We define the notion of the Fourier transform for the rook monoid (also called the symmetric inverse semigroup) and provide two efficient divideand-conquer algorithms (fast Fourier transforms, or FFTs) for computing it. This paper marks the first extension of group FFTs to non-group semigroups.

In this paper, we proposed an variable length FFT processor architecture which could be used in multi-mode and multi-standard OFDM communication system. Based on radix-2 single-path delay feedback architecture, FFT is implemented with the aid of LUT and control logic. The expected architecture would complete FFT ranging 2048/1024/512point. Keywords-FFT; Radix-2 FFT; variable length FFT;

The chirplet transform is the generalization form of fast Fourier Transform, short-time Fourier transform, and wavelet transform. It has the most flexible time frequency window and successfully used in practices. However, the chirplet transform has not inherent inverse transform, and can not overcome the signal reconstructing problem. In this paper, we proposed the improved chirplet transform (...

We propose an algorithm that uses the discrete wavelet transform (DWT) as a tool to compute the discrete Fourier transform (DFT). The Cooley-Tukey FFT is shown to be a special case of the proposed algorithm when the wavelets in use are trivial. If no intermediate coeecients are dropped and no approximations are made, the proposed algorithm computes the exact result, and its computational comple...