1.6 Thursday, April 15, 2021

1.6.1 Top new questions this week

Is there a neat code to swap elements of a list?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244314

I want to swap the list to make a new list as follows. The code works but I’m wondering if there is a neat code, or an elegant way to do this.

asked by anhnha https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=18805 9 votes

answered by kirma https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=3056 10 votes

Stokes equations in 2D with traction boundary conditions

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244482

This is a follow-up to a previous question (see here). We would like to solve the two-dimensional Stokes equations using the FEM package in Mathematica, when we prescribe traction boundary conditions. ...

asked by Alex R https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=78043 7 votes

answered by Oleksii Semenov https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=63028 3 votes

Transform a number to a factorial

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244566

I came across the need to transform a number into a factorial n, with positive integer n. I have searched in the MMA information but I can’t find anything like that. I imagine an input, which verifies ...

asked by zeros https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=26849 7 votes

answered by Bob Hanlon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9362 6 votes

Stopping condition for FindMinimum / FindMaximum

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244313

This seems like it should be a simple question – but I am looking to use a "home made" stopping condition with FindMaximum, while evaluating a very complex function. Printing out the ...

asked by Richard E https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=79342 7 votes

answered by Daniel Huber https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=46318 8 votes

Efficiently compute Minkowski sum of a 2D Region and a Disc of radius r?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244565

Given a 2D Mathematica Region, e.g. A = Region[RegionDifference[Disk[{0, 0}, 2], Disk[{2, 0}, 1]]], how can I grow the region by an arbitrary radius r? For example, ...

asked by Aaron T. Becker https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=76690 6 votes

answered by cvgmt https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72111 5 votes

Random orthogonal matrix

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244316

Is there a way to generate real random orthogonal matrices in mathematica? If Q is an orthogonal matrix, it’s properties are

asked by Jasmine https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=73364 6 votes

answered by Henrik Schumacher https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=38178 9 votes

Detecting patterns in a graph network

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244592

If we create a random graph

Chop[LowerTriangularize[RandomReal[{-1, 1}, {10, 10}], -1], 0.6] /.0 -> \[Infinity] // MatrixForm 
WeightedAdjacencyGraph[%]

How can ...

asked by Teabelly https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=56986 5 votes

answered by Szabolcs https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12 6 votes

1.6.2 Greatest hits from previous weeks

What do the X and Y axis stand for in the Fourier transform domain?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=85139

In Wolfram Mathematica the function Fourier has the following declaration

Fourier[list]

And after a list is given to the ...

asked by user253956 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=29958 27 votes

answered by Hugh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12558 61 votes

Plot, extract data to a file

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=19859

I need to save data that Mathematica uses inside the Plot command. The format that I would like to have is:

x1 y1 
x2 y2

asked by molkee https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5097 30 votes

answered by Mr.Wizard https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=121 47 votes

Get a "step-by-step" evaluation in Mathematica

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=148

Is it possible in Mathematica to get a step-by-step evaluation of some functions; that’s to say, outputting not only the result but all the stages that have led to it? If so, how does one do it?

asked by Cydonia7 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=44 131 votes

answered by J. M.’s ennui https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 109 votes

How to add a vertical line to a plot

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=3561

In the plot below I would like to add two vertical lines at \(x = \frac {\pi }{15} \pm \frac {1}{20}\). How can I do that?

asked by sjdh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=515 64 votes

answered by Ajasja https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=745 83 votes

Selecting every n-th element from a list

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=64003 I have a list:

data = {4, 5, 7, 8, 9, 5, 3, 2, 1, 2, 13, 12};

I want to take those elements in the list which are located at equal distances, say, every third ...

asked by Suro https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=20003 37 votes

answered by Szabolcs https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12 34 votes

How to graph a sphere with cartesian equations?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=24169

I’m new to Mathematica and I need to ask how to graph a sphere, cylinder, etc.. using cartesian equations.

For example in sphere’s case \(x^2+y^2+z^2=1\)

I tried to use ...

asked by German https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7145 7 votes

answered by Dr. belisarius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=193 13 votes

Conversion of Sine to Cosine

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=67521

I’m solving equations with many Cosines and Sines. And I want to convert all the Sines to Cosines using trigonometric formulas such as cos(x)=sin(x+pi/2). How can I do this?

asked by YongCheol Kwon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=23041 4 votes

answered by Sjoerd C. de Vries https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=57 2 votes

1.6.3 Can you answer these questions?

RandomInstance of GeometricScene producing unexpected result

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244335

Consider the following scene as an example:

asked by user13892 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=13892 1 vote

Solving an ordinary differential equation with boundary condition at infinity

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244342

I want to solve the following differential equation  f''[z] + (1/z)*f'[z] - f[z] + f[z]^3 == 0

subject to the boundary conditions

asked by HeitorGalacian https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=73726 1 vote

answered by Mariusz Iwaniuk https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=26828 0 votes

How to use ScalingFunctions with Graphics ChartElements

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=244387

How to draw spheres with BubbleChart with a reversed vertical axis? The 3rd example shows the problem (empty plot), likely caused by the transformation, but how to correct it?

asked by HuibH https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70256 3 votes