# set terminal pngcairo  transparent enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'pm3d.12.png'
set border 4095 front lt black linewidth 1.000 dashtype solid
set view map scale 1
set samples 50, 50
set isosamples 50, 50
unset surface 
set style data pm3d
set style function pm3d
set xyplane relative 0
set title "cubehelix color scheme with monotonic intensity\nD A Green (2011) http://arxiv.org/abs/1108.5083" 
set title  offset character 0, 1, 0 font "" norotate
set xlabel "x" 
set xrange [ -15.0000 : 15.0000 ] noreverse nowriteback
set ylabel "y" 
set yrange [ -15.0000 : 15.0000 ] noreverse nowriteback
set zrange [ -0.250000 : 1.00000 ] noreverse nowriteback
set pm3d implicit at b
set palette cubehelix start 0.5 cycles -1.5 saturation 1
splot sin(sqrt(x**2+y**2))/sqrt(x**2+y**2)