# set terminal png transparent nocrop enhanced font arial 8 size 420,320 
# set output 'contours.11.png'
set samples 20, 20
set isosamples 21, 21
set contour base
set cntrparam levels auto 10
set title "3D gnuplot demo - some more interesting contours" 0.000000,0.000000  font ""
set xlabel "X axis" -5.000000,-2.000000  font ""
set ylabel "Y axis" 4.000000,-1.000000  font ""
set zlabel "Z axis" 0.000000,0.000000  font ""
set zrange [ -1.00000 : 1.00000 ] noreverse nowriteback
splot [x=-3:3] [y=-3:3] sin(x) * cos(y)