pan class="va">Z</span><span class="op">[</span>,<span class="fl">3</span><span class="op">]</span><span class="op">)</span></span></code></pre></div>
<p>Note that if any column of <code>X</code> is a linear combination of
the previous columns, the corresponding column of <code>Z</code> will be
all zeros.</p>
<p>These computations are similar to the following set of linear
regressions:</p>
<div class="sourceCode" id="cb9"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="va">z