[help-gsl] Quick FFT question (2008-07-22)
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From: |
Nghia Ho <nghiaho12@.........> |
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Subject: |
Quick FFT question |
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Date: |
Tue, 22 Jul 2008 09:37:42 -0700 (PDT) |
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To: |
Help-gsl@gnu.org |
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Cc: |
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Hi,
I need to implement an algorithm that makes use of the FFT to do some basic signal processing. Basically, given an array of numbers I would like to extract the coefficients of the N lowest frequency components.
The GSL document says the results are laid out such that index from 0 to N/2 are the positive frequencies and the rest are negative. My mathematical knowledge of FFT is limited so please bare with me on the next question. I see the real values are the same for both positive/negative side, but imaginary values flip. So if I take the magnitude (|Re + Imz|) of the first N values of the positive side would that give me what I want?
Thanks,
Nghia
