Extension of Winograd multiplicative algorithm to transform size N=p2q and its implementation

The authors continue a program of designing multiplicative FFT (fast Fourier transform) algorithms with highly structured data flow. They take up the case of transform size N, N=p²q, where p and q are distinct odd primes. Number-theoretical methods are used to decompose the indexing set into orbits based on its multiplicative ring structure of Z/N, N=p²q. A family of variants of the fundamental algorithm is designed, presenting options as to whether additions or multiplications dominate arithmetic cost