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 Aug 29 comment Integral of x^p Well, $\lim_{p\rightarrow -1} \frac{x^{p+1}}{p+1}=\ln(x)$. Not that mathematica knows this, though (try Limit[x^(1 + p)/(1 + p), p -> -1]) Aug 27 comment Numerical error in Mathieu functions Mathematica doesn't like Mathieu functions Aug 23 comment ToExpression from commandline I think it is a bug, in the sense that eg Plot[Sin[x],{x,-5,5}] doesn't cause mma to hang. So, while I agree that the fact that it fails is not a bug, that it hangs seems to be. Or am I missing something? Aug 22 comment Importing multiple images for machine learning classification something like Import[#] & /@ FileNames["folder/*.jpg"] is what you want. Mathematica has about 3 gigabytes of documentation. Aug 15 comment Finding average error of the data @Mike a) that code doesn't work unless I know temp, b) is it too much to ask what doesn't work with LinearModelFit or the NonlinearModelFit example I gave? Aug 15 comment Finding average error of the data If, for example, dat = Table[{x, Sin[x] + RandomReal[{-.2, .2}]}, {x, 0, 10, .1}]; (because the code you gave needs a location and other parameters and I don't know, nor want to learn, how to set that) then eg mdl = NonlinearModelFit[dat, a*Sin[b*x] + c, {a, b, c}, x] finds a model and you can find for example the variance like so Variance[dat[[All, 2]] - mdl /@ dat[[All, 1]]]. Aug 15 comment Efficient Langevin Equation Solver @chris I don't know to be honest. Why not write to him? Aug 14 comment Test a wooden board's vibration mode @Mr.Wizard OK, as you can see I did not vote for it to be closed. Maybe you're right. Aug 14 comment Test a wooden board's vibration mode @Mr.Wizard Also, it's not that unreasonable to expect that the answer to this could be modified to apply here. Does it? Does it not? Why not? We're not told. Aug 14 comment Test a wooden board's vibration mode @Mr.Wizard I'm not implying that anybody is getting pressured. All I am saying is that this is a question of precisely the same type as the one I posed, which presumably you'd not find good (as it is not well written, not necessarily valuable for future readers unless and not of reasonable scope, as it does not even attempt to express things in programming terms). That is, it does not satisfy 3 of the 4 criteria in the question you linked to. Aug 14 comment Test a wooden board's vibration mode @Mr.Wizard Would you also think that "please show me how to find the ground state of the 2d Kitaev model with Mathematica's linear algebra tools" is of reasonable scope? If not, why not? (in fact, mine is a much, much less technically involved question--unless we do include the spruce bit). Aug 8 comment unlisting a nested list do you mean that you literally have the symbol c and would like to end up with c1 and c2? Aug 8 comment Removing some data and replacing them with new ones In addition to what @RunnyKine said, here's what actually happened: you ask a question that seems to be answered by Differences. Then it turns out what you actually want is a filter to replace data if (roughly) the gradient is higher than some value by some interpolated value. But this is only clear from reading the comments. It would help in getting an answer if you included the info from the comments in the question (maybe with a short version of your data and some rough attempt to do what you want). Basically, imagine you don't know what the question is. Aug 7 comment $SU(4)$ Structure constants in mathematica So where did you get stuck? Aug 7 answered How to sort my list? Aug 7 answered How to integrate a function which is only known at discrete points Aug 5 comment Matrix containing ellipse Doesn't MorphologicalComponents[ Rasterize[Graphics[Disk[{0, 0}, {2, 1}]], ImageSize -> 800]] give a matrix? Aug 4 comment How to make Eigensystem in version 10 produce the same results as version 9 @xslittlegrass right, I know the closed form solution from the papers I cited (that's where I first saw them, but I am not sure if they first appeared elsewhere). If you're interested in general potentials and/or time dependent solutions then you indeed have to do it this way (numerically). As to how I knew it, I guess it's like asking "wow how did you know this is the Schrodinger equation?" isn't it? Now, if you had an interacting Hamiltonian and I spotted the potential, that would have indeed been noteworthy :) Aug 4 comment How to make Eigensystem in version 10 produce the same results as version 9 Actually, your Hamiltonian is literally that of a SHO on a 1d lattice (plus noise). You can find analytical solutions to this here or here, although I'm not sure how useful they are to you. Aug 4 comment How to make Eigensystem in version 10 produce the same results as version 9 @Jens I think here it really is due to degeneracies. It would have been useful to have a canonical question and answer to this somewhere.