2.19 Thursday, July 23, 2020

2.19.1 Top new questions this week
2.19.2 Greatest hits from previous weeks
2.19.3 Can you answer these questions?

2.19.1 Top new questions this week

How to rewrite a tensor as a matrix
Breaking "Functional Loops" and Doing Lazy Evaluation In Mathematica
Hexadecimal bytes as variable converted to binary bits
Kernel starts up very slowly on Linux
How to decompose a list of n-tuples into a union of Cartesian products
Mathematica emits a beep after any evaluation - how to remove it?
Prony series with a large number of terms

How to rewrite a tensor as a matrix

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226089 I put

{TensorProduct[{1, 0}, {0, 1}, {0, 1}, {0, 1}, {0, 1}]}/Sqrt[2]//MatrixForm 
and I got 
$$ 
\left( 
\begin{array}{cc} 
 \left( 
\begin{array}{cc} 
 \left( 
\begin{array}{cc} 
 0 & 0 \\ 
 0 & 0 \\

asked by Moeki https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=73815 12 votes

answered by Suba Thomas https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5998 9 votes

Breaking "Functional Loops" and Doing Lazy Evaluation In Mathematica

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226334

Alright, so this is a question about the functional way to break a for/while loop. Since we’re on the Mathematica SE, I’m interested in the ways a Mathematica vet would handle this, however the ...

asked by dskeletov https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=34831 8 votes

answered by flinty https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72682 6 votes

Hexadecimal bytes as variable converted to binary bits

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226171

I am working with hexadecimal bytes but need to shift them into lists of binary bits for a few operations and then back again. For example, I would like C12B to turn into ...

asked by toothandsticks https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=73837 8 votes

answered by Hausdorff https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=73380 9 votes

Kernel starts up very slowly on Linux

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226128

V 12.1.1, starting a kernel, e.g. by entering wolframscript in the shell, takes 
an unexpectedly long time (~5 min, the time elapsed between pressing Enter and 
the showing-up of In[1] := ); but the  ...

asked by https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12924 8 votes

answered by Ordinary users68 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=42417 5 votes

How to decompose a list of n-tuples into a union of Cartesian products

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226294

I have a list with all elements at the same level

{ 
    {a, d}, {a, e}, {a, f}, 
    {b, d}, {b, e}, {b, f}, 
    {c, d}, {c, e}, {c, f}, 
    {x, t}, {x, q} 
}

How can I transform this to a list of ...

asked by Martin Leung https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=73880 7 votes

answered by yarchik https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9469 4 votes

Mathematica emits a beep after any evaluation - how to remove it?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226316

Without any obvious reason Mathematica started to emit a beep after each evaluation, even when it is error free. Why is that, and how can I turn it off? I tried restarting Mathematica to no avail, and ...

asked by Jxx https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=68480 6 votes

answered by Ordinary users68 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=42417 6 votes

Prony series with a large number of terms

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226327

A Prony series is similar to a Fourier series but can have fewer terms. It takes the form \(\sum _{i=1}^{M} A_i e^{\sigma _i t} \cos \left (\omega _i t+\phi _i\right )\) Note that unlike Fourier series ...

asked by Hugh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12558 6 votes

2.19.2 Greatest hits from previous weeks

Is there an open source implementation of Mathematica-the-language?
Image processing: Floor plan - detecting rooms’ borders (area) and room names’ texts
How to make Jacobian automatically in Mathematica
Skip header lines on import
How to find the position of elements in a list satisfying criteria
How to make an inkblot?
How to generate a random snowflake

Is there an open source implementation of Mathematica-the-language?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=4454

I’ve seen questions before such as "What is the best open-source equivalent for Mathematica?", but that specific question (and that line of inquiry in general) cares more about the computer algebra ...

asked by sblom https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=178 121 votes

answered by Simon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=34 83 votes

Image processing: Floor plan - detecting rooms’ borders (area) and room names’ texts

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=19546

Here is a simple building floor plan. I would like to derive the rooms as (rectangular) components and the names of the rooms. This is very common representation of building floor plans.

The ...

asked by s.s.o https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=840 63 votes

answered by Niki Estner https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=242 58 votes

How to make Jacobian automatically in Mathematica

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=5790

If we have two vectors, \(a\) and \(b\), how can I make Jacobian matrix automatically in Mathematica?

$$ a=\left( 
\begin{array}{c} 
 x_1^3+2x_2^2 \\ 
 3x_1^4+7x_2 
\end{array} 
\right);b=\left(

asked by George Mills https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1012 38 votes

answered by Jens https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=245 50 votes

Skip header lines on import

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=50718

When importing a data file what are the comment symbols for Mathematica? That is, given a file like this

blabla bulbul

1 2 6 54 7 ...

what symbol do I have to put in front of header lines so ...

asked by MaxJ https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=14687 20 votes

answered by george2079 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=2079 18 votes

How to find the position of elements in a list satisfying criteria

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=180

Say I have a list x=2,4,6,8,10 and I want to find out the positions of the elements that are greater than 7.

Select[x, #>7&] gives the elements themselves, and Position[x,8] gives the  ...

asked by PeterR https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=140 65 votes

answered by J. M.’s technical difficulties https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=50 62 votes

How to make an inkblot?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=3345

How to effectively create a polygon that looks like a realistic inkblot? So far, I could come up with this (borrowing from Ed Pegg Jr.’s Rorschach demonstration):

RandomBlot[num_, opts___] :=  ...

asked by István Zachar https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=89 86 votes

answered by Sjoerd C. de Vries https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=57 51 votes

How to generate a random snowflake

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=39361

’Tis the season... And it’s about time I posed my first question on Mathematica Stack Exchange. So, here’s an holiday quest for you Graphics (and P-Chem?) gurus.

What is your best code for generating ...

asked by Peltio https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=6745 140 votes

answered by Silvia https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=17 181 votes

2.19.3 Can you answer these questions?

How to write this piece of code without AppendTo
Solving a cubic equation in mathematica
Using Select for lattice points

How to write this piece of code without AppendTo

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226081

I am trying to fill a vector starting from component 11 from another vector, I use this code:

Do[AppendTo[xp, x[[i + 10]]], {i, 1, 99982}]

How can I fill xp without using ‘AppendTo’?

asked by mattiav27 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8822 1 vote

Solving a cubic equation in mathematica

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226231

I am trying to solve a cubic equation using Mathematica of a rather complicated expression say \(f(r,\beta ,\theta )\) , and in terms of \(r\) the maximum degree term that appears is of degree \(3\) so I ...

asked by Wubba lubba dub dub https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70072 1 vote

Using Select for lattice points

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=226130

I know how to use Select to generate a list of numbers which satisfy a certain condition. However, I am not sure how to do this for points (specifically 2-tuples) rather than numbers. What I am trying ...

asked by Descartes Before the Horse https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=69355 1 vote