This paper describes the \fractional Fourier transform", which admits computation by an algorithm that has complexity proportional to the fast Fourier transform algorithm. Whereas the discrete Fourier transform (DFT) is based on integral roots of unity e ;2 i=n , the fractional Fourier transform is based on fractional roots of unity e ;2 i , where is arbitrary. The fractional Fourier transform and the corresponding fast algorithm are useful for such applications as computing DFTs of sequences with prime lengths, computing DFTs of sparse sequences, analyzing sequences with non-integer periodicities, performing high-resolution trigonometric interpolation, detecting lines in noisy images and detecting signals with linearly drifting frequencies. In many cases, the resulting algorithms are faster by arbitrarily large factors than conventional techniques.
The literature describes two algorithms that generalize the FFT on the unit circle: the Chirp Transform Algorithm (CTA) 15 and the Fractional Fourier Transform (FRFT) REF 17 .
The fractional Fourier transform and applications
SIAM Review
Mathematics Computer Science