title: gnuplot heat map with different scales
body: <p>I have troubles creating a heat map with gnuplot for data with different scales.</p>
  
  <p>Consider the following sample data set:</p>
  
  <pre><code>0.100    1.000     10.0
  0.010    1.000     20.0
  0.001    1.000     40.0
  
  0.100    10.00     20.0
  0.010    10.00     40.0
  0.001    10.00     80.0
  
  0.100    100.0     40.0
  0.010    100.0     80.0
  0.001    100.0    160.0
  </code></pre>
  
  <p>If I plot it using a heatmap, it only seems to be correct if I scale the x-values such that they are in the same range as the y-values.</p>
  
  <p>Please find below an illustrating example. Only the second plot gives me the correct values of the heat map (high values in the top left corner, low values in the bottom right corner):</p>
  
  <pre><code>set multiplot layout 2,1
  
  set pm3d
  set dgrid3d 20,20
  set view map
  
  set xlabel 'unscaled'
  splot 'data.dat' u 1:2:3
  
  set xlabel 'scaled by factor 1000'
  splot 'data.dat' u ($1*1000):2:3
  </code></pre>
  
  <p>How can I achieve this also for the non-scaled values?</p>
  
  <p>Any help is appreciated. Many thanks.</p>