So, my code is this:

u := u1+(u2-u1)*JacobiSN((1/2)*phi*sqrt(s*(u3-u1)), k)^2;

r := 1/u 

where u1,u2, u3, s, and k, are just some constants

and here is where I think it's having problems 

Top := [r*cos(v), r*sin(v), 2*sqrt(s*(r-s))];
Bottom := [r*cos(v), r*sin(v)-2*sqrt(s*(r-s))]
figure(22) := plot3d([Top, Bottom], r = s .. 20, v = 0 .. 2*Pi)

It gives me this error: 

Error, (in plot3d...