Calculate unit normal vector on surface for a given position
\[\begin{split}\frac{\partial\Phi}{\partial\theta}(r,\phi,\theta)\times
\frac{\partial\Phi}{\partial\phi}(r,\phi,\theta)=
\begin{bmatrix}
-r^2\cos(\phi)\sin(\theta)^2\\
r^2\sin(\phi)\sin(\theta)^2\\
-r^2\sin(\theta)\cos(\theta)\left[\sin(\phi)^2-\cos(\phi)^2\right]\\
\end{bmatrix}\end{split}\]
with radius \(r\), polar angle \(\phi\) and cylinder length
\(z\).
- Parameters:
- poslist
Position
- Returns:
- normallist
Normal vector