8.33.1 Top new questions this week

8.33.1.1 2016 Putnam B6 difficult summation problem

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=274570

Problem B6 on the 2016 Putnam exam is to calculate: 
$$\sum\limits_{k=1}^\infty \left( \frac{(-1)^{k-1}}{k} \sum\limits_{n=0}^\infty \frac{1}{k 2^n + 1} \right)$$ 
The direct approach 
... 
[summation]
 

asked by David G. Stork https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9735 Score of 11

answered by Mariusz Iwaniuk https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=26828 Score of 16

8.33.1.2 Detecting Hexagonal Components in Images

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=274402

I am trying to detect and characterize the size, orientation, and centroid of nearly perfect hexagonal features in images. The built-in  MorphologicalComponents  ... 
[image-processing]
 

asked by OpticsMan https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=58442 Score of 7

answered by Domen https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=75628 Score of 7

8.33.1.3 How to create a matrix of paired values from two matrices?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=274591

I have two matrices. They are, 
 m1={{a,b},{c,d}}; 
m2={{w,x},{y,z}}; 
 
I want to create a matrix of paired values that looks like this, 
... 
[list-manipulation] [map]
 

asked by desla.slade https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=74848 Score of 6

answered by bmf https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=85558 Score of 9

8.33.1.4 Why does DSolve spit out Part::partw warning?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=274571

Bug introduced in 13.1. 
 
Submitted to WRI. CASE  ID [CASE:4975479]. 
 
I was looking at this question. 
In V 13.1 I get an internal error which the above question does not mention so I assume it is a ... 
[differential-equations] [bugs] [version-13.1]
 

asked by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 Score of 6

answered by Michael E2 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4999 Score of 4

8.33.1.5 How do I include additional kinds of boxes that are Tab-selectable

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=274431

Observe that  "PlaceHolder"  and  InputFieldBox  are known by the FE to respond to pressing the Tab key: 
... 
[front-end] [gui-construction] [undocumented] [boxes] [eventhandler]
 

asked by QuantumDot https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=2048 Score of 6

answered by Kuba https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5478 Score of 4

8.33.1.6 Collect terms with the same denominator

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=274659

I have an expression 
$$\frac{A}{x}+\frac{A_2}{x^2}-\frac{D_2}{x}+\frac{C_2}{x^2}++\frac{F_2}{x^3}+\frac{I_2}{x^2y}+\frac{U_2}{y^2x}+\frac{Z_3}{x^2y}+\frac{J_2}{y^2x}+\cdots$$ 
and I am looking for a ... 
[sorting]
 

asked by jojo123456 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=67901 Score of 5

answered by Bob Hanlon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9362 Score of 3

8.33.1.7 How to prove this algebraic identity?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=274592

I mean 
$$\forall z \in \mathbb C\left(\ \left| \sqrt{z^2-1}-z\right| +\left| z+\sqrt{z^2-1}\right| =| z-1| +| z+1|\right ) .$$ 
The command 
... 
[simplifying-expressions] [complex]
 

asked by user64494 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7152 Score of 5

answered by ulvi https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1714 Score of 9