set pm3d depth lighting primary 0.6
set object rect from sc 0,0 to sc 1,1 behind fc "#331100"
set palette rgbformulae 5,7,15
set samples 128
set isosamples 128
unset border
unset tics
unset colorbox
unset key
set xyplane 0
set view 45,15, 1.5,
set term pngcairo size 360,360
set out "func001.png"

f(x,y) = 3*(1-x)**2*exp(-x**2 - (y+1)**2)\
         - 10*(x/5.0 - x**3 - y**5)*exp(-x**2 - y**2)\
         - exp(-(x+1)**2 - y**2)/3
c = 3
set xrange [-c:c]
set yrange [-c:c]

splot f(x,y) w pm3d
!display func001.png