9.37.1 Top new questions this week

9.37.1.1 Mimicking Günther Uecker's nail art
9.37.1.2 Why doesn't Mathematica recognise two integrals as equal?
9.37.1.3 Apply function to all first arguments of a nested list of rules
9.37.1.4 Make association with deepest rules from nested association
9.37.1.5 Numerical solution of second-order linear hyperbolic PDE
9.37.1.6 Implementation of SINC filter using Integrate results in incorrect output
9.37.1.7 How to produce a Calder mobile?
9.37.1.1 Mimicking Günther Uecker's nail art

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292071

One of my favourite contemporary artists is Günther Uecker (born 13 March 1930 in Crivitz, Germany). He uses hammer and nails to create  VectorPlot -like structures. ... 
[plotting] [graphics] [vector]
 
asked by eldo https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=14254 Score of 8
answered by vindobona https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=58868 Score of 7
9.37.1.2 Why doesn't Mathematica recognise two integrals as equal?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292137

The following expression 
$$\int_{0}^{t} f(t_0) \,dt_0 - \int_{0}^{t} f(t_1) \,dt_1 = 0$$ 
is zero because it is just a change of integration variable. 
Why doesn't Mathematica give zero in this case? 
<... 
[calculus-and-analysis] [simplifying-expressions]
 
asked by Luca https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=85902 Score of 7
answered by I. C. Lin https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=94800 Score of 4
9.37.1.3 Apply function to all first arguments of a nested list of rules

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292197

Currently, I have a nested list of rules of the form 
 lst1={1->a,2->{3->c,4->d,5->{6->f,7->{8->h,...}}}} 
 
(where I don't know the length of ... 
[list-manipulation] [replacement] [pattern-matching] [nested-function]
 
asked by cstover https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=20079 Score of 5
answered by Syed https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=81355 Score of 5
9.37.1.4 Make association with deepest rules from nested association

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292009

I want to extract only the deepest level of association in a nested associations. 
An example of input data is 
... 
[associations]
 
asked by user14061 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=14061 Score of 5
answered by lericr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=84894 Score of 5
9.37.1.5 Numerical solution of second-order linear hyperbolic PDE

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292108

(I'm also searching for analytical solutions to this PDE; check the bountied questions here and here if you have any ideas) 
 
I'm trying to find the numerical solution of the following 2D second-order ... 
[differential-equations] [finite-element-method]
 
asked by pp.ch.te https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=48527 Score of 4
answered by Ulrich Neumann https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53677 Score of 1
9.37.1.6 Implementation of SINC filter using Integrate results in incorrect output

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292127

Bug introduced in 6.0, persisting through 13.3.1. 
 
This is SINC filter, integrate $|H|^2$ from $-\pi/2$ to $\pi/2$. 
MMA CODE, Result = 7.27956e-12 
... 
[calculus-and-analysis] [numerical-integration] [bugs] [complex]
 
asked by Ring https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=82659 Score of 4
answered by xzczd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1871 Score of 8
9.37.1.7 How to produce a Calder mobile?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292212

Alexander Calder (1898 - 1976) was an American artist known for for his mobiles and his public sculptures. 
Here are two examples of his mobiles which I want to approximately reproduce with ... 
[plotting] [graphics] [graphs-and-networks]
 
asked by eldo https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=14254 Score of 3
answered by ydd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72953 Score of 2