 class="p">(</span><span class="n">k</span><span class="p">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">mat_round</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
<span class="w">      </span><span class="n">z</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">z</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">d</span><span class="p">(</span