# set terminal png transparent nocrop enhanced font arial 8 size 420,320 
# set output 'pm3dcolors.4.png'
set view map
set samples 101, 101
set isosamples 2, 2
set style data pm3d
set style function pm3d
set xtics border in scale 1,0.5 mirror norotate  offset character 0, 0, 0 2
set noytics
set noztics
set title "set palette defined ( 20 \"#101010\", 30 \"#ff0000\", 40 \"#00ff00\", 50 \"#e0e0e0\" )" 
set xrange [ -10.0000 : 10.0000 ] noreverse nowriteback
set cbrange [ -10.0000 : 10.0000 ] noreverse nowriteback
set pm3d implicit at b
set palette defined ( 0 0.06275 0.06275 0.06275, 0.3333 1 0 0, 0.6667 0 1 0,\
     1 0.8784 0.8784 0.8784 )
splot x