title: Gnuplot: Shrink axes to plot ("tight" axes)
body: <p>I have a datafile that I would like to create a <code>pm3d map</code> splot of. Code:</p>
  
  <pre><code>set term pngcairo size 800,600
  set out "test.png"
  set pm3d map
  splot "fill.dat"
  </code></pre>
  
  <p>Problem is, with the odd (but regular) spacings using in the data, <code>gnuplot</code> creates a huge white margin around the actual image.
  <img src="https://i.stack.imgur.com/GNDem.png" alt="basic result"></p>
  
  <p>I want to look it like the following, but <strong>without setting the x- and yrange manually</strong>. I think I remember there being an option in <code>gnuplot</code> to achieve a 'tight' fitting of the axes, but I don't recall the actual command.</p>
  
  <p><img src="https://i.stack.imgur.com/ZL1tG.png" alt="desired result"></p>
  
  <p>Content of file <code>fill.dat</code></p>
  
  <pre><code>1.1 1.2 3
  1.1 2.4 4
  1.1 3.6 2
  
  2.2 1.2 5
  2.2 2.4 1
  2.2 3.6 2
  
  3.3 1.2 7
  3.3 2.4 2
  3.3 3.6 5
  </code></pre>