[R] a question about fft ( fast fourier transform)

[lma5@ncsu.edu]

Dear listers

 In R, if I have a sequence x(t), t=1,...N, fft(x) is actually giving us
sum(x(t)exp(-i*omega*t)) at fourier frequency omega= 2*pi*i/N,
i=0,1,...(N-1).

The question is if I want to calculate sum(x(t)exp(-i*2*omega*t)), how can
I do it?
thanks a lot!


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liyun (Lauren) Ma
Dept of Statistics
North Carolina State University