12.7.1 Top new questions this week

12.7.1.1 Extracting analemma from series of sunset photos
12.7.1.2 When do we need the Update[] function?
12.7.1.3 System of differential equations with overdetermined boundary conditions
12.7.1.4 Region with Sign in its definition kills the kernel
12.7.1.5 How to convert PDE into ODE?
12.7.1.6 Problem with IncludePoints in ToElement Mesh
12.7.1.7 Why won't Wolfram Engine perform this integration?
12.7.1.1 Extracting analemma from series of sunset photos

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318744

This is a recreational question. I would value better approaches. 
Aim 
I found the following image on substack. 
 
I wondered whether it would be possible to show the analemma from these images. 
I don't ... 
[image-processing] [image]
 
asked by ubpdqn https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1997 Score of 17
answered by azerbajdzan https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53172 Score of 12
12.7.1.2 When do we need the Update[] function?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318748

Probably a hard question, but I think it's better to have a separate post for it. 
For now, no one has found a general rule determining when  Update  is necessary ... 
[evaluation] [core-language]
 
asked by xzczd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1871 Score of 12
answered by Michael E2 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4999 Score of 8
12.7.1.3 System of differential equations with overdetermined boundary conditions

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318747

I am trying to verify the results in the paper Self-dual Chern-Simons solitons by R. Jackiw, Kimyeong Lee and Erick J. Weinberg, where they arrive at the expressions $g'(r)=\frac{a(r)g(r)}{r}$ and $\... 
[differential-equations] [finite-element-method] [boundary-condition-at-infinity] [singularity] [paper-reproduction]
 
asked by MrClapton https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=116058 Score of 7
answered by xzczd https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1871 Score of 9
12.7.1.4 Region with Sign in its definition kills the kernel

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318737

This works: 
... 
[regions] [kernel] [crash]
 
asked by azerbajdzan https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53172 Score of 7
answered by cvgmt https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72111 Score of 5
12.7.1.5 How to convert PDE into ODE?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318749

I have a function J(x,y) = J(y,x) which satisfies the following PDEs with $\theta_x = x \frac{\partial}{\partial x}$ and $\theta_x = y \frac{\partial}{\partial y}$ 
 
$(1+\theta_x) (1+\theta_x+\theta_y)(... 
[differential-equations] [calculus-and-analysis]
 
asked by Epsilon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=71940 Score of 3
answered by yarchik https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9469 Score of 4
12.7.1.6 Problem with IncludePoints in ToElement Mesh

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318738

In a finite element code I whish to use  "IncludePoints"  in  ToElementMesh  and I get a failure. Here is a minimum ... 
[finite-element-method] [mesh] [opencascade]
 
asked by Hugh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12558 Score of 3
answered by user21 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=18437 Score of 6
12.7.1.7 Why won't Wolfram Engine perform this integration?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318764

I want to find the exact value of this definite integral in terms of  c  and  q  with the following assumptions: 
... 
[calculus-and-analysis]
 
asked by Lawton https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=92961 Score of 2
answered by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 Score of 7