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Re: FFT OF A NON RECTANGULAR IMAGE [message #63160 is a reply to message #63086]

Tue, 28 October 2008 18:35

R.G. Stockwell
Messages: 363
Registered: July 1999

Senior Member

<pgrigis@gmail.com> wrote in message
news:a67d1bc7-604e-4d94-83c3-e2ff5d662a1c@p10g2000prf.google groups.com...
>
>
> R.G. Stockwell wrote:
>> <pgrigis@gmail.com> wrote in message
>> news:3cb784b7-dfed-4c87-a2ab-d775d1edec0e@f40g2000pri.google groups.com...
>>> Maybe you could do a (slow) FT instead of FFT?
>>>
>>> Ciao,
>>>
>>> Paolo
>>
>>
>> Not directly. DFT and FFT are the same, the difference is in how the
>> calculation is done.
>
> What I meant was, for every frequency vector (kx,ky),
> evaluate the Furier transform F(kx,ky) by computing
> the integral of the input function (or table of values)
> multiplied by the Fourier basis function of kx,ky over
> the elliptical domain....
> On second thought, this would be extremly slow...
>
> Ciao,
> Paolo

I stake my life (no wait, your life) on the fact that the final result would
be
identical, allowing for differences due to lost precision (FFT would be
superior in that respect).

Cheers,
bob

PS try it out, you can write a DFT in about 3 lines.

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[Message index]

		FFT OF A NON RECTANGULAR IMAGE By: legall_alice on Tue, 28 October 2008 09:23
		Re: FFT OF A NON RECTANGULAR IMAGE By: legall_alice on Tue, 28 October 2008 20:56
		Re: FFT OF A NON RECTANGULAR IMAGE By: R.G. Stockwell on Tue, 28 October 2008 18:35
		Re: FFT OF A NON RECTANGULAR IMAGE By: pgrigis on Thu, 30 October 2008 08:10
		Re: FFT OF A NON RECTANGULAR IMAGE By: Kenneth P. Bowman on Tue, 28 October 2008 11:12

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