CODEWITHSUNDEEP
c#matlabfftfftw
apocalypse
apocalypse

Reputation: 5884

FFTW wrapper and Matlab

FFTW wrapper: 

plan = fftwf.dft_1d (n, pin, pout, fftw_direction.Backward, fftw_flags.Estimate);

Matlab:

g = fft (samples, 2048)

Now I get almost correct results, but the Im values from FFTW wrapper have different sign. If i read values from then end of g to beggining - values will be ok.
Why FFT from Matlab is different than FFT from FFTW? Is any parameter to tell FFTW to order data?

Upvotes: 0

Views: 579

Answers (1)

Paul R
Paul R

Reputation: 213170

You have the direction as backward in the first case, so it's an inverse FFT. Change it to forward:

plan = fftwf.dft_1d (n, pin, pout, fftw_direction.Forward, fftw_flags.Estimate);

Upvotes: 2

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