9.2.1 Top new questions this week

9.2.1.1 Optimize search for rational numbers on unit circle?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=278250

Crossposted:https://community.wolfram.com/groups/-/m/t/2763509 
 
I'd like to classify rational numbers on a unit circle by the following property: number of digits in the denominator. It relates to an ... 
[performance-tuning] [diophantine-equations]
 

asked by Vitaliy Kaurov https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13 Score of 18

answered by Henrik Schumacher https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=38178 Score of 18

9.2.1.2 FEM doesn't output exactly the same solution for exactly the same code?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=278227

Consider this toy example: 
... 
[differential-equations] [finite-element-method] [implementation-details]
 

asked by xzczd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1871 Score of 12

answered by xzczd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1871 Score of 10

9.2.1.3 Compare values in two lists and assign new value to index if entries match

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=278431

Assume I have two lists, for example the following: 
 list1 = {1, 2, 1, 3, 2}; 
list2 = {{1, a}, {3, c}, {2, b}}; 
 
I would like to compare each element of ... 
[list-manipulation]
 

asked by mrkhlavkalash https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89925 Score of 9

answered by bmf https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=85558 Score of 11

9.2.1.4 How to do integer interval arithmetic?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=278243

How to calculate union, intersection and complement of integer intervals without actually generating all integers in the range and perform set-arithmetic ( Union , <... 
[sets] [intervals] [discrete]
 

asked by István Zachar https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89 Score of 8

answered by rhermans https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=10397 Score of 2

9.2.1.5 2D cross-section of ParametricPlot3D

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=278408

Now I'm trying to get the two-dimensional cross-section from ParametricPlot3D, the details of this question are as follows 
As an example, here is a parametric equation: x=x(u,v)    y=y(u,v)     z=z(u,... 
[plotting] [parametric-functions]
 

asked by zhongwt https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89873 Score of 7

answered by Greg Hurst https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4346 Score of 11

9.2.1.6 How to Obtain Complete List of Properties

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=278409

I am working with Matrix Market matrices in Mathematica (specifically GEMAT12), and I saw from other posts that you call properties of a variable exemplified below: 
... 
[variable]
 

asked by Chloe https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=82544 Score of 7

answered by rhermans https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=10397 Score of 9

9.2.1.7 Most convenient way to visualize the internal structure of a three-dimensional manifold

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=278445

Let's say we have a 3D spherical shell specified by the command: 
 Regionplot3D[1/2<x^2+y^2+z^2<1,{x,-2,2},{y,-2,2},{z,-2,2},BoxRatios->Automatic] 
 
When ... 
[plotting] [graphics3d] [projection]
 

asked by dtn https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=67019 Score of 6

answered by Daniel Huber https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=46318 Score of 8