CODEWITHSUNDEEP
fft
user1459175
user1459175

Reputation: 313

Inverse radix4 FFT

I have a radix4 FFT that works in forward direction. How different is the inverse fft from froward? I think the only difference is twiddle factors. My code is a modified version of Source. Can some one enlighten me on this. Thanks.

My output

  1. 50 688
  2. -26 -6
  3. -10 -16
  4. 6.0 -26

Expected output

  1. 50 688
  2. 6 -26
  3. -10 -16
  4. -26 -6

Upvotes: 0

Views: 320

Answers (1)

steveha
steveha

Reputation: 76735

Google search "how to compute inverse FFT". Top result:

http://www.adamsiembida.com/node/23

The equation:

IFFT(X) = 1/N * conj(FFT(conj(X)))

conj() means "complex conjugate", which basically just means multiplying all the complex values by -1.

http://en.wikipedia.org/wiki/Complex_conjugate

Upvotes: 4

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