[R] FFT, frequs, magnitudes, phases

[Peter Dalgaard]

Wolfgang Waser <wolfgang.waser at rz.hu-berlin.de> writes:

> Hi,
> 
> I'm in dire need of a fast fourier transformation for me stupid biologist, 
> i.e. I have a heartbeat signal and would like to decompose it into pure sin 
> waves, getting three vectors, one containing the frequencies of the sin 
> waves, one the magnitudes and one the phases (that's what I get from my data 
> acquisition software's FFT function).
> I'd be very much obliged, if someone could point out which command would do 
> the job in R.

fft(), but notice that it gives the complex transform. You need to do
a little homework to get at the magnitude/phase values. (Basically,
you just have to take Mod() and Arg(), but there some conventions
about the frequencies and multipliers that one can get wrong).

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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