So I've been looking at this butterfly diagram to try to understand it better:
And I am trying to get a good understanding of the twiddle factors.
The definition is given as:
FFT Twiddle Factor: ${e^{i2{\pi}k/N}}$ and IFFT Twiddle Factor: ${e^{-i2{\pi}k/N}}$
So k is the index number of the iteration thus $k=0,1...N$ but its $N$ that I am unsure of.
From the image is the first stage N = 8 (since there are 8 butterflies) or is N = 2 since each butterfly only spans two elements? Or is N always 16 every pass?
My guess currently is:
Stage 0 : N = 8
Stage 1 : N = 4
Stage 2 : N = 2
Stage 3 : N = 1
Am i correct in this assumption? If not i hope some one clarifying my misunderstanding here.
Thanks