decimationinfrequency
Decimation in frequency, also known as decimation-in-frequency (DIF), is a method for computing the discrete Fourier transform (DFT) efficiently as part of the fast Fourier transform (FFT) family. It is one of the two canonical forms of the radix-2 Cooley–Tukey FFT, the other being decimation in time (DIT). In DIF, the decimation occurs in the frequency domain, and the computation proceeds by repeatedly splitting the DFT into smaller DFTs through butterfly operations that mix pairs of frequency components with appropriate twiddle factors.
Conceptually, DIF begins by partitioning the input spectrum into two halves. For each pair of frequency indices
DIF trades input-ordering and data flow to produce an efficient in-place computation, which can be advantageous