6.14 Tuesday, September 29, 2015

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Top new questions this week: 
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[Fast calculation of discrete logarithms] http://mathematica.stackexchange.com/questions/95590/fast-calculation-of-discrete-logarithms

Does Mathematica have any built-in fast algorithms for calculating discrete logarithms over \((\mathbb {Z}_p)^\times \) (the group of integers modulo \(p\))?

Essentially, for a fixed large prime p, a ...

- asked by 2012rcampion (15 votes)

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[What pseudo-random number generators are available to Mathematica users?] http://mathematica.stackexchange.com/questions/95533/what-pseudo-random-number-generators-are-available-to-mathematica-users

One would think I should be able answer the question I pose in the title for myself by reading the Documentation Center article ref/SeedRandom, but it’s not so simple.

That article does give a list ...

- asked by m_goldberg (13 votes), answered by ilian (15 votes)

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[Efficient conversion between two partition representations] http://mathematica.stackexchange.com/questions/95410/efficient-conversion-between-two-partition-representations

I have a list of distinct expressions. We can represent a partitioning of list in two ways:

As a list of sublists partitions = a, b, ..., x, y, ..., ....

As a vector of integer partition ...

- asked by Szabolcs (12 votes), answered by Leonid Shifrin (12 votes)

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[Why do singularities disappear when performing convolutions with the Dirac Delta function?] (http://mathematica.stackexchange.com/questions/95588/why-do-singularities-disappear-when-performing-convolutions-with-the-dirac-delta)

I am attempting to perform a convolution involving the Dirac Delta function:

\(\int _{-\infty }^{\infty } \frac {1}{t+1} \cdot \delta (t+1)\ dt\)

I would expect that the result of this integral is ...

- asked by Peter Crowley (11 votes), answered by I_Mariusz (1 vote)

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[Determine height of box packed with spheres] (http://mathematica.stackexchange.com/questions/95566/determine-height-of-box-packed-with-spheres)

I got such a wonderful answer regarding The Diagonals of a Regular Octagon, so I thought I’d try asking another question we had on our Pizza and Problem quiz activity at College of the Redwoods. The ...

- asked by David (10 votes), answered by KennyColnago (10 votes)

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[How to automatically remove text from images?] (http://mathematica.stackexchange.com/questions/95512/how-to-automatically-remove-text-from-images)

I’d like to remove the text in the center of images automatically. To use Inpaint[], you need a mask, but I don’t have one. So really the problem is:

How to build a mask for an image that contains a ...

- asked by M.R. (10 votes), answered by blochwave (36 votes)

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[Front ends gone wild with named slots] (http://mathematica.stackexchange.com/questions/95351/front-ends-gone-wild-with-named-slots)

Bug introduced in version 10

Assume the following simple expression

{#"Test"}&

Now go in front of the # and just start typing another named slot expression. On my system, the front end ...

- asked by halirutan (10 votes)

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

[Python-style plots in Mathematica] http://mathematica.stackexchange.com/questions/84877/python-style-plots-in-mathematica

I love making plots in Mathematica. And I love to spend a lot of time making high-quality plots that maximize readability and aesthetics. For most cases, Mathematica can make very beautiful images, ...

- asked by Pablo Galindo Salgado (48 votes), answered by halirutan (49 votes)

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[How to find all the local minima/maxima in a range] http://mathematica.stackexchange.com/questions/5575/how-to-find-all-the-local-minima-maxima-in-a-range

I want to find :

all local maxima in range

all local minima in range

From those points I can interpolate and combine functions upper and lower boundary. What I am really interested in, is the ...

- asked by Margus (51 votes), answered by Daniel Lichtblau (55 votes)

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

[Time complexity to choose the right overload from the memoized function] http://mathematica.stackexchange.com/questions/95399/time-complexity-to-choose-the-right-overload-from-the-memoized-function

If we want to save some outputs of the function, we often use the memoization pattern as follows,

f[x_]:=f[x]=x 
f/@Range[10^5]

If I call this function many times for different arguments, ...

- asked by Sungmin (7 votes)

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[Diagonalisation of equations for NDSolve] http://mathematica.stackexchange.com/questions/95383/diagonalisation-of-equations-for-ndsolve

I have a linear matrix differential equation and I wish to speed up evaluation by diagonalising using eigenvectors. There is an example in Help for finite elements under "swinging beam" that is ...

- asked by Hugh (2 votes)

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[TableDirections example produces an error message] http://mathematica.stackexchange.com/questions/95321/tabledirections-example-produces-an-error-message

Bug introduced in 10.0 and persisting through in 10.2

Can anyone replicate this? In Mathematica 10.2 on Win 64:

TableForm[{{a, b}, {c, d}, {e, f}}, TableDirections -> Row]

I get the ...

- asked by Alan (9 votes)