co"># fix entries in variance matrix</span></span>
<span><span class="va">variance.fixed</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://amices.org/mice/reference/cbind.html" class="external-link">cbind</a></span><span class="op">(</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="fl">1</span>,<span class="fl">1</span>,<span class="fl">2</span><span class="op">)</span>, <span class="fu"><a href="http