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We generalize the recent invariant polytope algorithm for computing the joint spectral radius and extend it to a wider class of matrix sets. This, in particular, makes the algorithm applicable to sets of matrices that have finitely many…

Numerical Analysis · Mathematics 2015-02-05 Nicola Guglielmi , Vladimir Yu. Protasov

The Hilbert transform is a multiplier operator and is widely used in the theory of Fourier transforms. The Hilbert transform was the motivation for the development of modern harmonic analysis. Its discrete version is also widely used in…

Functional Analysis · Mathematics 2026-01-12 Rashid Aliev , Amil Jabiyev

We study Fourier integral operators with Shubin amplitudes and quadratic phase functions associated to twisted graph Lagrangians with respect to symplectic matrices. We factorize such an operator as the composition of a Weyl…

Analysis of PDEs · Mathematics 2019-03-07 Marco Cappiello , René Schulz , Patrik Wahlberg

Inspired by the success of recent data augmentation methods for signals which act on time-frequency representations, we introduce an operator which convolves the short-time Fourier transform of a signal with a specified kernel. Analytical…

Functional Analysis · Mathematics 2025-10-17 Simon Halvdansson

We introduce and study weighted spaces of functions with mixed norm on the upper half-plane, defined in terms of Fourier transform. We give a characterization of analytic functions within these spaces, and in particular, we provide an…

Functional Analysis · Mathematics 2024-12-30 Zhirayr Avetisyan , Alexey Karapetyants , Irina Smirnova

In this paper, we address the random sampling problem for the class of Mellin band-limited functions BT which is concentrated on a bounded cube. It is established that any function in BT can be approximated by an element in a…

Functional Analysis · Mathematics 2023-05-25 Shivam Bajpeyi , Dhiraj Patel , S. Sivananthan

The problem of recovering a signal of finite duration from a piece of its Fourier transform was solved at Bell Labs in the $1960$'s, by exploiting a "miracle": a certain naturally appearing integral operator commutes with an explicit…

Spectral Theory · Mathematics 2017-01-20 F. Alberto Grünbaum , Inés Pacharoni , Ignacio Nahuel Zurrián

This is a survey on a notion of invariant operators, or Fourier multipliers on Hilbert spaces. This concept is defined with respect to a fixed partition of the space into a direct sum of finite dimensional subspaces. In particular this…

Functional Analysis · Mathematics 2018-05-01 Julio Delgado , Michael Ruzhansky

Most of the known Fourier transforms associated with the equations of mathematical physics have a trivial kernel, and an inversion formula as well as the Parseval equality are fulfilled. In other words, the system of the eigenfunctions…

Analysis of PDEs · Mathematics 2024-12-18 Aleksei Gorshkov

This research includes the study of some positive sampling Kantorovich operators (SK operators) and their convergence properties. A comprehensive analysis of both local and global approximation properties is presented using sampling…

Computer Vision and Pattern Recognition · Computer Science 2025-08-21 Digvijay Singh , Rahul Shukla , Karunesh Kumar Singh

This paper develops a threshold model with a time-varying threshold, represented using a wavelet series expansion. The model adequately captures irregular and abrupt variations, as well as smooth changes in the threshold parameter, allowing…

Methodology · Statistics 2026-05-19 Rhea Davis , N. Balakrishna

Injectivity of the continuous wavelet transform acting on a square integrable signal is proved under weak conditions on the Fourier transform of the wavelet, namely that it is nonzero somewhere in almost every direction. For a bounded…

Classical Analysis and ODEs · Mathematics 2011-03-18 H. -Q. Bui , R. S. Laugesen

Consider a non-negative, self-adjoint, maximally subelliptic operator on a compact manifold. We show that the spectral multiplier is a singular integral operator under an appropriate Mihlin-H\"ormander type condition. We establish the…

Functional Analysis · Mathematics 2025-01-13 Lingxiao Zhang

Band-limited functions are fundamental objects that are widely used in systems theory and signal processing. In this paper we refine a recent nonparametric, nonasymptotic method for constructing simultaneous confidence regions for…

Machine Learning · Statistics 2026-01-27 Balázs Csanád Csáji , Bálint Horváth

We investigate the application of windowed Fourier frames (WFFs) to the numerical solution of partial differential equations, focussing on elliptic equations. The action of a partial differential operator (PDO) on a windowed plane wave is…

Analysis of PDEs · Mathematics 2010-09-13 Samir K. Bhowmik , Christiaan C. Stolk

The spectrum and eigenstates of any field quadrature operator restricted to a finite number $N$ of photons are studied, in terms of the Hermite polynomials. By (naturally) defining \textit{approximate} eigenstates, which represent highly…

Quantum Physics · Physics 2015-03-13 Emilio Pisanty , Eduardo Nahmad-Achar

Quantum signal processing (QSP) represents a real scalar polynomial of degree $d$ using a product of unitary matrices of size $2\times 2$, parameterized by $(d+1)$ real numbers called the phase factors. This innovative representation of…

Quantum Physics · Physics 2024-12-11 Yulong Dong , Lin Lin , Hongkang Ni , Jiasu Wang

This paper introduces the concept of Bessel multipliers. These operators are defined by a fixed multiplication pattern, which is inserted between the Analysis and synthesis operators. The proposed concept unifies the approach used for Gabor…

Functional Analysis · Mathematics 2007-05-23 Peter Balazs

A new characterization of the singular packing subspaces of general bounded self-adjoint operators is presented, which is used to show that the set of operators whose spectral measures have upper packing dimension equal to one is a…

Mathematical Physics · Physics 2016-04-30 Silas L. Carvalho , César R. de Oliveira

In this paper we study the $L^p$-$L^q$ boundedness of the Fourier multipliers in the setting where the underlying Fourier analysis is introduced with respect to the eigenfunctions of an anharmonic oscillator $A$. Using the notion of a…

Analysis of PDEs · Mathematics 2021-05-19 M. Chatzakou , V. Kumar
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