Index mappings for the fast Fourier transform
James C. Schatzman · IEEE Transactions on Signal Processing · 1996
General analysis shows which linear index maps for the multidimensional PFA avoid twiddle factors. For any input map of this class, there is a unique output map which omits twiddle factors and modifications of the underlying DFT subblocks. With subblock modifications, all factorizations can be done in-place and in-order.