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Let $M$ be the space of real $n\times m$ matrices which can be identified with the Euclidean space $R^{nm}$. We introduce continuous wavelet transforms on $M$ with a multivalued scaling parameter represented by a positive definite symmetric…

Functional Analysis · Mathematics 2007-05-23 G. Olafsson , E. Ournycheva , B. Rubin

We investigate an interpolation/extrapolation method that, given scattered observations of the Fourier transform, approximates its inverse. The interpolation algorithm takes advantage of modelling the available data via a shape-driven…

Numerical Analysis · Mathematics 2021-09-22 Emma Perracchione , Anna Maria Massone , Michele Piana

Deep neural networks excel at learning the training data, but often provide incorrect and confident predictions when evaluated on slightly different test examples. This includes distribution shifts, outliers, and adversarial examples. To…

Recent years have seen a surge in data-driven surrogates for dynamical systems that can be orders of magnitude faster than numerical solvers. However, many machine learning-based models such as neural operators exhibit spectral bias,…

Machine Learning · Computer Science 2026-05-07 Xuesong Wang , Michael Groom , Rafael Oliveira , He Zhao , Terence O'Kane , Edwin V. Bonilla

It is common to have to process signals, whose values are points on the 3-D sphere. We consider a Tikhonov-type regularization model to smoothen or interpolate sphere-valued signals defined on arbitrary graphs. We propose a convex…

Optimization and Control · Mathematics 2022-07-26 Laurent Condat

A wavelet-based method for compression of three-dimensional simulation data is presented and its software framework is described. It uses wavelet decomposition and subsequent range coding with quantization suitable for floating-point data.…

Computational Physics · Physics 2022-01-06 Dmitry Kolomenskiy , Ryo Onishi , Hitoshi Uehara

The main contribution of this paper is twofold: On the one hand, a general framework for performing Hermite interpolation on Riemannian manifolds is presented. The method is applicable, if algorithms for the associated Riemannian…

Numerical Analysis · Mathematics 2021-12-20 Ralf Zimmermann

Convolutional network are the de-facto standard for analysing spatio-temporal data such as images, videos, 3D shapes, etc. Whilst some of this data is naturally dense (for instance, photos), many other data sources are inherently sparse.…

Neural and Evolutionary Computing · Computer Science 2017-06-06 Benjamin Graham , Laurens van der Maaten

Estimating accurate high-dimensional transformations remains very challenging, especially in a clinical setting. In this paper, we introduce a multiscale parameterization of deformations to enhance registration and atlas estimation in the…

Optimization and Control · Mathematics 2025-01-31 Fleur Gaudfernau , Eléonore Blondiaux , Stéphanie Allassonnière , Erwan Le Pennec

We consider scattered data approximation on product regions of equal and different dimensionality. On each of these regions, we assume quasi-uniform but unstructured data sites and construct optimal sparse grids for scattered data…

Numerical Analysis · Mathematics 2026-04-24 Michael Griebel , Helmut Harbrecht , Michael Multerer

The notion of wavelets is defined. It is briefly described {\it what} are wavelets, {\it how} to use them, {\it when} we do need them, {\it why} they are preferred and {\it where} they have been applied. Then one proceeds to the…

High Energy Physics - Phenomenology · Physics 2008-11-26 I. M. Dremin

A new approach of solving the ill-conditioned inverse problem for analytical continuation is proposed. The root of the problem lies in the fact that even tiny noise of imaginary-time input data has a serious impact on the inferred…

Strongly Correlated Electrons · Physics 2017-06-28 Junya Otsuki , Masayuki Ohzeki , Hiroshi Shinaoka , Kazuyoshi Yoshimi

We consider continuous-time sparse stochastic processes from which we have only a finite number of noisy/noiseless samples. Our goal is to estimate the noiseless samples (denoising) and the signal in-between (interpolation problem). By…

Machine Learning · Computer Science 2015-06-11 Arash Amini , Ulugbek S. Kamilov , Emrah Bostan , Michael Unser

In this contribution, we propose a detailed study of interpolation-based data-driven methods that are of relevance in the model reduction and also in the systems and control communities. The data are given by samples of the transfer…

Numerical Analysis · Mathematics 2023-01-13 Quirin Aumann , Ion Victor Gosea

The analysis of surface wave dispersion curves is a way to infer the vertical distribution of shear-wave velocity. The range of applicability is extremely wide going, for example, from seismological studies to geotechnical characterizations…

Geophysics · Physics 2021-02-25 Giulio Vignoli , Julien Guillemoteau , Jeniffer Barreto , Matteo Rossi

We propose a convex and fast signal reconstruction method for block sparsity under arbitrary linear transform with unknown block structure. The proposed method is a generalization of the similar existing method and can reconstruct signals…

Machine Learning · Computer Science 2024-02-14 Takanobu Furuhashi , Hidekata Hontani , Tatsuya Yokota

We suggest an adaptive sampling rule for obtaining information from noisy signals using wavelet methods. The technique involves increasing the sampling rate when relatively high-frequency terms are incorporated into the wavelet estimator,…

Statistics Theory · Mathematics 2007-06-13 Peter Hall , Spiridon Penev

Anisotropic decompositions using representation systems such as curvelets, contourlet, or shearlets have recently attracted significantly increased attention due to the fact that they were shown to provide optimally sparse approximations of…

Functional Analysis · Mathematics 2015-03-17 Gitta Kutyniok

Basing on invariant properties of universal multifractals we propose a simple algorithm for interpolation of multifractal densities. The algorithm admits generalization to a multidimensional case. Analitically obtained are multifractal…

chao-dyn · Physics 2007-05-23 V. G. Bar'yahtar , V. Yu. Gonchar , D. Schertzer , V. V. Yanovsky

In this paper we analyze two-dimensional wavelet reconstructions from Fourier samples within the framework of generalized sampling. For this, we consider both separable compactly-supported wavelets and boundary wavelets. We prove that the…

Functional Analysis · Mathematics 2014-03-25 Ben Adcock , Anders C. Hansen , Gitta Kutyniok , Jackie Ma