11.3.3 Can you answer these questions?

11.3.3.1 2D differentiation matrix

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=310243

 NDSolve`FiniteDifferenceDerivative  is a very helpful function to calculate numerical derivatives. It is explained  in the tutorial The Numerical Method of Lines in ... 
[differential-equations] [implementation-details] [finite-difference-method]
 

asked by Ulrich Neumann https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53677 Score of 2

11.3.3.2 Recurrence problem

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=310066

Here is the code : 
Generation of the pulse signal with parameters Vmin, Vmax, Subscript[t, r], Subscript[t, f], Subscript[t, on], T 
... 
[recursion]
 

asked by Elie CAMPAGNOLO https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=105219 Score of 1

answered by ydd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72953 Score of 0

11.3.3.3 Graph layout/ graph embedding challenge for minimal graph with $\mathbb Z _4$ symmetry

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=310123

The minimal simple, connected graph with $\mathbb{Z}_4$ symmetry, aka 'square with tangled hats' graph, has $10$ vertices and $20$ edges. 
It's not in GraphData in Mathematica (yet...), but can be ... 
[graphics] [graphs-and-networks] [symmetry]
 

asked by Michael T https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=104815 Score of 3