7.1 Tuesday, December 30, 2014

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Top new questions this week: 
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[How would I return a random Mathematicacommand?] http://mathematica.stackexchange.com/questions/69627/how-would-i-return-a-random-mathematica-command

I’m doing some metaprogramming. How would I make a Mathematica function that returns a random Mathematica command? Is there a list of command names that I could use RandomChoice on?

I’m looking for ...

- asked by Alexander Gruber (10 votes), answered by bill s (16 votes)

—————————- [Rendering thousands ofpoints] http://mathematica.stackexchange.com/questions/69774/rendering-thousands-of-points

I am trying to render an image with some 120,000 Points. Technically it’s just 10,000 points, plus their reflection, plus 5 rotations of both of those sets, but I’m not sure that’s relevant. The code ...

- asked by Martin Buttner (9 votes), answered by Sjoerd C. de Vries (11 votes)

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[Truncating a list once all members of a set have appeared?] http://mathematica.stackexchange.com/questions/69613/truncating-a-list-once-all-members-of-a-set-have-appeared

Consider if you would the case where we have some list of elements:

list0 = 54, 4, 7, 9, 3, 54, 4, 20, 2, 456, 2, 3;

And we have some target list:

targetList = 2, 3, 4, 7;

We’d like to scan ...

- asked by GreenField (9 votes), answered by Mr.Wizard (4 votes)

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[Find the minimum integer r such that \((10^r - 1)/37\) is an integer] http://mathematica.stackexchange.com/questions/69811/find-the-minimum-integer-r-such-that-10r-1-37-is-an-integer

I know Element[(10^r - 1)/37, Integers] tests the condition.

So what is the command that gives me the minimum integer value r such that the condition is true?

- asked by LoveRight (7 votes), answered by Oleksandr R. (10 votes)

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[Definite integral incorrectly giving a nonreal value] http://mathematica.stackexchange.com/questions/69718/definite-integral-incorrectly-giving-a-nonreal-value

In Mathematica 10.0, when I enter

N[Integrate[Sqrt[1+x^3],{x,-1,3}]] 
 
, I get a nonreal value.  (I.e., the imaginary part is nonzero.)  Why? 
 
This arose when I was seeing if Sqrt[1_x^3] has an  ... 

- asked by Stephen Herschkorn (7 votes), answered by Nasser (6 votes)

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[LetterCharacter for Cyrillic symbols]http://mathematica.stackexchange.com/questions/69728/lettercharacter-for-cyrillic-symbols

Why does the code

StringMatchQ["bl", LetterCharacter]

return False?

Probably because:

StringMatchQ[bl", LetterCharacter] // HoldForm // FullForm 
...

- asked by molekyla777 (7 votes), answered by Karsten 7. (7 votes)

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[How discretize a region placing vertices on a specific non-uniform grid] http://mathematica.stackexchange.com/questions/69584/how-discretize-a-region-placing-vertices-on-a-specific-non-uniform-grid

Given a generic region, for example:

\[CapitalOmega] = ImplicitRegion[((2*x^2 + 3*y^2 + 2*x*y - 2 & )*lt; ) = (0^x^2 + y^2 & )*gt; 0.1, {x, y}]; 
 
and a non-uniform grid, for example: 
 
\[CapitalOmega]b = RegionBounds[\[CapitalOmega]]; 
{xg, yg} =  ...

- asked by unlikely (6 votes), answered by kguler (9 votes)

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

[Assign the results from a Solve to variable(s)] http://mathematica.stackexchange.com/questions/6669/assign-the-results-from-a-solve-to-variables

I understand Mathematica can’t assign the results of a Solve to the unknowns because there may be more than 1 solution. How can I assign the 4 values of following result to variables?

- asked by stevenvh (17 votes), answered by Artes (10 votes)

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[What are the most common pitfalls awaiting new users?] http://mathematica.stackexchange.com/questions/18393/what-are-the-most-common-pitfalls-awaiting-new-users

As you may already know, Mathematica is a wonderful piece of software. However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from ...

- asked by belisarius (184 votes), answered by Michael E2 (99 votes)

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

[DSolve versus DSolveValue] http://mathematica.stackexchange.com/questions/69793/dsolve-versus-dsolvevalue

I’ve just discovered the new command DSolveValue in Mathematica 10. Is this new command now the preferred instead of DSolve? Is it the better command to teach to students? Same question for ...

- asked by David (2 votes)

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[Font rendering difference between .jpg & .pdf] http://mathematica.stackexchange.com/questions/69825/font-rendering-difference-between-jpg-pdf

I have some planar graphics involving lines and text, produced by Line[] and Text[], accepting the default font on the latter. When I Save Graphics as .jpg, it looks fine, left below. When I save as ...

- asked by Joseph O’Rourke (2 votes)

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[Regular Polyhedra coordinate points generation] http://mathematica.stackexchange.com/questions/69839/regular-polyhedra-coordinate-points-generation

Is it possible to get all points on a Polyhedron surface using two surface parameters, say

\( \phi ,\theta \) spherical co-ordinates?

Just like in ParametricPlot3D, can we start with PolyhedronData ...

- asked by Narasimham (1 vote)