set samples 50
set isosamples 50
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
unset key
set label "{/Helvetica=18 splot with lines}" at sc 0.4,0.9
set xlabel "Ｘ軸" font "IPAGothic,12"
set ylabel "Ｙ軸" font "IPAMincho,12"
set zlabel "Ｚ軸" font "VLGothic,12"
set ticslevel 0
set term pngcairo enh font "Times,10" size 480,360
set out "mesh_lines.png"
splot [-3:3][-3:3] f(x,y) w lines