</span></span></span>
<span class="r-in"><span><span class="va">tglong</span> <span class="op">&lt;-</span> <span class="fu"><a href="expand.covs.html">expand.covs</a></span><span class="op">(</span><span class="va">tglong</span>,<span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="st">"x1"</span>,<span class="st">"x2"</span><span class="op">)</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="co"># 