10,981 reputation
24577
bio website
location
age
visits member for 2 years, 5 months
seen 1 hour ago

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:


23h
comment Numerical evaluation of ChebyshevT
Numerical instability. N without any precision specified works in machine precision with precision tracking switched off. For high-order polynomials, this is a bad idea. When a precision is specified, the working precision is adjusted so as to ensure that all of the requested digits are correct.
1d
comment on convergence in optimization
Your judgment is required to say whether it is reliable or not. FindMinimum provides you with three different measures of the degree of convergence. From what you know about the problem, and the use to which you intend to put the result, is it good enough, or not? Nobody else can tell you this. If you want more concrete advice from others, I'm afraid you'll have to ask a more concrete question.
1d
revised on convergence in optimization
edited tags
1d
comment on convergence in optimization
"Can we still use this solution for when I calculate one of the constraints using printed data, it is outside the defined range?" does not really make sense to me. Could you clarify? Also, why have you used the linearprogramming tag for a nonlinear optimization problem?
2d
reviewed No Action Needed Plot the plane so different condition has a different color
2d
comment Game of Life in 3D
Your question has been closed once because the way you've phrased it is not particularly appropriate for the site; StackExchange sites are not discussion forums, so questions are expected to be more specific and directed. I voted to re-open since clearly it is possible to give a good answer to the question, but we would all appreciate it if you could revise your post into something more suitable for a question-and-answer format. The principal difficulty is that people are expected to vote on the answers, and unless specific criteria are given, it is hard to know how to do so.
2d
reviewed Leave Open What is the order of faces on a D20? How can I optimize the order of faces on a D-n?
2d
reviewed Leave Open How to limit only two “0 and 1” strings for an xor implement?
2d
comment Anti-aliasing not working in Mathematica 10 and Linux
Perhaps they linked against a different library version in the final build that introduced this problem. But this is sheer guesswork. If the problem persists despite the update I suppose you'll have to report it as a bug.
2d
comment Anti-aliasing not working in Mathematica 10 and Linux
Given the flashing problem you also reported: which graphics card driver version are you using, and is it the latest?
2d
revised What information is sent to Wolfram Research when loading or working with Mathematica?
adding some more situations where data is sent to the WRI servers
Jul
18
comment Minimization by Nelder-Mead
Glad to hear you're making progress! I'm sorry, but I really don't think I can help with this problem. My code never produces any inf or nan values, and nor does it perform any linear algebra. So, these values and the error are being produced entirely by your own code, which I haven't seen (and this isn't the place for it anyway). At a guess I would say that, because differential evolution evaluates the objective function with random parameters, perhaps for certain values of these parameters your function is not well behaved. If so, you need to check for that before evaluating it.
Jul
17
comment MinGW-64 and CompilationTarget -> “C”: can't make library
-O3 in gcc is supposed to maintain standards compliance, unlike in e.g. Intel C. -Ofast would be the potentially dangerous option. N.B. -O3 does not always produce faster code than -O2 and can actually be slower due to producing more, or more nonlocal memory accesses, or expanding the working set.
Jul
17
comment Strange behavior of MemberQ, Position
@Mr.Wizard duplicate of (15907), but the explanation given in that one is not as complete as here because it references a post on SO for the rationale rather than reiterating it. Could I suggest that they be merged, possibly including the SO answer (or a copy of it)?
Jul
17
comment Strange behavior of MemberQ, Position
The reason is really no mystery; not all numbers with a finite number of digits in base 10 can be also expressed with a finite number of digits in base 2. If not, then you get a truncated binary fraction, which comes out as a decimal number very close, but not exactly equal, to the desired value.
Jul
16
comment Version 10 of Mathematica in Windows XP
@m0nhawk the installer refuses to install on anything older than Vista (including Server 2003 R2 x64, which is only a few months older than Vista and currently in extended support for another year). I didn't try to override that to see what happens.
Jul
15
comment Problems extending NelderMeadMinimize into 2D
Just so you know, I have written some code for you which is almost working, but I'm having some trouble with type inference (a perennial problem with the Mathematica compiler). As soon as I've debugged it, I'll post the result.
Jul
15
comment What information is sent to Wolfram Research when loading or working with Mathematica?
I think this question is a better fit for the Wolfram Community, simply because it's an official Wolfram site, while this is not. As users we can't really say what they do with the data they gather. As far as I know, though, disabling Internet access does actually prevent the transmission of any information. I haven't checked the situation in version 10, so things could have changed recently.
Jul
15
comment Findfit doesn't give the good fit; Changing the starting values will not change the results
+1. N.B. you can obtain these results directly using e.g. ComplexFit[data, b + a/(c + s), {a, b, c}, s] from the notebook in the github or this answer.
Jul
15
comment Fitting fractional complex data with NonlinearModelfit
@AlexeyPopkov yes, that's possible at present (although these two sublists would simply be joined into one) but one cannot guess the weights automatically, so I simply didn't do anything with them. There is nothing stopping someone from using the Weights and VarianceEstimatorFunction options with ComplexFit provided they know how the transformation is done. For this you can specify "Hold" -> True and the transformed FindFit/NonlinearModelFit call is returned held rather than being evaluated.