Szabolcs

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	35,145 reputation	bio	website		visits	member for	1 year, 5 months
483216 badges		location	ND		seen	18 hours ago

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Jun 4	revised	Determining which rule NIntegrate selects automatically added 105 characters in body
Jun 4	answered	How to get (fg)' = f'g + g'f?
Jun 4	awarded	Nice Question
Jun 1	comment	Does `Eigenvalues` evaluate in a parallelized way? @matheorem Because Eigenvalues doesn't use Mathematica's parallelization. `Parallelize` can only deal with high level Mathematica constructs while Eigenvalues is implemented in a low level language for dense numerical matrices. Mathematica is just calling this low level multithreaeded implementation.
May 31	comment	How can I get precisely the subgraph corresponding to a set of edges? Isn't your expected output exactly the same as your input, i.e. `Graph[Most[e]]`? What exactly are you trying to do?
May 31	comment	Creating a Mathematica executable that uses JLink I don't believe this is possible with FreeCDF, others will tell you if it's possible using Enterprise CDF ...
May 30	comment	Having used Mathematica as a “gateway” language, where to from here? @OleksandrR. I was looking at Pure the other day. As far as I know, it's the only general purpose language based on term rewriting that has a potential of being useful. (It's predecessor, Q, is not developed any more.) It even has some math libraries (a GSL interface).
May 30	comment	Difference In Eigenvectors @James What I showed here is not how to compute eigenvalues, but how to compare the output across systems... Mathematica's result is very likely to be correct because it agrees with MATLAB's.
May 30	comment	Difference In Eigenvectors This is the full output of Eigensystem with Mma 9.0.1 64 bit on OS X: pastebin.com/VqKN88sG
May 30	answered	Difference In Eigenvectors
May 30	comment	Difference In Eigenvectors And I found the mistake ... they are actually the same with MATLAB. I took the wrong transposition of the eigenvector output from MATLAB. In Mathematica, every row is an eigenvector. In MATLAB, every column is an eigenvector. Did you by any chance make the same mistake?
May 30	comment	Difference In Eigenvectors I just compared the eigenvectors between MATLAB and Mathematica for this matrix and they aren't the same either. It doesn't look right. I'll play with it a bit more to see if I've made any mistakes and I'll get back to you later.
May 30	revised	Difference In Eigenvectors added 454 characters in body
May 30	comment	Difference In Eigenvectors "Should not be" does not sound very confident. Why can't you just check if there are any instead of guessing that there aren't?
May 30	comment	How do I sort complex numbers? Please try to put yourself in an answerer's shoes. Both this one and your latest question simply can't be answered without more information. Think about this before you post and make sure your questions are clear. "but that does not sort the complex numbers as I want them to" <-- how should we know how you want them to be sorted? There's no standard way to sort complex numbers. If you re-read your question, it should be obvious what's wrong with it.
May 30	comment	Difference In Eigenvectors Do you have degenerate eigenvalues? Then the eigenvectors would not be unique. In any case, it's not possible to answer this without seeing at least an example matrix and the MathCad output. Are you suspecting one of the systems is returning a wrong result? Did you verify that the eigenvectors are correct by substituting them back?
May 29	awarded	Enlightened
May 29	awarded	Nice Answer
May 29	comment	Finding all simple paths between two vertices in a graph Note that for a mathematician, "enumerate" means "count".
May 29	comment	why ParallelDo do not do right? ... but that will effectively destroy parallelization here. Mathematica doesn't actually use threads but separate processes that can't access the same memory, so `SetSharedVariable` forces that variable to be accessed through the main kernel only. Your code would not run in parallel. Generally, I'd say that in this particular case if your program can't be reformulated to avoid constantly using a mutable variable then don't do it in Mathematica. If you want to make it fast, write it in C++. You seem to be coding in a low-level style anyway.