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seen Mar 26 at 14:33

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:


Mar
17
awarded  Nice Answer
Mar
8
reviewed Approve How do I disorder a list in Mathematica?
Mar
6
reviewed Close RecurrenceTable
Mar
6
comment Launching 49+ local kernels fails in 10.0.2
I have seen this same problem in the past when creating huge numbers of MathLink connections (and you don't necessarily need to use that many kernels to do this). I don't know what causes it, but MathLink does seem to have difficulties with scalability in this scenario. By the way, could you please delete your comment above and add this information to the question? The MathJax formatting in the comment makes it unreadable and it messes up the rendering of the page. I do agree with other people that unless someone at WRI comes along, the question is probably not answerable by us as users.
Mar
5
comment How can I import a pickled file?
Pickled items consist of serialized Python state. It is not necessary for this Python-specific content to have a meaning that exists independently of Python and that could be translated to other languages; an analogy could be asking how to read a .mx file in Python. I would suggest you read the file using Python and save the contents in a different format.
Mar
5
answered FindMinimum's WorkingPrecision behaviour
Mar
4
comment How to obtain the eigenvector corresponding to the minimal eigenvalue of a generailzed eigenvalue problem
I agree. You are using Mathematica, so pick the minimum programmatically using e.g. SortBy, Ordering, Position etc.
Mar
4
comment How to obtain the eigenvector corresponding to the minimal eigenvalue of a generailzed eigenvalue problem
Okay, then in that case perhaps you have to use Eigensystem without the second argument and retrieve all eigenvalues/vectors, and pick the one you want.
Mar
4
comment How to obtain the eigenvector corresponding to the minimal eigenvalue of a generailzed eigenvalue problem
You may use Eigensystem to get the eigenvalues together with their corresponding eigenvectors. For example, Eigensystem[N[{a, b}, 5], -1] for the smallest eigenvalue.
Mar
4
comment Is there a way to give Mathematica extra memory?
What you refer to could be adjusted by changing the symbolic cache settings (could; I do not know whether this actually has any effect on simplification). You can try it and see: SystemOptions["CacheOptions" -> "Symbolic"].
Mar
3
awarded  Revival
Mar
3
comment MKL on Intel vs AMD
For one thing, two AMD cores share one FPU. FPU is not needed very much in server applications, so they decided not to duplicate it for every core. It saves a lot of power and area, allowing more cores to fit onto one chip. But it does mean that for HPC applications, it takes two AMD cores to match one Intel core. This is not Intel's fault and it is not a deficiency of the AMD products. It merely reflects that they are designed and sold for different markets. Intel can include so much more cache than competitors because of their absolute process superiority, which they use to maximum effect.
Mar
3
comment MKL on Intel vs AMD
Alexey is talking about (effective) memory bandwidth, which will be hugely influenced by relative cache sizes and speeds. And even if MKL may not be optimal on AMD processors, it's still faster than ACML (AMD's own equivalent) and every other math library apart (perhaps, and even then very debatable) from ATLAS/OpenBLAS. So, sorry to disappoint you, but even allowing for Intel's favoring their own products, AMD CPUs are simply not as fast. They are not really sold for HPC applications anyway; the server market is more lucrative and this is what AMD aims at with their products.
Mar
3
answered Eigensystem on HPC
Mar
2
comment Linearization of differential equations at first order
In Mathematica, $\cos$ and $\sin$ are Cos and Sin. Note the capitalization. This is not an answer to your question, but you will not get a correct result without it. If you can simplify your question (and not use screenshots that people have to retype), you will be more likely to get an answer.
Mar
2
comment How can I cluster a continuous percentage?
You seem willing to spend more effort trying to imply some psychological defect on my part, than bringing your question up to community standards, or even solving your actual problem. I have to say, this bizarre response to even the mildest criticism speaks for itself.
Mar
2
comment Slow-down encountered when using NMinimize with a compiled function
It has some effect but the difference is not large. Compare e.g. Method -> {Automatic, RandomSeed -> 1}, WorkingPrecision -> MachinePrecision with Method -> {Automatic, RandomSeed -> 1}, WorkingPrecision -> 10, both for the compiled funciton. I think this is consistent with fewer iterations being performed more than anything else.
Mar
2
comment Slow-down encountered when using NMinimize with a compiled function
I am not sure. Your function looks fine. I don't have time at the moment to investigate further, I'm afraid.
Mar
2
comment How can I cluster a continuous percentage?
It is stated as a personal opinion that other people may agree or disagee with at their option. StackExchange sites are community-driven and based on a voting system for most decisions; judging by the votes, at least four other people agreed with me. Simply put, your question is not of the standard we are accustomed to receiving on this site, and if you want to have it re-opened, you should take care to clarify it. To turn your objection around, would you be willing to sign this poor effort with your real name, I wonder? Also, please note that it was not me who downvoted you.
Mar
2
comment Slow-down encountered when using NMinimize with a compiled function
NMinimize does not require (and cannot accept) gradients. All its methods are direct search algorithms; there is no more information required than a black box function. If the Nelder-Mead method would be sufficient for you, perhaps you might like to try a compiled implementation of that.