# draw the Rastriging's function by the Gnuplot.
reset

set isosamples 80
set hidden3d
set contour base
set pm3d
set style line 100 lc rgb "gray20" lw 0.5
set pm3d hidden3d 100 # 見えない部分を非表示

set title "Rastrigin's function"
set xyplane at 0      # x-y平面をz=0の位置に固定
# set xyplane at -10      # x-y平面をz=0の位置に固定
set view 58,228
set xrange [-5.12:5.12]
set yrange [-5.12:5.12]
set zrange [0:80]
unset key
unset colorbox # カラーバーを非表示
set palette rgbformulae 22,13,-31 # 虹色に

splot (x**2 - 10*cos(2*pi*x) + 10) + (y**2 - 10*cos(2*pi*y) + 10) w l lw 0.5