title: Empty plot gnuplot
body: <p>I am facing some trouble to make a simple plot.
  My .gnu file return an empty plot, like this :</p>
  
  <p>I want a heat map, the format of my data is X Y Z in the .gnu file and the header is like this :</p>
  
  <pre><code>cat plot.gnu | head -n 10 :
  
  set size square
  set pm3d map corners2color c1
  set xlabel ""
  set ylabel ""
  set yrange [   0.000:3003.000]
  set xrange [   0.000:3003.000]
  splot "-" with pm3d title "plot.gnu"
  1.000 1.000 0
  1.000 2.000 0
  1.000 3.000 0
  </code></pre>
  
  <p>and the footer is  like this :</p>
  
  <pre><code>cat plot.gnu | tail -n 10 
  
  3002.000 2996.000 0
  3002.000 2997.000 0
  3002.000 2998.000 0
  3002.000 2999.000 0
  3002.000 3000.000 0
  3002.000 3001.000 0
  3002.000 3002.000 0
  
  end
  pause -1
  </code></pre>
  
  <p>EDIT : A shorter script could be :</p>
  
  <pre><code>set size square
  set pm3d map corners2color c1
  set xlabel ""
  set ylabel ""
  set yrange [   0.000:4.000]
  set xrange [   0.000:4.000]
  splot "-" with pm3d title "plot.gnu"
  1.000 1.000 1
  1.000 2.000 2
  1.000 3.000 4
  1.000 4.000 5
  2.000 1.000 1
  2.000 2.000 0
  2.000 3.000 3
  2.000 4.000 1
  3.000 1.000 1
  3.000 2.000 0
  3.000 3.000 3
  3.000 4.000 0
  4.000 1.000 9
  4.000 2.000 0
  4.000 4.000 3
  4.000 4.000 2
  
  end
  pause -1
  </code></pre>
  
  <p>Do you have an idea ? 
  Thanks</p>