2.29 Thursday, May 7, 2020

2.29.1 Top new questions this week

‘Count‘ for ‘SparseArray‘

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=221160

Why does Count not work with SparseArrays, and is there any function I can use to replace it?

What would be an efficient workaround?

Example:

a=ConstantArray[0,{10},SparseArray]; 
Count[a,0] (*  ...

asked by Daniel https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=19534 9 votes

answered by thorimur https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=63584 8 votes

What is the best and most efficient way to curry?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=220972

Suppose I have a function with a signature like g[expr, _?(f), {1}, Heads -> False] 
and I want to access it as an operator by giving the first argument last. 
I see there are various ways of doing  ...

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

Mathematica and Excel

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=221155

I have a number of large data sets in Excel and .dat from OMEdit Modelica that then need to import some or all of it to Mathematica for manipulation and plotting. Importing the data is easy enough ...

asked by Chris B https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=58764 8 votes

answered by kglr https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=125 10 votes

Local variables in sums and tables - best practices?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=221079

Stumbled on Local variables when defining function in Mathematica in math.SE and decided to ask it here. Apologies if it is a duplicate - the only really relevant question with a detailed answer I ...

asked by https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=35000 8 votes

answered by WReach https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=142 5 votes

How can I make Mathematica solve this set of four equations?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=221082

I use Mathematica version 12.1 on Windows 10.

I have four equations in four unknowns.

Is there a trick to make Mathematica solve these?

I tried Solve and NSolve and it is not able to do it. ...

asked by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 8 votes

answered by J. M.’s technical difficulties https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5 7 votes

obtain properly formatted code from autogenerated package

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=220842

Overview: I have written a few mathematica packages, always using the method of writing my code in a mathematica notebook and letting mathematica autogenerate the .m package file. Currently I do not ...

asked by Wizard https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5033 8 votes

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

Why is StreamPlot plotting direction like this?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=221255

I am doing a StreamPlot and something seems wrong with the output.

  StreamPlot[{0, -(y - x)^3}, {x, -3, 3}, {y, -3, 3}] 
 
The plot is attached and I highlighted the issue in red 
 
Shouldn't the  ...

asked by Moo https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=36141 7 votes

answered by user2432923 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=61643 5 votes

2.29.2 Greatest hits from previous weeks

My Girlfriend is going to prison...Save her with Math

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=135937

Salacious title, but true story.

 dmethyl1 = { 
      {0, 0}, 
      {.25, 1}, 
      {.5, 7}, 
      {1, 26}, 
      {1.5, 40}, 
      {2, 45}, 
      {2.5, 45}, 
      {3, 44}, 
      {3.5, 44}, 
      {4,  ...

asked by Prisoners Dilema https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=46025 42 votes

answered by bobthechemist https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7167 23 votes

Calculate the 2D Fourier transform of an Image

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=29203

I am new to Mathematica, and using version 8.0.

I would like to calculate the 2D Fourier Transform of an Image with Mathematica and plot the magnitude and phase spectrum, as well as reconstruct the ...

asked by user8727 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8727 14 votes

answered by Nasser https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=70 32 votes

Help find a bright object on Mars!

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=11819

In today’s news, scientists found a bright object on one of Curiosity’s photos (it’s near the bottom of the picture below). It’s a bit tricky to find - I actually spent quite some time staring at the ...

asked by Victor K. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1351 197 votes

answered by Niki Estner https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=242 255 votes

Are you interested in purchasing David Wagner’s "Power programming with Mathematica"?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=16485

I recently contacted McGraw-Hill to see if they have a mechanism in place for printing out-of-print books that are still of interest. Specifically, I asked about "Power programming with Mathematica" ...

asked by Todd Allen https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=249 158 votes

answered by Todd Allen https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=249 232 votes

Even Fibonacci numbers

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=37266

Today, I found the Euler Project. Problem #2 is

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, ...

asked by xyz https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9627 34 votes

answered by rcollyer https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=52 46 votes

What does # mean in Mathematica?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=19035

I asked Mathematica to compute the following

Solve[c (1-x)^2-x^(1/4) == 0, x] 
 
 
and it returned this: 
 
  x = Root[#1^8 c^4 - 8 #1^7 c^4 + 28 #1^6 c^4 - 56 #1^5 c^4 + 70 #1^4 c^4 - 56 #1^3 c^4 + 28  ...

asked by ronanymous https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5730 37 votes

answered by Dr. belisarius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=193 63 votes

How to ask Mathematica to imitate Andy Warhol’s pop-art painting?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=59132

I tried to ask Mathematica to imitate Andy Warhol, let it convert a Marilyn Monroe’s portrait so that it looks like Warhol’s world famous pop-art painting. However, the result shown below is far from ...

asked by Putterboy https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=16069 50 votes

answered by Dr. belisarius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=193 65 votes

2.29.3 Can you answer these questions?

How to specify AxesOrigin for DateListPlot?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=221222

I would like to generate a plot with the y axis on the graph. In a "normal" numeric plot I do this using the AxesOrigin option. How to I specify the crossing point in a DateListPlot?

Here’s the MWE ...

asked by jmm https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=57731 1 vote

How to create a seek bar with Slider

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=221284

I am trying to create a simple audio player but I am stuck at designing the seek bar. I am using the AudioStream framework.

After loading music in a variable stream, I can access its position using ...

asked by Sâu https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=67944 1 vote

How can I get a plot of "surface area coverage" of a parametric plot?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=220846

I have a parametric function defined by the x and y functions:

 
x = r*Cos[w_0*t - w_L*t] + 
  z*Cos[w_P*t - w_L*t] 
 
y = r*Sin[w_0*t - w_L*t] + 
  z*Sin[w_P*t - w_L*t]

I can change the variables ...

asked by Cameron_3298 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72418 1 vote

answered by MarcoB https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=27951 0 votes