set pm3d depth lighting set object rect from sc 0,0 to sc 1,1 behind fc "#114400" set palette defined (0 "#6666ff", 1 "#6666ff") set samples 128 set isosamples 128 unset border unset tics unset colorbox unset key set xyplane 0 set view 70,15, 1.4, set term pngcairo size 360,360 set out "cassini.png" c = 1 set xrange [-2*c:2*c] set yrange [-2*c:2*c] set zrange [0:4*c] f(x,y) = (x**2+y**2+1)**2 - 4*x**2 z(x,y) = !(f(x,y) > 0 ) | y > 0 | x < 0 ? f(x,y)**0.25 : 1/0 splot z(x,y) w pm3d !display "cassini.png"