plot_xmesh:=plot_ymesh:=40;
plot(sin(x+cos y), x=(0 .. 3*pi/2), y=(0 .. 3*pi/2), contour,nosurface,view="0,0");
plot_xmesh:=plot_ymesh:=80;
plot(tan(x*y), x=(-pi .. pi), y=(-pi .. pi), z=(-3 .. 3), contour,nosurface,view="0,0");
plot_xmesh:=plot_ymesh:=30;
plot(e^
(-sqrt(x^
2+y^
2))*cos(atan(x/y)), x=(-1 .. 1), y=(-1 .. 1),
contour,nosurface,view="0,0");
. Macsyma . Maple . Mathematica