Colorful surfaces
f(x,y,z) = (x^2 + y^2)/2 - z
N = 1..6
Sk = Zip(f(x,y,k), k, N-3)
Lname = Zip("Z"+k, k, N)
Execute(Zip(name +"="+ S, name, Lname, S,Sk))
Execute(Zip("SetDynamicColor("+name+", random(), random(), random() )", name, Lname))