(1) The limit as a Gaussian's width (1/α) goes to zero is 0 (2) The same limit of the "Gaussian Sum" however is 1pic.twitter.com/3U7I4zsQ1r
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Couldn’t you use that theorem from complex analysis for transforming infinite sums of functions into contour integrals for the second one ?
Yeah, surprises me too! How did you come across this result?
just was wondering the discrete sum of a gaussian looks like, then realized it was close to root-π and then tried to see if they had similar limiting behaviors
thanks! :) i may need a couple days off in the future though haha
The fact that the Gaussian sum and integral are almost identical is an immediate consequence of the "modularity" of the Jacobi theta function (or, more generally, the Poisson resummation theorem). When α=1, the result is basically that π² is big.pic.twitter.com/IGLeYDc7rv
The difference is that measure can be concentrated at a point in the discrete case. It cannot in the continuous case. When you interchange the limit and integral, you get 0 everywhere except x=0 (or n=0).
Poisson summation on the second gives an almost closed form :)
A lot of these are great! Would you consider sharing your steps on a blog or something for some of these that are most interesting/important? Can just be phone shots of your hand-written notes ... or something simple.
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