# episanty

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bio website location London, United Kingdom age 26 member for 2 years, 2 months seen 3 hours ago profile views 87

BSc in Physics at the National Autonomous University of Mexico (UNAM). Currently doing an MRes+PhD at the Centre for Doctoral Training in Controlled Quantum Dynamics at Imperial College London.

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 Jul1 revised Fourier series is to Fourier transform what Laurent series is to …? added 588 characters in body May8 awarded Yearling Apr11 comment Approximating dirac delta function with sinc functions This feels a bit circular. Isn't the integral in question the key element of the double-Fourier-transform theorem you invoke at the end? Apr10 comment Approximating dirac delta function with sinc functions Oh, yes, you are right - that's pretty subtle. You are again correct, it is cancellations and not absolute convergence that makes $K$ vanish, so it is essentially a version of the Riemann-Lebesgue lemma. I will redo that section when I have time. Apr10 comment Approximating dirac delta function with sinc functions Sorry, I didn't see that modification. You are right that the first term was incorrect. Your third term is not. Apr10 comment Approximating dirac delta function with sinc functions Yes, that is correct. Apologies. Apr10 revised Approximating dirac delta function with sinc functions deleted 10 characters in body Apr8 revised Approximating dirac delta function with sinc functions Removed brackets from QED symbol. Apr8 answered Approximating dirac delta function with sinc functions Apr2 comment How can a piece of A4 paper be folded in exactly three equal parts? And of course this has the advantage of utterly befuddling the recipient. Mar19 comment Non-invertible operators You should really split this question up into two. The first question is not quite clear: are you asking "are there linear operators on some vector space whose matrix representation is singular?"? If so, you should make it that precise. Mar8 comment Do we need to formally teach the Greek Alphabet? Note also that $\sum$ doesn't "start with" an S, it is an S. Similarly for $\prod$. Mar3 answered Help proving exercise on sequences in Bartle's Elements Mar3 comment Help proving exercise on sequences in Bartle's Elements Re: your last question, for the sequence $x_n=2+1/n$ the ratio limit is exactly one. For the criterion to apply, you need it to be strictly smaller than that. Feb10 comment Define positions of a set of points given (only) the distances between them @Andrewb If you provide a clear description of how you get from your initial distances to the new ones, then it will be easier to see. Be aware, though, that even with small perturbations if you do not have some specific geometric constraints in general the minimal dimension will still be $n-1$, because the determinant of the relevant matrix is a continuous function, and its zeros have measure zero. Nevertheless, the $(n-1)$-volume will be very small, though. Feb10 comment Define positions of a set of points given (only) the distances between them Re: your edit, it's not exactly clear what you mean. If you mean you have a set of points $\{p_k\}$ and a smooth function $f$, and you want to move each point by a multiple of the gradient, i.e. $p_k\mapsto p_k+h\nabla f(p_k)$, then there you have your answer. It's not clear what you mean by "multiply each distance by the appropriate mean gradient", but it sounds awfully like equating a vector to a scalar. If you provide more specific details about what you mean then I'll address that. Feb10 answered Define positions of a set of points given (only) the distances between them Feb3 comment First variation of Area applied to minimal surfaces It would help if you supplied more details on what formula you're confused about and what context it appears in. Jan28 revised Why is it trivial that $\left(1+\frac{2\ln3}{3}\right)^{-3/2}\leq\frac{2}{3}$? Made title reflect the question. Jan28 suggested suggested edit on Why is it trivial that $\left(1+\frac{2\ln3}{3}\right)^{-3/2}\leq\frac{2}{3}$?