pan class="fl">2</span><span class="op">]</span>, <span class="va">Z</span><span class="op">[</span>,<span class="fl">1</span><span class="op">]</span><span class="op">)</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/base/crossprod.html" class="external-link">crossprod</a></span><span class="op">(</span><span class="va">Z</span><span class="op">[</span>,<span class="fl">1</span><span class="op">]</span>, <span class="va">Z</span><span class="op">[</span>,<span class="fl">2</span><span class