[R] Stuck with FFT

[stephen sefick]

have you read in the data?  Have you made it a time series?  Did you call it z?

?fft
?spectrum

On Mon, Oct 27, 2008 at 2:01 PM, Rthoughts
<seb.brockel at northampton.ac.uk> wrote:
>
> Dear all,
>
> Before I can get into serious Fourier analysis of Radon time-series I am
> practising with 24hour and 24.8hour sinusoids to assist with my
> interpretation of signals ittributed to tidal input to Radon time series.
>
> I am stuck. I have tried researching this to no avail. I am awating a book
> that should describe fourier transforms in detail and another one that
> should discuss the R application.
>
> I know what the command line is but I can't get it to refer to the array.
>
> What is 'z'? If I have a table open entitled '24hsinusoids' with date/ time
> column by the hour from January 01 2008 00:00 to January 02 2011  00:00
> (X01.06.2008) (time column listed as X00:00) with corresponding sinudoidal
> signal value column (X100) to give a complete curve for 24hours spread as
> curves over the whole time-span, how can I fft from this table?
>
> fft(z, inverse = FALSE) gives me as; object 'z' not found.
>
> Please help and explain how R recognises the table and does fft's from it.
> The time-series is discrete and periodic (or should be, as I need to analyse
> my Radon time-series fro exactly this and I am very stuck now).
>
> Thank you with all my heart if you can help.
> --
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>
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>



-- 
Stephen Sefick
Research Scientist
Southeastern Natural Sciences Academy

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis