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The spherical mean transform associates to a function $f$ its integral averages over all spheres. We consider the spherical mean transform for functions supported in the unit ball $\mathbb{B}$ in $\mathbb{R}^n$ for odd $n$, with the centers…

Classical Analysis and ODEs · Mathematics 2024-06-25 Divyansh Agrawal , Gaik Ambartsoumian , Venkateswaran P. Krishnan , Nisha Singhal

We decompose the discrete bilinear spherical averaging operator into simpler operators in several ways. This leads to a wide array of extensions, such as to the simplex averaging operator, and applications, such as to operator bounds.

Classical Analysis and ODEs · Mathematics 2023-06-27 Theresa C. Anderson , Angel V. Kumchev , Eyvindur A. Palsson

We consider an inverse problem arising in thermo-/photo- acoustic tomography that amounts to reconstructing a function $f$ from its circular or spherical means with the centers lying on a given measurement surface. (Equivalently, these…

Analysis of PDEs · Mathematics 2015-09-02 Leonid Kunyansky

We introduce the notion of regular operator mappings of several variables generalising the notion of spectral function. This setting is convenient for studying maps more general than what can be obtained from the functional calculus, and it…

Functional Analysis · Mathematics 2014-07-23 Frank Hansen

In this article, we impose a new class of fractional analytic functions in the open unit disk. By considering this class, we define a fractional operator, which is generalized Salagean and Ruscheweyh differential operators. Moreover, by…

Complex Variables · Mathematics 2016-02-26 Zainab E. Abdulnaby , Rabha W. Ibrahim , Adem Kilicman

We investigate a linear operator associated with a functional equation that arises from studying some class of invariant measures under multidimensional transformations. By examining its iterates, we derive an explicit solution formula for…

Functional Analysis · Mathematics 2026-03-09 Oleksandr V. Maslyuchenko , Janusz Morawiec , Thomas Zürcher

The scalar functional determinants on sectors of the two-dimensional disc and spherical cap are determined for arbitrary angles (rational factors of $\pi$). The wholesphere and hemisphere expressions are also given, in low dimensions, for…

High Energy Physics - Theory · Physics 2009-10-22 J. S. Dowker

We review some aspects of the theory of spherical Bessel functions and Struve functions by means of an operational procedure essentially of umbral nature, capable of providing the straightforward evaluation of their definite integrals and…

Classical Analysis and ODEs · Mathematics 2014-05-15 D. Babusci , G. Dattoli , K. Gorska , K. A. Penson

A new approach to normal operators in real Hilbert spaces is discussed, and a spectral representation is obtained, derived directly from the complex case. The results are then applied to quaternionic normal operators, regarded as a special…

Functional Analysis · Mathematics 2025-07-28 Florian-Horia Vasilescu

We present an approach how to obtain solutions of arbitrary linear operator equation for unknown functions. The particular solution can be represented by the infinite operator series (Cyclic Operator Decomposition), which acts the…

Spectral Theory · Mathematics 2012-06-19 Ivan Gonoskov

We investigate a generalized spherical means operator, viz. generalized spherical mean Radon transform, acting on radial functions. We establish an integral representation of this operator and find precise estimates of the corresponding…

Classical Analysis and ODEs · Mathematics 2018-11-06 Óscar Ciaurri , Adam Nowak , Luz Roncal

The standard formula for the change in the effective action under a conformal transformation is extended to the case when the boundary is piecewise smooth. We then find the functional determinants of the scalar Laplacian on regions of the…

High Energy Physics - Theory · Physics 2010-04-06 J. S. Dowker

Let $\mathbb{P}$ be the complete metric space consisting of positive invertible operators on an infinite-dimensional Hilbert space with the Thompson metric. We introduce the notion of operator means of probability measures on $\mathbb{P}$,…

Functional Analysis · Mathematics 2019-01-15 Fumio Hiai , Yongdo Lim

Many shape analysis methods treat the geometry of an object as a metric space that can be captured by the Laplace-Beltrami operator. In this paper, we propose to adapt the classical Hamiltonian operator from quantum mechanics to the field…

Graphics · Computer Science 2017-06-27 Yoni Choukroun , Alon Shtern , Alex Bronstein , Ron Kimmel

We use the classical Fourier analysis to introduce analytic families of weighted differential operators on the unit sphere. These operators are polynomial functions of the usual Beltrami-Laplace operator. New inversion formulas are obtained…

Functional Analysis · Mathematics 2020-05-12 Boris Rubin

Linear operations on coefficients in the spherical harmonics (SH) transform domain that again yield SH-domain coefficients are an important toolset in many disciplines of research and engineering. They comprise rotations, spatially…

Audio and Speech Processing · Electrical Eng. & Systems 2021-11-30 Maximilian Kentgens , Peter Jax

The aim of this work is to define a continuous functional calculus in quaternionic Hilbert spaces, starting from basic issues regarding the notion of spherical spectrum of a normal operator. As properties of the spherical spectrum suggest,…

Functional Analysis · Mathematics 2013-06-17 Riccardo Ghiloni , Valter Moretti , Alessandro Perotti

This paper provides an approach to establishing the calculus method from the concept of mean, i.e., average. This approach is from a statistics perspective and can help calculus learners understand calculus ideas and analyze a function…

History and Overview · Mathematics 2014-06-12 Samuel S. P. Shen , Dov Zazkis , Kimberly Leung , Chris Rasmussen

Let $B(H)$ be the algebra of all bounded operators on a Hilbert space $H$. Let $T=V|T|$ be the polar decomposition of an operator $T\in B(H)$. The mean transform of $T$ is defined by $M(T)=\frac{T+|T|V}{2}$. In this paper, we discuss…

Functional Analysis · Mathematics 2022-07-28 Fadil Chabbabi , Maëva Ostermann

Solving analytic systems using inversion can be implemented in a variety of ways. One method is to use Lagrange inversion and variations. Here we present a different approach, based on dual vector fields. For a function analytic in a…

Classical Analysis and ODEs · Mathematics 2011-02-11 Ph. Feinsilver , R. Schott