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Many phenomena are described by bivariate signals or bidimensional vectors in applications ranging from radar to EEG, optics and oceanography. The time-frequency analysis of bivariate signals is usually carried out by analyzing two separate…

Methodology · Statistics 2016-09-09 Julien Flamant , Nicolas Le Bihan , Pierre Chainais

A major issue in harmonic analysis is to capture the phase dependence of frequency representations, which carries important signal properties. It seems that convolutional neural networks have found a way. Over time-series and images,…

Signal Processing · Electrical Eng. & Systems 2019-07-02 Stéphane Mallat , Sixin Zhang , Gaspar Rochette

Fourier representations play a central role in operator learning methods for partial differential equations and are increasingly being explored in quantum machine learning architectures. The classical fast Fourier transform (FFT),…

Quantum Physics · Physics 2026-03-19 Paolo Marcandelli , Stefano Mariani , Martina Siena , Stefano Markidis

One of the key challenges in the area of signal processing on graphs is to design transforms and dictionaries methods to identify and exploit structure in signals on weighted graphs. In this paper, we first generalize graph Fourier…

Computer Vision and Pattern Recognition · Computer Science 2019-02-28 Jiasong Wu , Fuzhi Wu , Qihan Yang , Youyong Kong , Xilin Liu , Yan Zhang , Lotfi Senhadji , Huazhong Shu

As a generalization of the Fourier transform, the fractional Fourier transform was introduced and has been further investigated both in theory and in applications of signal processing. We obtain a sampling theorem on shift-invariant spaces…

Functional Analysis · Mathematics 2013-02-12 Sinuk Kang

Convolutional neural networks owe much of their success to hard-coding translation equivariance. Quantum convolutional neural networks (QCNNs) have been proposed as near-term quantum analogues, but the relevant notion of translation depends…

Quantum Physics · Physics 2026-04-28 Dmitry Chirkov , Igor Lobanov

Hypercomplex Fourier transforms are increasingly used in signal processing for the analysis of higher-dimensional signals such as color images. A main stumbling block for further applications, in particular concerning filter design in the…

Classical Analysis and ODEs · Mathematics 2013-03-08 Roxana Bujack , Hendrik De Bie , Nele De Schepper , Gerik Scheuermann

The one-dimensional (1D) fractional Fourier transform (FRFT) generalizes the Fourier transform, offering significant advantages in the time-frequency analysis of non-stationary signals. While various 2D extensions exist, such as the 2D…

Signal Processing · Electrical Eng. & Systems 2026-03-03 Daxiang Li , Zhichao Zhang , Wei Yao

This paper introduces a novel time-frequency distribution, referred to as the Two-Dimensional Non-Separable Quadratic Phase Wigner Distribution (2D-NSQPWD), formulated within the framework of the Two-Dimensional Non-Separable Quadratic…

Signal Processing · Electrical Eng. & Systems 2025-09-25 Mukul Chauhan , Waseem Z. Lone , Amit K. Verma

We explain the orthogonal planes split (OPS) of quaternions based on the arbitrary choice of one or two linearly independent pure unit quaternions $f,g$. Next we systematically generalize the quaternionic Fourier transform (QFT) applied to…

Rings and Algebras · Mathematics 2013-06-10 Eckhard Hitzer

In this paper, a new variant to fractional signal processing is proposed known as the Reduced Order Fractional Fourier Transform. Various properties satisfied by its transformation kernel is derived. The properties associated with the…

Signal Processing · Electrical Eng. & Systems 2018-04-18 Sanjay Kumar

A discrete complexified quaternion Fourier transform is introduced. This is a generalization of the discrete quaternion Fourier transform to the case where either or both of the signal/image and the transform kernel are complex…

Numerical Analysis · Mathematics 2008-03-19 Salem Said , Nicolas Le Bihan , Stephen J. Sangwine

The quaternion offset linear canonical transform(QOLCT) has gained much popularity in recent years because of its applications in many areas, including color image and signal processing. At the same time the applications of Wigner-Ville…

Signal Processing · Electrical Eng. & Systems 2021-09-21 Mohammad Younus Bhat , Aamir Hamid Dar

This paper introduces Generalized Fourier transform (GFT) that is an extension or the generalization of the Fourier transform (FT). The Unilateral Laplace transform (LT) is observed to be the special case of GFT. GFT, as proposed in this…

Signal Processing · Electrical Eng. & Systems 2022-04-06 Pushpendra Singh , Anubha Gupta , Shiv Dutt Joshi

Wave equations are fundamental to describing a vast array of physical phenomena, yet their simulation in inhomogeneous media poses a computational challenge due to the highly oscillatory nature of the solutions. To overcome the high costs…

Machine Learning · Computer Science 2026-03-17 Yiyang Cai , Zixuan Qiu , Yunlu Shu , Jiamao Wu , Yingzhou Li , Tianyu Wang , Xi Chen

In this paper, we extend the coupled fractional Fourier transform of a complex valued functions to that of the quaternion valued functions on $\mathbb{R}^4$ and call it the quaternion coupled fractional Fourier transform (QCFrFT). We obtain…

General Mathematics · Mathematics 2023-10-02 Bivek Gupta , Amit K. Verma , Ravi P. Agarwal

The paper improves the accuracy of the one-dimensional fractional Fourier transform (FRFT) by leveraging closed Newton-Cotes quadrature rules. Using the weights derived from the Composite Newton-Cotes rules of order QN, we demonstrate that…

Numerical Analysis · Mathematics 2025-04-15 A. H. Nzokem

In this paper we investigate how the short-time Fourier transform can be extended in a Clifford setting. We prove some of the main properties of the Clifford short-time Fourier transform such as the orthogonality relation, the…

Classical Analysis and ODEs · Mathematics 2021-11-17 Antonino De Martino

The quantum Fourier transform (QFT), a quantum analog of the classical Fourier transform, has been shown to be a powerful tool in developing quantum algorithms. However, in classical computing there is another class of unitary transforms,…

Quantum Physics · Physics 2007-05-23 Amir Fijany , Colin P. Williams

In the present paper, we intent to enlarge the axiomatic framework of non-commutative quantum field theories (QFT). We consider QFT on non-commutative spacetimes in terms of the tempered ultrahyperfunctions of Sebasti\~ao e Silva…

Mathematical Physics · Physics 2008-02-23 Daniel H. T. Franco , José A. Lourenço , Luiz H. Renoldi