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We study partial derivatives on the product of two metric measure structures, in particular in connection with calculus via modules as proposed by the first named author. Our main results are 1) The extension to this non-smooth framework of…

Functional Analysis · Mathematics 2020-12-08 Nicola Gigli , Chiara Rigoni

We present a method of solving partial differential equations on the $n$-dimensional unit sphere using methods based on the continuous wavelet transform derived from approximate identities. We give an explicit analytical solution to the…

Analysis of PDEs · Mathematics 2025-07-08 Ilona Iglewska-Nowak , Piotr Stefaniak

The dual-tree complex wavelet transform (DT-CWT) is known to exhibit better shift-invariance than the conventional discrete wavelet transform. We propose an amplitude-phase representation of the DT-CWT which, among other things, offers a…

Information Theory · Computer Science 2013-07-23 Kunal Narayan Chaudhury , Michael Unser

Three problems for a discrete analogue of the Helmholtz equation are studied analytically using the plane wave decomposition and the Sommerfeld integral approach. They are: 1) the problem with a point source on an entire plane; 2) the…

Numerical Analysis · Mathematics 2021-02-15 A. V. Shanin , A. I. Korolkov

The fundamental solution (Green function) for the Cauchy problem of the space-time fractional diffusion equation is investigated with respect to its scaling and similarity properties, starting from its Fourier-Laplace representation. Then,…

Probability · Mathematics 2007-10-02 Francesco Mainardi

I discuss the nature of a Fractional Discrete Fourier Transform (FrDFT) described algorithmically by a combination of chirp transforms and ordinary DFTs. The transform is shown to be consistent with a continuous two-dimensional rotation…

General Mathematics · Mathematics 2019-10-01 Evan Zayas

The Fractional Fourier Transform (FrFT) has widespread applications in areas like signal analysis, Fourier optics, diffraction theory, etc. The Holomorphic Fractional Fourier Transform (HFrFT) proposed in the present paper may be used in…

Mathematical Physics · Physics 2019-05-13 William D. Kirwin , José Mourão , João P. Nunes , Thomas Thiemann

This paper presents an extended version of the article [Franz, S., Kopteva, N.: J. Differential Equations, 252 (2012)]. The main improvement compared to the latter is in that here we additionally estimate the mixed second-order derivative…

Analysis of PDEs · Mathematics 2022-12-23 Sebastian Franz , Natalia Kopteva

Using Pathak and Pathak techniques, the basic function $D^\alpha(u,v,w)$ associated with general novel fractional wavelet transform (GNFrWT)is defined and its properties are investigated. By using basic function $D^\alpha(u,v,w)$…

Functional Analysis · Mathematics 2014-05-01 Ashish Pathak , Prabhat Yadav , M M Dixit

A novel addition to the family of integral transforms, the quadratic phase Fourier transform (QPFT) embodies a variety of signal processing tools, including the Fourier transform (FT), fractional Fourier transform (FRFT), linear canonical…

Functional Analysis · Mathematics 2024-02-20 Aamir Hamid Dar

The $\alpha'$-deformed frame-like Double Field Theory (DFT) is a T-duality and gauge invariant extension of DFT in which generalized Green-Schwarz transformations provide a gauge principle that fixes the higher-derivative corrections. It…

High Energy Physics - Theory · Physics 2017-05-24 Walter H. Baron , Jose J. Fernandez-Melgarejo , Diego Marques , Carmen Nunez

Fourier methods well known in signal processing are applied to three-dimensional wave propagation problems. The Fourier transform of the Green function, when written explicitly in terms of a real-valued spatial frequency, consists of…

Optics · Physics 2014-01-21 Colin J. R. Sheppard , Shan Shan Kou , Jiao Lin

This note is a very basic introduction to wavelets. It starts with an orthogonal basis of piecewise constant functions, constructed by dilation and translation. The ``wavelet transform'' maps each $f(x)$ to its coefficients with respect to…

Numerical Analysis · Mathematics 2025-10-20 Gilbert Strang

The windowed quadratic phase Fourier transform (WQPFT) combines the localization capabilities of windowed transforms with the phase modulation structure of the quadratic phase Fourier transform (QPFT). This paper investigates fundamental…

Functional Analysis · Mathematics 2025-07-09 Sarga Varghese , Manab Kundu

Source wavelet estimation is the key in seismic signal processing for resolving subsurface structural properties. Homomorphic deconvolution using cepstrum analysis has been an effective method for wavelet estimation for decades. In general,…

Information Theory · Computer Science 2012-06-06 K. H. Miah , R. H. Herrera , M. van der Baan , M. D. Sacchi

In this survey we discuss derivatives of the Wright functions (of the first and the second kind) with respect to parameters. Differentiation of these functions leads to infinite power series with coefficient being quotients of the digamma…

General Mathematics · Mathematics 2022-12-21 Alexander Apelblat , Francesco Mainardi

In this paper, a fractional version of the Clifford-Fourier transform is introduced, depending on two numerical parameters. A series expansion for the kernel of the resulting integral transform is derived. In the case of even dimension,…

Classical Analysis and ODEs · Mathematics 2012-09-27 Hendrik De Bie , Nele De Schepper

The degree by which a function can be differentiated need not be restricted to integer values. Usually most of the field equations of physics are taken to be second order, curiosity asks what happens if this is only approximately the case…

General Relativity and Quantum Cosmology · Physics 2014-06-23 Mark D. Roberts

A class of second order approximations, called the weighted and shifted Gr\"{u}nwald difference operators, are proposed for Riemann-Liouville fractional derivatives, with their effective applications to numerically solving space fractional…

Numerical Analysis · Mathematics 2015-04-27 WenYi Tian , Han Zhou , Weihua Deng

The setting is the representation theory of a simply connected, semisimple algebraic group over a field of positive characteristic. There is a natural transformation from the wall-crossing functor to the identity functor. The kernel of this…

Representation Theory · Mathematics 2010-02-09 Kevin J. Carlin