Solución

r(u,v)=u,v,13(162u+4v)    para    u<    y    v<\bold{r}(u, v) = \lang u, v,\frac13(16 − 2u + 4v) \rang\;\;\text{para}\;\; |u| \lt \infin\;\;\text{y}\;\; |v| \lt \infin