7.23.1 Top new questions this week

7.23.1.1 Is there a way to replace only once if possible by trying the rules sequentially in order?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=250454

Is there a  ReplaceOnce  which does only one replacement if possible by trying the rules sequentially in order. Consider the following as an example: 
... 
[replacement]
 

asked by user13892 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13892 9 votes

answered by kglr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=125 8 votes

7.23.1.2 How can I make a region for boundary conditions for a 3D geometry?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=250648

I sometimes work with pipes which can take up complicated positions in 3D geometries. Here is a minimum working example of what I am trying to do. 
Suppose I want to mesh and calculate vibration ... 
[finite-element-method]
 

asked by Hugh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12558 7 votes

answered by Tim Laska https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=61809 8 votes

7.23.1.3 Hessian matrix with D and Sum Method->"Procedural"

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=250529

Having just discovered  Sum 's  Method -> "Procedural" , I've quickly run into what seems to be a bug in calculating a ... 
[calculus-and-analysis] [bugs] [summation]
 

asked by Chris K https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=6358 7 votes

answered by Michael E2 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=4999 3 votes

7.23.1.4 An odd Grid style

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=250667

Consider the following grid 
 n = 10; 
Grid[{{"Matrix", SpanFromLeft}, 
RandomInteger[n, n], RandomInteger[n, n]}, 
Frame -> All, Alignment -> Center] 
 ... 
[list-manipulation] [style] [grid-layouts] [grid-lines] [grid-mathematica]
 

asked by sam wolfe https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=64001 6 votes

answered by kglr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=125 6 votes

7.23.1.5 How to supply argument to pure function when slot is already defined?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=250575

Here's an example of a pure function: 
 3^# > 100 & 
 
I can supply any value I please to the function, by placing that value after the prefix. E.g.: 
... 
[pure-function] [slot] [arguments]
 

asked by theorist https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=45215 6 votes

answered by Leonid Shifrin https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=81 8 votes

7.23.1.6 Append vs AppendTo

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=250474

According to the documentation  AppendTo[s,elem]  is equivalent to  s = Append[s,elem] . 
But then 
... 
[evaluation]
 

asked by freddy90 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=45339 6 votes

answered by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 7 votes

7.23.1.7 Meshing Accuracy in 3d

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=250661

The Element Mesh Generation tutorial describes how good mesh accuracy is achieved through adjusting boundary nodes so they match the region boundary.  This is illustrated with this example: 
... 
[finite-element-method] [mesh]
 

asked by Jack McInerney https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=20201 5 votes

answered by user21 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=18437 5 votes