Table 3 Total number of arithmetic operations required to compute the input and output stages of DFT_{COMM−DIF−DIT−Pr} and DFT_{COMM−DIT−DIF−Pr} modalities

Direct method

6 (L _o  − 1) (L _i  − 1) + 2L _o (L _i  − 1)

((L _i  ≤ D _op )|(L _o  ≤ D _ip )) & (L _i  < 4)

2BF filtering method

(L _o  − 1) (2L _i  + 2) + 2 (L _i  − 1) + (L _o  − 1) (4L _i  − 2)

((L _i  ≤ D _op )|(L _o  ≤ D _ip )) & (L _i  ≥ 4)

Pruned decomposed transform

OPERtot of (8) using Table 2

(L _i  > D _op ) & (L _o  > D _ip )