n><span class="fl">3</span><span class="op">)</span></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co"># using row operations to reduce below diagonal to 0</span></span></span>
<span class="r-in"><span><span class="va">Abt</span> <span class="op">&lt;-</span> <span class="va">Ab</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/cbind.html" class="external-link">cbind</a></span><span class="op">(</span><span class="va">A</span>