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All code in my contributions on Mathematica.SE, unless otherwise specified, is dual-licensed under CC-by-SA 3.0 and your choice of any one of the following:


9h
awarded  Yearling
2d
comment How to Compute 2D Convolution
ListConvolve!
2d
comment Experiment design in statistics
No matter where you post this question, it is unlikely that you will get a good response if you include only a copy of the assignment as you did here. Nobody on StackExchange is going to do your homework for fun, so showing your own progress (or highlighting where you are having problems) is critical to getting a good answer.
Jan
26
comment Largest matrix size supported by Mathematica 10
The other thing is, many matrix operations have a complexity of between $O(N^2)$ and $O(N^3)$. So, be prepared for your calculation with the $2^{20}$ matrix to take several (tens of) thousands of times longer than "quite a while".
Jan
26
comment Largest matrix size supported by Mathematica 10
@rcollyer 32GB DIMMs also tend to be substantially more expensive per GB than 16GB. That's why I suggested 256GB per computer rather than 512GB.
Jan
26
comment Largest matrix size supported by Mathematica 10
@rcollyer the cheapest way is probably to get 32 computers each with 256GB of RAM, connect them together using 40Gbit/s Infiniband, and install vSMP on them. Alternatively you could buy an SGI UV.
Jan
26
comment Largest matrix size supported by Mathematica 10
A $2^{15}$ dense square matrix takes 8GB of RAM. A $2^{20}$ one takes 8TB. Do you have that much RAM? I think Mathematica should be able to handle it, if your OS can. However, I've never tested this, as the biggest computer I have access to has only 4TB of RAM, and Mathematica isn't available on it.
Jan
26
comment What is a Horn Clause?
Or cs.stackexchange.com
Jan
26
reviewed No Action Needed Maintain a function quality of an expression
Jan
26
reviewed Approve I need some GPU benchmark for Mathematica
Jan
26
reviewed Approve Updating a GUI with ComboBox using GUIKit
Jan
26
comment Mathematica GUIKit
The GUIKit was obsolete a very long time ago (on the introduction of Mathematica 6) and suffered from many bugs. A not-too-dissimilar alternative is David Bailey's Super Widget Package, but it too is somewhat out-of-date, with the last update in November 2011. The implementation of the front end would tend to suggest that the Dynamic interface features are the ones to use now.
Jan
26
comment Permanently rounding numbers/values to a given number of significant figures
@George not really relevant to the question, but IMO it would be more helpful for the students if they were told that, if they aren't prepared to do the error analysis at least semi-rigorously (i.e., not using the wildly inaccurate "significant figures" method), then they had better not round intermediate results, and must keep plenty of guard digits throughout the calculation. This would make your life easier by allowing you to mark any incorrect answer as incorrect, rather than having to guess what results could potentially have been produced by premature rounding. What do you think?
Jan
25
revised Delayed evaluation of assignment
added 46 characters in body
Jan
25
comment Maximize[Cos[x - 1], x] is not evaluated
It does seem strange that Maximize checks that the period is nonnegative, unless it is actually expecting to receive negative periods for some reason. Nor is this a new phenomenon; the same results are observed all the way back to (at least) version 5.2. But without knowing their reasons for doing it this way, it's hard to assess whether this is a bug or not. Anyway, +1 for a good diagnosis.
Jan
25
comment Fit convoluted Gaussian and Lorentzian functions to a peak profile
No -1, but this is not correct; here you are just fitting arbitrary models whereas OP is clear that he has a model that is a convolution of a Voigt function and a top-hat function. I was going to answer this one myself at one point but I forgot, and then the other question came up that solved the same problem using NIntegrate. I think the solution in the other question is perfectly fine, so I VTC.
Jan
25
comment Is there any strategy to have a compiled version of FindFit or NonlinearModelFit?
@Shredderroy there are several examples of that nature (as well as fitting examples) in the body of the answer. The examples in the notebook are intended mainly as tests and not to be particularly explicative. In your case you would just type NelderMeadMinimize[x^2, x]. Please note that NelderMeadMinimize generates compiled code but by itself is not compilable--see the text of the answer for details of how to use its output in other compiled contexts. I suppose this is not of general interest to most people, but please feel free to ask about this in the chat.
Jan
25
answered Is there any strategy to have a compiled version of FindFit or NonlinearModelFit?
Jan
25
revised Display level of recursion of a recursive function during execution
edited title
Jan
25
comment Display level of recursion of a recursive function during execution
@OP could you please advise on whether or not the comments above have correctly understand the issue? If not then could you please expand on why Length@Stack[] is not what you are looking for?