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Reputation
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 Sep13 revised How can I prove this trigonometric equality? the *proper* fix... Sep13 comment Proof: Series converges $\implies$ the limit of the sequence is zero Lona: Robin fixed them, see the edit history to see what was there. Sep13 comment sangaku - a geometrical puzzle This one's the most elegant of the lot, IMHO. :) Sep12 comment What is a conditional double limit and how to compute it? What's $k$ supposed to be? Sep12 comment The intuition behind generalized eigenvectors Arturo: Oh okay, I got confused because I work with eigenvalues/eigenvectors of matrix pencils (which is also called the generalized eigenproblem in numerical linear algebra books). Sep12 comment The intuition behind generalized eigenvectors If you don't mind clarifying, you're referring to the generalized eigenproblem $\mathbf{A}\mathbf{x}=\lambda\mathbf{B}\mathbf{x}$, yes? Sep12 comment sangaku - a geometrical puzzle i.e. a 30-60-90 triangle, but it isn't that obvious until you actually go through the derivation. :) Sep12 revised sangaku - a geometrical puzzle added 38 characters in body; deleted 25 characters in body Sep12 answered sangaku - a geometrical puzzle Sep12 comment Computing the largest Eigenvalue of a very large sparse matrix? @Gadi: Unfortunately, Arnoldi does require an array to represent the vector. Is $\mathbf{v}$ sparse or dense? I'm thinking maybe conformal partitioning might be of use here. Sep12 comment How do I map a spherical triangle to a plane triangle? As mentioned in ingentaconnect.com/content/acsm/cagis/1992/00000019/00000002/… , there are pitfalls in implementing Chamberlin properly; that may be what tripped you up. Sep12 comment How do I map a spherical triangle to a plane triangle? There also seems to be the modification by Buckminister Fuller of the Chamberlin projection: ingentaconnect.com/content/acsm/cagis/1994/00000021/00000004/… . In any event, could you try showing us how you implemented the Chamberlin projection, and maybe we can debug from there? Sep12 revised Terminology for point in dent in surface? retag Sep12 comment Terminology for point in dent in surface? The only term I could find is "elliptical" point (the signs of $\kappa_1$ and $\kappa_2$ are the same), so maybe you can just invent a new adjective to add to "elliptical". Sep11 comment Fourier Analysis textbook recommendation "I am not terribly interested in applications" - Dang, and I was about to recommend Brown and Churchill too. Sep10 revised Tiling Posters on a Wall tags Sep10 comment Why is median age a better statistic than mean age? To use more terminology: the median is a "robust" estimator of "central tendency": the mean is easily thrown off by even a few outliers. But yes, for badly behaved distributions, merely reporting central tendency alone is not enough. In any event: remember that there are countries with more tots than seniors, and then there are countries where most of the people are over the hill (due to e.g. sociological pressures for not having kids). Sep10 comment Prerequisites for learning (basic) Graph Theory Niel, thanks for this; my familiarity with graph theory is due to my knowledge that depictions of molecules in chemistry can be encoded as appropriate adjacency matrices, but I have yet to figure out how to apply what I already know in linear algebra to graph theory. I really should get off my lazy bum and devote some time to studying graph theory thoroughly. Sep10 comment Is this interpretation of Stieltjes integration correct? It can't be volume, $f(x)$ and $\mathrm{d}g(x)$ are supposed to have the same dimensions of "length" and area units are the square of length units. Sep10 revised Computing the largest Eigenvalue of a very large sparse matrix? edited tags