[R] fft help

M.Kondrin mkondrin at hppi.troitsk.ru
Wed Mar 12 01:55:54 CET 2003

Kenneth Cabrera wrote:

> Hi R-users:
> I want to know if there is an easy way to obtain a Fourier Transform form
> a vector or an array (just like fft does),  but with a more density base.
> I mean, if I have a vector of 512 of length, I want the Fourier 
> Transform to
> be 1024, or 2048, etc, in length (de u domain). Or should I modify the
> fft C code to do that?
There is no point in it. Procedure you are proposed to do is just sort 
of smoothing - it adds no new information. You see - fourier transform 
is just definition of new coordinates in functional space. If you have 
512 points - this is dimension of this space and coordinate basis can 
have only 512 vectors. Any other vectors (additional points in fourier 
transform) are linear combinations of them.

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