title: How to set a variable line width when plotting?
body: <p>I would like to plot a curve with a variable line width. I normally would do the following if I wanted to use points instead of a line:</p>
  
  <pre><code>gnuplot&gt; plot 'curve.dat' u ($1):($2):($1) ps var
  </code></pre>
  
  <p>where <em>curve.dat</em> is filled with:</p>
  
  <pre><code>0  0
  1  1
  2  4
  3  9
  4  16
  5  25
  </code></pre>
  
  <p>and so on. Now if I try something similar for the <em>line width</em>:</p>
  
  <pre><code>gnuplot&gt; plot 'curve.dat' u ($1):($2):($1) lw var
  </code></pre>
  
  <p>I get the error message:</p>
  
  <pre><code>undefined variable: var
  </code></pre>
  
  <p>Or is this something that cannot be done with gnuplot?</p>