 + b^{2} v_{2} + w_{2}\end{matrix}\right] \end{align}\]</span></p>
<div class="sourceCode" id="cb6"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="co"># &lt;!-- ```{r} --&gt;</span>
<span class="co"># &lt;!-- x_index &lt;- 1:4 --&gt;</span>
<span class="co"># &lt;!-- Kxx &lt;- K2[x_index, x_index] --&gt;</span>
<span class="co"># &lt;!-- Kxy &lt;- K2[x_index, -x_index] --&gt;</span>
<span class="co"># &lt;!-- Kyx &lt;- K2[-x_index, x_index] --&gt;</span>
<span class="co"># &lt;!-