4.8 Tuesday, October 31, 2017

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Top new questions this week: 
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[Implementing a planetary terrain generation algorithm] https://mathematica.stackexchange.com/questions/158843/implementing-a-planetary-terrain-generation-algorithm

From this (now deleted) question I found this site where the author discusses a simple technique for random terrain generation on a sphere.

The method discussed is as follows:

start with a ...

- asked by b3m2a1 (18 votes), answered by b3m2a1 (19 votes)

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[Performance of Select] https://mathematica.stackexchange.com/questions/158583/performance-of-select

I have a data set of about 4*10^6 3d-coordinates.

From this volume I am sequentially selecting coordinates along one axis and manipulating this subset.

My question: can the Select function be ...

- asked by mrz (15 votes), answered by kglr (23 votes)

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[Create a simple split tree] https://mathematica.stackexchange.com/questions/158858/create-a-simple-split-tree

I am trying to create a simple split tree.

The growth should be only upwards, the vertical element length constant (1), the size of the horizontal bars should be halved in each iteration and the ...

- asked by Niki (12 votes), answered by m_goldberg (10 votes)

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[Easy printing of executable code] https://mathematica.stackexchange.com/questions/158901/easy-printing-of-executable-code

I’m working on a package that has functions that call other existing and packaged functions. I’d like a way to output what some of those key calls are, so users can see what’s happening under the ...

- asked by Chris K (9 votes), answered by Szabolcs (10 votes)

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[Two bouncing balls in 1 dimension, issues with two different methods?] https://mathematica.stackexchange.com/questions/158857/two-bouncing-balls-in-1-dimension-issues-with-two-different-methods

I’m trying to simulate 2 balls with the same mass and diameter bouncing one on top of another under gravity, see the illustration below (not ideal, but this is the best result I’ve got so far, the ...

- asked by Yuriy S (8 votes), answered by b3m2a1 (7 votes)

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[Receive macOS notification when evaluation finishes] https://mathematica.stackexchange.com/questions/158898/receive-macos-notification-when-evaluation-finishes

Is Mathematica able to communicate with macOS’s native Notification Center in order to notify me if an evaluation finishes in any of my open notebooks?

I’m looking for a solution similar to this one ...

- asked by Casimir (8 votes), answered by Szabolcs (12 votes)

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[Why does repeated export of JPG-Images consume all memory?] https://mathematica.stackexchange.com/questions/158690/why-does-repeated-export-of-jpg-images-consume-all-memory

I was looking in the history of asked questions for similar questions, but none of the alike questions answered my problem sufficiently. So I ask nevertheless.

My system memory is leaked by simple ...

- asked by sacratus (8 votes)

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

[Is it possible to draw this figure using Mathematica?] https://mathematica.stackexchange.com/questions/110848/is-it-possible-to-draw-this-figure-using-mathematica

The figure is

See the how-to video or a speeded-up GIF.

I believe it should be possible to draw this figure programmatically using some Random function, but I’m rather new to Mathematica, so I ...

- asked by AccidentalFourierTransform (62 votes), answered by M.R. (87 votes)

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[Elegant operations on matrix rows and columns] https://mathematica.stackexchange.com/questions/3069/elegant-operations-on-matrix-rows-and-columns

Question

The Mathematica tutorial has a section ’Basic Matrix Operations’, describing operations like transpose, inverse and determinant. These operations all work on entire matrices. I am missing a ...

- asked by sjdh (147 votes), answered by Mr.Wizard (50 votes)

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

[Number Formatting Functions Do Not Evaluate with ExportString] https://mathematica.stackexchange.com/questions/158694/number-formatting-functions-do-not-evaluate-with-exportstring

I need to export in a particular text file format and tried NumberForm, PaddedForm, AccountingForm, and DecimalForm to see which would work best. To my surprise only NumberForm evaluates when ...

- asked by Edmund (3 votes)

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[DSolve Throw::nocatch: Uncaught Throw[$Failed,balancefail] returned to top level. error in 11.2] https://mathematica.stackexchange.com/questions/158817/dsolve-thrownocatch-uncaught-throwfailed-balancefail-returned-to-top-level

Reported also to WRI. [CASE:3965533]

I am in the process of updating Kamke differentional equations tests for 11.2 when encountered a new error I have not seen before on one of the Kamke ODE’s ...

- asked by Nasser (3 votes)

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[Solve for several constants using a set of initial conditions] https://mathematica.stackexchange.com/questions/158783/solve-for-several-constants-using-a-set-of-initial-conditions

I have a set of differential equations that I am trying to solve for chemical reaction rate constants. So far I can get DSolve to solve the ODEs with initial conditions which provides the chemical ...

- asked by razzle_dazzle_84 (1 vote)