8.39.1 Top new questions this week

8.39.1.1 Mathematica for Theoretical Physics by Gerd Baumann : Henonmap
8.39.1.2 SortBy with a 2nd argument that specifies not to sort the list?
8.39.1.3 How to make this pipe network shape?
8.39.1.4 How to Partition List into sublists so that it orders down columns when placed into a Grid instead of across rows
8.39.1.5 Automatic scoping of input to function
8.39.1.6 How can I obtain this simplification of an expression?
8.39.1.7 How to select elements from a list of pairs based on first element belonging to a different list?
8.39.1.1 Mathematica for Theoretical Physics by Gerd Baumann : Henonmap

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=276596

I was following a solved problem from the book mentioned below on the Henon map. However, even after correcting that I still get an error on execution. I am unable to find the exact cause. 
 
... 
[plotting] [code-review] [compatibility]
 
asked by user84456 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=84456 Score of 9
answered by I.M. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=26815 Score of 13
8.39.1.2 SortBy with a 2nd argument that specifies not to sort the list?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=276697

One can specify the second argument of  SortBy  not to sub-sort ties, i.e. cases that have identical values according to the main sorting function. ... 
[functions] [sorting]
 
asked by István Zachar https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89 Score of 8
answered by Lukas Lang https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36508 Score of 9
8.39.1.3 How to make this pipe network shape?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=276715

I want to draw this shape in mathematica. I don't know what to start with. Can I use  BezierCurve ? Or should I try to form an equation that could end up in this ... 
[plotting] [graphics] [graphs-and-networks] [code-request]
 
asked by user84456 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=84456 Score of 7
answered by George Varnavides https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=41179 Score of 6
8.39.1.4 How to Partition List into sublists so that it orders down columns when placed into a Grid instead of across rows

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=276556

Partitioning a  List  into sub-lists and placing them directly into a Grid orders sub-lists across rows. Is there an idiot-proof built-in function or a simple ... 
[list-manipulation] [output-formatting] [sorting] [grid-layouts] [gird]
 
asked by Jules Manson https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=37721 Score of 6
answered by Vito Vanin https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=39633 Score of 3
8.39.1.5 Automatic scoping of input to function

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=276553

I'd like to write a function whose arguments contains symbols that are automatically localized, just like some built-in functions, like Sum.  Even better, I'd like to see the symbols' color change, to ... 
[scoping] [localization]
 
asked by Ben https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89206 Score of 5
answered by Lukas Lang https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36508 Score of 6
8.39.1.6 How can I obtain this simplification of an expression?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=276474

I saw this question at the Maple forum. 
The input is 
... 
[simplifying-expressions]
 
asked by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 Score of 5
8.39.1.7 How to select elements from a list of pairs based on first element belonging to a different list?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=276684

This is my very first question and I really appreciate this ability and thankful the community. 
I have two lists and need to select only those pairs from the first list, first element of which is ... 
[list-manipulation] [filtering] [conditional] [subset]
 
asked by Igor Binder https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89246 Score of 4