set terminal povray set dummy u,v set samples 100 set isosamples 100 set zrange [-1:1] sinc(u,v) = sin(sqrt(u**2+v**2)) / sqrt(u**2+v**2) set out "tmp.pov" splot [-20:20] [-20:20] sinc(u,v) with dots, \ " povray-demo5.pov ! povray +A0.1 +FC +I povray-demo5.pov