# set terminal pngcairo  transparent enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'pm3d.9.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 lines
set xyplane at -0.26
set title "colour map, using default rgbformulae 7,5,15 ... traditional pm3d (black-blue-red-yellow)" 
set xlabel "x" 
set xrange [ -15.0000 : 15.0000 ] noreverse
set ylabel "y" 
set yrange [ -15.0000 : 15.0000 ] noreverse
set zrange [ -0.250000 : 1.00000 ] noreverse
set pm3d implicit at s
NO_ANIMATION = 1
splot sin(sqrt(x**2+y**2))/sqrt(x**2+y**2)