3D function graph with Taylor 2nd order

Function: \(f:\mathbb{R}^2\to\mathbb{R}\)
\(f(x):=a_{11}\cos(\pi a_{12}x)\cos(a_{13}y)\)

The derivatives to compute the tangent plane are implemented analytically.

Based on example of Alfred Wassermann, Uni Bayreuth,
Wigand Rathmann, FAU