with(plots):
macro(palegreen=COLOR(RGB, .7, .9, .7),paleyellow=COLOR(RGB,.9,.9,.6));
f:=(x,y) -> cos(x^2*y);
p1:=plot3d(f(x,y), x=-2*Pi/3..2*Pi/3, y=-2*Pi/3..2*Pi/3, axes=boxed, color=palegreen):
p2:=spacecurve([0,y,f(0,y)], y=-2*Pi/3..2*Pi/3, color=red, thickness=2):
p3:=spacecurve([x,0,f(x,0)], x=-2*Pi/3..2*Pi/3, color=blue, thickness=2):
p4:=plot3d([x,0,z], x=-2*Pi/3..2*Pi/3, z=-2..2, color=paleyellow):
p5:=plot3d([0,y,z], y=-2*Pi/3..2*Pi/3, z=-2..2, color=paleyellow):
display(p1,p3,p4);
display(p1,p2,p5);