Geoff Oxberry
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 Oct2 comment Expand $f(x) = x$ in a cosines serie If you use $-l$ to $l$, then because $x$ is an odd function, cosine is an even function, and the product of even and odd functions is odd, the cosine terms in your Fourier series will drop out, leaving you with only sine terms. Sep25 comment Wave Equation with Constant Boundary Conditions Welcome to SciComp! This question is a problem that doesn't require techniques in computational science, and it's probably a better fit for Mathematics Stack Exchange. Feb24 comment The space spanned by the rows of the Kernel matrix. This question has been cross-posted on Computational Science Stack Exchange. See scicomp.stackexchange.com/q/10860/276. Dec4 comment Transform derivative term of 2nd order Yes, this question probably should be migrated to Math.SE (if they want it). Apr18 comment How many significant figures are needed in base 2? @Must: I don't know yet. Let me consult with the math mods. Apr18 comment How many significant figures are needed in base 2? Question is very close to a cross-post on scicomp.SE. Apr4 comment Contiguous prime numbers with MPI (Want more ideas for an efficient algorithm) Math.SE mods: Cross post on scicomp.SE. Apr1 comment Contiguous prime numbers with MPI (Want more ideas for an efficient algorithm) scicomp.SE would also gladly take your question; we take lots of questions on MPI, and on the practical implementation of parallel algorithms. (I'm a mod on scicomp.SE.) Feb10 comment Rapid approximation of $\tanh(x)$ I thought about that algorithm, too, until I saw the "no table lookup" part. Feb9 comment Matrix-Square Root I thought about the polar decomposition method, too, when I looked at the problem, but then I thought about calculating it, looked it up, and came to a similar conclusion as J.M.. Feb8 comment Applied ODEs in trajectory problem Just to clarify, does $v$ have constant magnitude in the problem statement, or does $u + v$ have constant magnitude? If $u + v$ has constant magnitude, then I would expect both the magnitude and direction of $v$ to vary with the position of the boat, because $u$ is a constant vector. Feb6 comment Find roots of sum of sinusoids Just out of curiosity: if this equation describes the motion of a point and a line, is there any way that you could set it up differently, as a system of ODEs, where the collision event is described by the root of an equation? There are event detection algorithms for numerical integrators that work well in such circumstances.