# set terminal pngcairo  background "#ffffff" enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'pm3d.35.png'
set border 4095 front linetype -1 linewidth 1.000
set format cb "%.01t*10^{%T}"
set samples 31, 31
set isosamples 31, 31
unset surface 
set ticslevel 0
set title "function 'x+y' using all colors available, 'set pal maxcolors 0'" 
set xlabel "X" 
set ylabel "Y" 
set pm3d implicit at s
splot x+y