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Re: spectral derivation of aperiodic function
Posted:
Feb 11, 2013 4:51 PM


On Tuesday, February 12, 2013 9:15:43 AM UTC+13, Eileen Tudaleft wrote: > bouloumag disgorged this amusing substitute for thought: > > > > > I would like to calculate the spatial derivative of a variable defined > > > on the points of a uniform grid. The domain is NOT periodic, so the FFT > > > method is useless here. > > > > really? > > > > Google: aperiodic FFT > > About 179,000 results (0.22 seconds) > > > > so all of that is entirely wrong? > > > > > I wonder if there exist other spectral methods > > > to calculate the derivative on an aperiodic domain or if my only hope is > > > to use the finite difference method? > > > > no, it's likely your 'other hope' is to spend some time thinking more carefully about your problem(s).
Yes, I was bemused by this post also. It implies that Kolmogorov's 5/3 law of turbulence and all other such work is rubbish. Perhaps OP is confusing nonperiodic with nonstationary? FFT is not good for nonstationary data.



