Table 2: Number of operations of the different solutions.

Solution Number of complex Number of complex
multiplications additions

3-FFT solution 1 638 400 3 145 728

5-FFT solution 1 294 336 2 457 600
(−21%)(−21.9%)

9-FFT solution 1 228 800 2 408 448
(−25%)(−23.4%)

15-FFT solution 1 036 288 2 187 264
(−36.8%)(−30.5%)

The percentage is the reduction compared to the 3-FFT solution.