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We consider how some methods of uniform and nonuniform interpolation by translates of radial basis functions -- specifically the so-called general multiquadrics -- perform in the presence of certain types of noise. These techniques provide…

Classical Analysis and ODEs · Mathematics 2018-02-14 Jean-Luc Bouchot , Keaton Hamm

We prove a.s. (almost sure) unisolvency of interpolation by continuous random sampling with respect to any given density, in spaces of multivariate a.e. (almost everywhere) analytic functions. Examples are given concerning polynomial and…

Numerical Analysis · Mathematics 2023-03-27 Francesco Dell'Accio , Alvise Sommariva , Marco Vianello

We give a construction of radial Fourier interpolation formulas in dimensions 3 and 4 using Maass--Poincar\'e type series. As a corollary we obtain explicit formulas for the basis functions of these interpolation formulas in terms of what…

Number Theory · Mathematics 2025-10-08 Danylo Radchenko , Qihang Sun

Let $S_\lambda F(x)$ be the spherical partial sums of the multiple Fourier series of function $F\in L_2(\mathbb{T}^N)$. We prove almost-everywhere convergence $S_\lambda F(x)\rightarrow F(x)$ for functions in Sobolev spaces…

Analysis of PDEs · Mathematics 2020-01-22 Ravshan Ashurov

Let $A$ be a square complex matrix, $z_1$, ..., $z_{n}\in\mathbb C$ be (possibly repetitive) points of interpolation, $f$ be analytic in a neighborhood of the convex hull of the union of the spectrum of $A$ and the points $z_1$, ...,…

Numerical Analysis · Mathematics 2019-02-19 V. G. Kurbatov , I. V. Kurbatova

We establish best possible pointwise (up to a constant multiple) estimates for approximation, on a finite interval, by polynomials that satisfy finitely many (Hermite) interpolation conditions, and show that these estimates cannot be…

Classical Analysis and ODEs · Mathematics 2021-01-07 Kirill A. Kopotun , Dany Leviatan , Igor A. Shevchuk

We prove a finiteness principle for interpolation of data by nonnegative Cm functions. Our result raises the hope that one can start to understand constrained interpolation problems in which e.g. the interpolating function F is required to…

Classical Analysis and ODEs · Mathematics 2016-03-09 Charles Fefferman , Arie Israel , Garving K. Luli

We consider a real interpolation method defined by means of slowly varying functions. We present some reiteration formulae including so called $L$ or $R$ limiting interpolation spaces. These spaces arise naturally in reiteration formulae…

Functional Analysis · Mathematics 2021-09-24 Leo R. Ya Doktorski

We study Pad\'{e} interpolation at the node $z=0$ of functions $f(z)=\sum_{m=0}^{\infty} f_m z^m$, analytic in a neighbourhood of this node, by amplitude and frequency operators (sums) of the form $$ \sum_{k=1}^n \mu_k h(\lambda_k z),…

Classical Analysis and ODEs · Mathematics 2016-03-08 Petr Chunaev , Vladimir Danchenko

Motivated by recent works by Radchenko and Viazovska and by Ramos and Sousa, we find sufficient conditions for a pair of discrete subsets of the real line to be a uniqueness or a non-uniqueness pair for the Fourier transform. These…

Classical Analysis and ODEs · Mathematics 2023-06-27 Aleksei Kulikov , Fedor Nazarov , Mikhail Sodin

We derive a tight upper bound on the probability over $\mathbf{x}=(x_1,\dots,x_\mu) \in \mathbb{Z}^\mu$ uniformly distributed in $ [0,m)^\mu$ that $f(\mathbf{x}) = 0 \bmod N$ for any $\mu$-linear polynomial $f \in…

Discrete Mathematics · Computer Science 2022-05-06 Benedikt Bünz , Ben Fisch

We completely classify Fourier summation formulas of the form $$ \int_{\mathbb{R}} \widehat{\varphi}(t) d\mu(t)=\sum_{n=0}^{\infty} a(\lambda_n)\varphi(\lambda_n), $$ that hold for any test function $\varphi$, where $\widehat\varphi$ is the…

Classical Analysis and ODEs · Mathematics 2025-04-04 Felipe Gonçalves , Guilherme Vedana

An algorithm for generating interpolants for formulas which are conjunctions of quadratic polynomial inequalities (both strict and nonstrict) is proposed. The algorithm is based on a key observation that quadratic polynomial inequalities…

Logic in Computer Science · Computer Science 2016-11-14 Ting Gan , Liyun Dai , Bican Xia , Naijun Zhan , Deepak Kapur , Mingshuai Chen

We present an $\ell^2_2+\ell_1$-regularized discrete least squares approximation over general regions under assumptions of hyperinterpolation, named hybrid hyperinterpolation. Hybrid hyperinterpolation, using a soft thresholding operator…

Numerical Analysis · Mathematics 2024-07-08 Congpei An , Jiashu Ran , Alvise Sommariva

The meshless/meshfree radial basis function (RBF) method is a powerful technique for interpolating scattered data. But, solving large RBF interpolation problems without fast summation methods is computationally expensive. For RBF…

Numerical Analysis · Mathematics 2016-06-27 Wei Zhao , Martin Stoll

We find sufficient conditions for a discrete sequence to be interpolating or sampling for certain generalized Bergman spaces on open Riemann surfaces. As in previous work of Bendtsson, Ortega-Cerda, Seip, Wallsten and others, our conditions…

Complex Variables · Mathematics 2007-05-23 Alexander P. Schuster , Dror Varolin

Given a finite number of samples of a continuous set-valued function F, mapping an interval to compact subsets of the real line, we develop good approximations of F, which can be computed efficiently.

Numerical Analysis · Mathematics 2022-09-01 Qusay Muzaffar , Nira Dyn , David Levin

We prove novel results on interpolation of Fredholm operators including an abstract factorization theorem. The main result of this paper provides sufficient conditions on the parameters $\theta \in (0,1)$ and $q\in \lbrack 1,\infty ]$ under…

Functional Analysis · Mathematics 2014-09-01 I. Asekritova , N. Kruglyak , M. Mastyło

We give an estimate of the general divided differences $[x_0,\dots,x_m;f]$, where some of the $x_i$'s are allowed to coalesce (in which case, $f$ is assumed to be sufficiently smooth). This estimate is then applied to significantly…

Classical Analysis and ODEs · Mathematics 2019-01-15 K. A. Kopotun , D. Leviatan , I. A. Shevchuk

Viazovska's solution of the sphere packing problem in eight dimensions is based on a remarkable construction of certain special functions using modular forms. Great mathematics has consequences far beyond the problems that originally…

Metric Geometry · Mathematics 2024-07-23 Henry Cohn