an><span class="fu">::</span><span class="fu"><a href="https://rdrr.io/pkg/Matrix/man/drop0.html" class="external-link">drop0</a></span><span class="op">(</span><span class="va">m</span><span class="op">)</span></span></span>
<span class="r-in"><span>  <span class="co"># return matrix</span></span></span>
<span class="r-in"><span>  <span class="va">m</span></span></span>
<span class="r-in"><span><span class="op">}</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">p4</sp