title: Doing calculations in gnuplot's plot command
body: <p>The following gnuplot code works good:</p>
  
  <pre><code>plot 'data.txt'  using 2:4  '   %lf %lf %lf %lf' title "1 PE" with linespoints;
  </code></pre>
  
  <p>In the following code, I want to say: "Use the number from column 4, but then divide it by the number from column 3". Or: "Use the number from column 2, but divide it by the constant 2.0". The following code demonstrates what I try to achieve, but it does not work.</p>
  
  <pre><code>plot 'data.txt'  using 2:4/4  '   %lf %lf %lf %lf' title "1 PE" with linespoints;
  plot 'data.txt'  using 2:4/2.0  '   %lf %lf %lf %lf' title "1 PE" with linespoints;
  </code></pre>
  
  <p>Is something like this possible?</p>