DINI SURFACE
\[ X(u,v)=\left(\cos u\sin v,\sin u\sin v,\cos v+\ln\tan\frac{v}{2}+\frac{1}{5}\,u\right),\quad 0\le u\le 4\pi,\ 0.01\le v\le 3.13 \]
DINI SURFACE
\[ X(u,v)=\left(\cos u\sin v,\sin u\sin v,\cos v+\ln\tan\frac{v}{2}+\frac{1}{5}\,u\right),\quad 0\le u\le 4\pi,\ 0.01\le v\le 3.13 \]