> 3 * (exp(a) + b)</span>
<span class="r-in"></span>
<span class="r-in"><span class="va">d</span> <span class="op">&lt;-</span> <span class="fu"><a href="portal.html">rand_normal</a></span><span class="op">(</span><span class="op">)</span></span>
<span class="r-in"></span>
<span class="r-in"><span class="co"># Define a closed form expression with another closed form expression</span></span>
<span class="r-in"><span class="va">cf2</span> <span class="op">&lt;-</span> <span class="fu"><a href="portal.html">cl