ansformation using
    text substitution and demonstrates that the result can be 
    executed (for specific values of <code>t</code> and <code>s1</code>).
  </p>
<div class="chunk" id="unnamed-chunk-5"><div class="rcode"><div class="source"><pre class="knitr r"><span class="hl std">hblend</span> <span class="hl kwb">&lt;-</span> <span class="hl str">&quot;u*(q + u*(2*q + u*u*(-2*q - u*q)))&quot;</span>
<span class="hl std">A0</span> <span class="hl kwb">&lt;-</span> <span class="hl kwd">gsub</span><span cl