T := (x,y,z) -> x^2+y^2+3*z^2; T(0,1,-1); V := (r,h) -> Pi*r^2*h; g := unapply(sqrt(9-x^2-y^2),x,y); z1 := g(2,1); z2 := g(-1,Pi); z := g(x,y); plot3d(z,x=-3..3,y=-3..3,axes=framed,color=green); z := x*exp(-x^2-y^2); with(plots): contourplot(z,x=-2..2,y=-2..2,grid=[49,49], color = z);