Recent content by Jess_l

I've been looking at the torus parametrization \begin{equation} \phi(u,v)=((r\cos u+a)\cos v, (r\cos u +a)\sin v, r\sin u) \end{equation} with \begin{equation}a>0, r\in(0,a)\end{equation}. I want to invert this map to get a chart map for the torus. Can anyone give me a hand with this? Thanks!