[R] fft inverse display help
Dieter Menne
dieter.menne at menne-biomed.de
Thu Oct 2 08:48:48 CEST 2008
<rkevinburton <at> charter.net> writes:
>
> ff <- complex(length(fs))
> ff[9] <- fs[9]
> ff[5] <- fs[5]
>
> Include the DC component:
>
> ff[1] <- fs[1]
>
> Take the inverse
>
> fi <- fft(ff, inverse=TRUE) / length(ff)
>
> Plot
>
> plot(fi)
>
> Notice that the plot is the Re vs. Im on the x and y axis' respectively.
In one case, you plot a complex vector (gives points in complex plane), in the
other case a time series, where default assumption with a warning is to plot the
real part only.
Try
plot(as.ts(fi))
and you see the latter, where implicitely plot.ts is called.
Dieter
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