/sci/ - Science & Math » Thread #12850754

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FFT

Anonymous Thu 18 Mar 18:14:59 2021 No.12850754 View Reply Original Report

Quoted By: >>12850810 >>12850811

Is there an algorithm analogous to FFT but in curvilinear coordinates? Like an FFT for spherical harmonics for instance?

Anonymous

Anonymous Thu 18 Mar 2021 18:16:15 No.12850758 Report

Quoted By: >>12850767 >>12850825

Legendre transform.

Anonymous

Anonymous Thu 18 Mar 2021 18:17:55 No.12850767 Report

Quoted By:

>>12850758
Hm, didn't think of that. Are there efficient Legendre transform algorithms out there? What's their O complexity? Does it depend on the function being transformed?

Anonymous

Anonymous Thu 18 Mar 2021 18:26:48 No.12850810 Report

Quoted By:

>>12850754
Yes here is the polar fourier transform itself
https://www.researchgate.net/publication/241069465_Two-Dimensional_Fourier_Transforms_in_Polar_Coordinates
And here is a polar FFT algorithm
https://elad.cs.technion.ac.il/wp-content/uploads/2018/02/30_PolarFFT_ACHA.pdf

Anonymous

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Anonymous Thu 18 Mar 2021 18:26:51 No.12850811 Report

Quoted By:

>>12850754
wtyf is that./ im drunk but that integral is fisting my ass. wats 1 over 2 pi, and F of x time e (i assume Eulers number) but to the power of MINUS complex x so a clockwise rotation into the cmplex plane times t DX ???? wtf man, calculus was a LONMG time ago for me

Anonymous

Anonymous Thu 18 Mar 2021 18:30:12 No.12850825 Report

Quoted By:

>>12850758
This is much more natural than fourier, yes use legendre transform for spherical harmonics

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