# set terminal png transparent nocrop enhanced font arial 8 size 420,320 
# set output 'pm3d.33.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 xrange [ * : * ] noreverse nowriteback  # (currently [-185.000:185.000] )
set ylabel "Y" 
set yrange [ * : * ] noreverse nowriteback  # (currently [-185.000:185.000] )
set pm3d implicit at s
splot x+y