4.1 Tuesday, December 26, 2017

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Top new questions this week: 
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[How fast is my fidget spinner spinning? A sound experiment!] https://mathematica.stackexchange.com/questions/162303/how-fast-is-my-fidget-spinner-spinning-a-sound-experiment

I would like to measure how fast my 6-bladed fidget spinner spins. To do so, after giving it a hard spin, I gently touch the spinner with a wooden stirring stick to create a buzzing sound which ...

- asked by Miladiouss (17 votes), answered by Miladiouss (10 votes)

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[Sub-packages and auto-completion] https://mathematica.stackexchange.com/questions/162386/sub-packages-and-auto-completion

Cross-posted on Wolfram Community

I have a Mathematica application that consists of two sub-packages, corresponding to the contexts foo‘ (foo.m) and foo‘b‘ (b.m). Some of the definitions in foo.m ...

- asked by Szabolcs (11 votes), answered by b3m2a1 (2 votes)

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[Why does Cases not find a match to the pattern using nˆ  _. when n is a number other than 1?] https://mathematica.stackexchange.com/questions/162559/why-does-cases-not-find-a-match-to-the-pattern-using-n-when-n-is-a-number-oth

I am not good in patterns in Mathematica, and so can’t figure what I am doing wrong.

This example works, when the exponent is 1

ClearAll[y,x,n] 
Cases[{( y[x]/x)^1}, (y[x]/x )^(n_.) :> n]

But ...

- asked by Nasser (10 votes), answered by m_goldberg (9 votes)

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[How to make an Epilog moveable with drag and drop] https://mathematica.stackexchange.com/questions/162572/how-to-make-an-epilog-moveable-with-drag-and-drop

I would like to make an Epilog moveable. For example, the following code generates a Manipulate with a framed pane containing some notes. I would like the user to be able to move those notes anywhere ...

- asked by Michael McCain (8 votes), answered by Mike Honeychurch (9 votes)

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[Map every second element of a list] https://mathematica.stackexchange.com/questions/162334/map-every-second-element-of-a-list

I’ve loaded a CSV:

Colors = Import[ 
  "d:\\bitbucket\\diversity\\data\\nlcd\\nlcd-colors.csv", "CSV"] 
{{0., " 0.00000000000 0.00000000000 0.00000000000"}, {11., 
  " 0.27843137255 0.41960784314  ...

- asked by pnz (8 votes), answered by Kuba (13 votes)

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[Table of precedence values for all System‘ symbols] https://mathematica.stackexchange.com/questions/162474/table-of-precedence-values-for-all-system-symbols

Has anyone created a table listing the precedences for all symbols? Also, it would be nice if there were a function that for a given precedence value or interval, returned all the symbols with that ...

- asked by Carl Woll (7 votes), answered by Carl Woll (8 votes)

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[How to make a custom DynamicImage which support mouse wheel and show pixel value?] https://mathematica.stackexchange.com/questions/162311/how-to-make-a-custom-dynamicimage-which-support-mouse-wheel-and-show-pixel-value

The built-in DynamicImage just click the plus sign or minus sign to rescale the image. I have to say click is a not very good operation. Could we make the custom DynamicImage which support the mouse ...

- asked by yode (7 votes), answered by M.R. (3 votes)

================================== Greatest hits from previous weeks: ==================================

[xkcd-style Plots] https://mathematica.stackexchange.com/questions/11350/xkcd-style-plots

I received an email to which I wanted to respond with a xkcd-style graph, but I couldn’t manage it. Everything I drew looked perfect, and I don’t have enough command over PlotLegends to have these ...

- asked by Amatya (553 votes), answered by Simon Woods (409 votes)

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[Why round to even integers?] https://mathematica.stackexchange.com/questions/2116/why-round-to-even-integers

According to the Mathematica help:

Round rounds numbers of the form x.5 toward the nearest even integer.

For example: 
 
Round[{0.5, 1.5, 2.5, 3.5, 4.5}] 
 
 
gives 
 
{0, 2, 2, 4, 4}

What’s the ...

- asked by wxffles (69 votes), answered by Per Alexandersson (43 votes)

================================== Can you answer these? ==================================

[How can I check that a graph is edge weighted, fast?] https://mathematica.stackexchange.com/questions/162391/how-can-i-check-that-a-graph-is-edge-weighted-fast

I need to check if a graph is edge-weighted while maintaining good performance.

This should be an easy task, but it is not. It is a good example of why it is so terribly frustrating to work with ...

- asked by Szabolcs (5 votes)

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[contour of inside of a volume] https://mathematica.stackexchange.com/questions/162306/contour-of-inside-of-a-volume

I have the following volume:

RegionPlot3D[-j^2*y^2 + j*l < 11, {l, 0, 10}, {j, 0, 10}, {y, 0, 1}]

However, I am not able to obtain a 2D graph from it (contour), which shows the region inside the ...

- asked by Darrin Cope (1 vote)

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[Finsler or Lagrange geometry package?] https://mathematica.stackexchange.com/questions/162489/finsler-or-lagrange-geometry-package

I was wondering if there exist any packages or examples of work on Finsler-Lagrange geometry. I need it to do symbolic calculations, as for example calculations of non-linear connection coefficients, ...

- asked by Athis Startis (1 vote)