12.9.1 Top new questions this week

12.9.1.1 DSolve gives solution that is not a solution
12.9.1.2 How to make RegionPlot3D draw facets accurately
12.9.1.3 Creation & Annihilation Operators with Non-Commutative Algebra Mathematica 14.3
12.9.1.4 Integration of multidimensional `DiracDelta[x]DiracDelta[y]` gives wrong result!
12.9.1.5 Why does this trigonometric sum show unexpected poles in Plot?
12.9.1.6 Points between which the region distance was measured
12.9.1.7 Special Flatten in ragged arrays
12.9.1.1 DSolve gives solution that is not a solution

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318898

I have the following code 
 DSolve[-(3/2) D[P[t, x], x] D[P[t, x], t] == D[P[t, x], t, x], P, {t,x}] 
 
which gives as a solution 
... 
[differential-equations] [bugs]
 
asked by mattiav27 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8822 Score of 9
answered by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 Score of 5
12.9.1.2 How to make RegionPlot3D draw facets accurately

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318842

I've been thinking about hexastix and I thought I would try to make some images in Mathematica, similar to this one which I took from Wikipedia: 
 
So, my first goal is to make a single infinite ... 
[graphics3d] [regions] [computational-geometry] [regionplot]
 
asked by David E Speyer https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1200 Score of 8
answered by azerbajdzan https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53172 Score of 9
12.9.1.3 Creation & Annihilation Operators with Non-Commutative Algebra Mathematica 14.3

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318857

I want to work with (mostly expand/simplify) expressions involving some creation & annihilation operators. 
Mathematica 14.3 now has the NonCommutativeAlgebra[] function which seems like it could ... 
[algebraic-manipulation] [ncalgebra] [version-14.3] [non-commutative-algebra]
                                                                                  

                                                                                  
 
asked by Mstislav Keldysh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=93185 Score of 7
answered by march https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=29734 Score of 10
12.9.1.4 Integration of multidimensional `DiracDelta[x]DiracDelta[y]` gives wrong result!

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318880

The integration of  DiracDelta[]  in two dimensions gives the expected result 
... 
[distributions]
 
asked by Ulrich Neumann https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53677 Score of 5
answered by azerbajdzan https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53172 Score of 3
12.9.1.5 Why does this trigonometric sum show unexpected poles in Plot?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318894

Given the following sum 
 Sum[Sin[x^2*(2*t - 1)*y]^2/Sin[2*x^2*y*t]^2, {t, 1, L - 1}] 
 
where $x\le L-2$ and $x$, $y$, and $t$ are all positive (non-zero) integers. ... 
[functions] [summation] [trigonometry] [singularity]
 
asked by Rob https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=66809 Score of 4
answered by Bob Hanlon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9362 Score of 3
12.9.1.6 Points between which the region distance was measured

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318896

 RegionDistance  is quite effective. But can we extract positions of points between which this distance was measured (without using other methods to recompute them)? ... 
[regions] [geometry] [distance]
 
asked by azerbajdzan https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=53172 Score of 4
answered by user64494 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7152 Score of 3
12.9.1.7 Special Flatten in ragged arrays

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=318863

I'm working on a project in the spirit of Wolframs Ruliad concept. 
A nested ragged arrays appear in the process e.g.  {0}, {0,{1}}, {{1}, {{0}, 1}}}  etc. 
And ... 
[list-manipulation] [replacement] [pattern-matching]
 
asked by lesobrod https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5950 Score of 4
answered by lericr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=84894 Score of 4