=</span> <span class="mf">0.0</span><span class="p">:</span>
                <span class="n">v_x</span><span class="p">[</span><span class="n">j</span><span class="p">]</span> <span class="o">=</span> <span class="p">(</span>
                    <span class="n">p</span><span class="p">[</span><span class="s2">&quot;a&quot;</span><sp