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The need to Fourier transform data sets with irregular sampling is shared by various domains of science. This is the case for example in astronomy or sismology. Iterative methods have been developed that allow to reach approximate…

Numerical Analysis · Mathematics 2024-01-23 Guy Perrin

In the present paper, a wavelet family over the $n$-dimensional sphere is constructed such that for each scale the wavelet is a polynomial and the inverse wavelet transform of a continuous function converges in the supremum norm.

Classical Analysis and ODEs · Mathematics 2018-06-22 Ilona Iglewska-Nowak

Many representation systems on the sphere have been proposed in the past, such as spherical harmonics, wavelets, or curvelets. Each of these data representations is designed to extract a specific set of features, and choosing the best fixed…

Instrumentation and Methods for Astrophysics · Physics 2019-01-23 Florent Sureau , Felix Voigtlaender , Malte Wust , Jean-Luc Starck , Gitta Kutyniok

In this paper, we are concerned with $n$-dimensional spherical wavelets derived from the theory of approximate identities. For nonzonal bilinear wavelets introduced by Ebert \emph{et al.} in 2009 we prove isometry and Euclidean limit…

Functional Analysis · Mathematics 2018-03-07 Ilona Iglewska-Nowak

We investigate here a generalized construction of spherical wavelets/needlets which admits extra-flexibility in the harmonic domain, i.e., it allows the corresponding support in multipole (frequency) space to vary in more general forms than…

Probability · Mathematics 2021-09-14 Claudio Durastanti , Domenico Marinucci , Anna Paola Todino

We devise fast and provably accurate algorithms to transform between an $N\times N \times N$ Cartesian voxel representation of a three-dimensional function and its expansion into the {ball harmonics}, that is, the eigenbasis of the…

Numerical Analysis · Mathematics 2025-05-02 Joe Kileel , Nicholas F. Marshall , Oscar Mickelin , Amit Singer

Wavelets and their associated transforms are highly efficient when approximating and analyzing one-dimensional signals. However, multivariate signals such as images or videos typically exhibit curvilinear singularities, which wavelets are…

Numerical Analysis · Mathematics 2017-11-15 Gitta Kutyniok , Wang-Q Lim , Rafael Reisenhofer

Graphite is an example of a layered material that can be bent to form fullerenes which promise important applications in electronic nanodevices. The spheroidal geometry of a slightly elliptically deformed sphere was used as a possible…

Materials Science · Physics 2009-11-13 R. Pincak

We propose a method of solving partial differential equations on the $n$-dimen\-sional unit sphere with methods based on the continuous wavelet transform derived from approximate identities.

Mathematical Physics · Physics 2021-09-06 {Ilona Iglewska-Nowak , Piotr Stefaniak

We prove a novel method for the embedding of a 3-fold rotationally symmetric sphere-type mesh onto a subset of the plane with 3-fold rotational symmetry. The embedding is free-boundary with the only additional constraint on the image set is…

Computational Geometry · Computer Science 2024-06-12 Tom Gilat , Ben Gilat

The continuous wavelet transform has become a widely used tool in applied science during the last decade. In this article we discuss some generalizations coming from actions of closed subgroups of $\mathrm{GL}(n,\mathbb{R})$ acting on…

Functional Analysis · Mathematics 2007-05-23 R. Fabec , G. Olafsson

New elliptic cylindrical wavelets are introduced, which exploit the relationship between analysing filters and Floquet's solution of Mathieu differential equations. It is shown that the transfer function of both multiresolution filters is…

Classical Analysis and ODEs · Mathematics 2015-04-24 M. M. S. Lira , H. M. de Oliveira , R. J. Cintra , R. M. Campello de Souza

Wavelet analysis and compression tools are reviewed and different applications to study MHD and plasma turbulence are presented. We introduce the continuous and the orthogonal wavelet transform and detail several statistical diagnostics…

Plasma Physics · Physics 2015-10-21 Marie Farge , Kai Schneider

We present a new proof of a theorem of Mallat which describes a construction of wavelets starting from a quadrature mirror filter. Our main innovation is to show how the scaling function associated to the filter can be used to identify a…

Functional Analysis · Mathematics 2007-05-23 Nadia S. Larsen , Iain Raeburn

We identify the result of the continuous wavelet transform with the difference of solutions of two hyperbolic partial differential equations, for which wavelet's shift and scale are considered as independent variables on 2D plane. The…

Functional Analysis · Mathematics 2015-11-11 Eugene B. Postnikov , Vineet K. Singh

We propose a new method for (global) Hurst exponent determination based on wavelets. Using this method, we analyze synthetic data with predefined Hurst exponents, fracture surfaces and data from economy. The results are compared with those…

Materials Science · Physics 2010-05-04 Ingve Simonsen , Alex Hansen , Olav Magnar Nes

This work presents the construction of a novel spherical wavelet basis designed for incomplete spherical datasets, i.e. datasets which are missing in a particular region of the sphere. The eigenfunctions of the Slepian spatial-spectral…

Information Theory · Computer Science 2023-04-24 Patrick J. Roddy , Jason D. McEwen

Wavelets are widely used in various disciplines to analyse signals both in space and scale. Whilst many fields measure data on manifolds (i.e., the sphere), often data are only observed on a partial region of the manifold. Wavelets are a…

Information Theory · Computer Science 2023-04-24 Patrick J. Roddy

We introduce a new numerical method for solving time-harmonic acoustic scattering problems. The main focus is on plane waves scattered by smoothly varying material inhomogeneities. The proposed method works for any frequency $\omega$, but…

Numerical Analysis · Mathematics 2022-01-14 Anton Arnold , Sjoerd Geevers , Ilaria Perugia , Dmitry Ponomarev

A fast algorithm is developed for the directional correlation of scalar band-limited signals and band-limited steerable filters on the sphere. The asymptotic complexity associated to it through simple quadrature is of order O(L^5), where 2L…

Astrophysics · Physics 2011-02-11 Y. Wiaux , L. Jacques , P. Vielva , P. Vandergheynst
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