The total number of complex additions required to compute N point DFT by radix-2 FFT is:
A. (N/2)log2N
B. Nlog2N
C. (N/2)logN
D. None of the mentioned
Answer:A
The total number of complex additions required to compute N point DFT by radix-2 FFT is:
A. (N/2)log2N B. Nlog2N C. (N/2)logN D. None of the mentioned
Explanation: The decimation of the data sequence should be repeated again and again until the resulting sequences are reduced to one point sequences. For N=2v, this decimation can be performed v=log2N times. Thus the total number of complex additions is reduced to Nlog2N.