How many complex additions are performed in computing the N-point DFT of a sequence using divide-and-conquer method if N=LM?
A. N(L+M+2)
B. N(L+M-2)
C. N(L+M-1)
D. N(L+M+1)
Answer:A
How many complex additions are performed in computing the N-point DFT of a sequence using divide-and-conquer method if N=LM?
A. N(L+M+2) B. N(L+M-2) C. N(L+M-1) D. N(L+M+1)
Explanation: The expression for N point DFT is given as The first step involves L DFTs, each of M points. Hence this step requires LM(M-1) complex additions, second step do not require any additions and finally third step requires ML(L-1) complex additions. So, Total number of complex additions= N(L+M-2).