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We introduce a new method for the reconstruction of a function from linear measurements by means of oblique projections. The space spanned by the measurement vectors may be different from the subspace in which the function is reconstructed.…

Numerical Analysis · Mathematics 2013-12-09 Peter Berger , Karlheinz Gröchenig

We introduce a method to reconstruct an element of a Hilbert space in terms of an arbitrary finite collection of linearly independent reconstruction vectors, given a finite number of its samples with respect to any Riesz basis. As we…

Numerical Analysis · Mathematics 2010-12-01 Ben Adcock , Anders C. Hansen

We consider the problem of recovering a compactly-supported function from a finite collection of pointwise samples of its Fourier transform taking nonuniformly. First, we show that under suitable conditions on the sampling frequencies -…

Numerical Analysis · Mathematics 2014-04-08 Ben Adcock , Milana Gataric , Anders C. Hansen

Contrary to the traditional pursuit of research on nonuniform sampling of bandlimited signals, the objective of the present paper is not to find sampling conditions that permit perfect reconstruction, but to perform the best possible signal…

Signal Processing · Electrical Eng. & Systems 2024-04-05 Nguyen T. Thao , Dominik Rzepka , Marek Miskowicz

Under investigation is the problem of finding the best approximation of a function in a Hilbert space subject to convex constraints and prescribed nonlinear transformations. We show that in many instances these prescriptions can be…

Functional Analysis · Mathematics 2021-06-17 Patrick L. Combettes , Zev C. Woodstock

This paper is concerned with function reconstruction from samples. The sampling points used in several approaches are (1) structured points connected with fast algorithms or (2) unstructured points coming from, e.g., an initial random draw…

Numerical Analysis · Mathematics 2023-06-07 Felix Bartel , Lutz Kämmerer , Daniel Potts , Tino Ullrich

We study the problem of recovering an unknown compactly-supported multivariate function from samples of its Fourier transform that are acquired nonuniformly, i.e. not necessarily on a uniform Cartesian grid. Reconstruction problems of this…

Numerical Analysis · Mathematics 2022-05-04 Ben Adcock , Milana Gataric , José Luis Romero

We construct a least squares approximation method for the recovery of complex-valued functions from a reproducing kernel Hilbert space on $D \subset \mathbb{R}^d$. The nodes are drawn at random for the whole class of functions and the error…

Numerical Analysis · Mathematics 2021-04-05 Lutz Kämmerer , Tino Ullrich , Toni Volkmer

Generalized sampling is a recently developed linear framework for sampling and reconstruction in separable Hilbert spaces. It allows one to recover any element in any finite-dimensional subspace given finitely many of its samples with…

Numerical Analysis · Mathematics 2013-01-15 Ben Adcock , Anders C. Hansen , Clarice Poon

In this note we study the problem of sampling and reconstructing signals which are assumed to lie on or close to one of several subspaces of a Hilbert space. Importantly, we here consider a very general setting in which we allow infinitely…

Information Theory · Computer Science 2009-12-02 Thomas Blumensath

An axiomatic approach to signal reconstruction is formulated, involving a sample consistent set and a guiding set, describing desired reconstructions. New frame-less reconstruction methods are proposed, based on a novel concept of a…

Information Theory · Computer Science 2017-02-14 Andrew Knyazev , Akshay Gadde , Hassan Mansour , Dong Tian

We consider the problem of learning an unknown, possibly nonlinear operator between separable Hilbert spaces from supervised data. Inputs are drawn from a prescribed probability measure on the input space, and outputs are (possibly noisy)…

Numerical Analysis · Mathematics 2025-12-15 John Turnage , Matthew Lowery , John Jakeman , Zachary Morrow , Akil Narayan , Varun Shankar

We present a scalable low dimensional manifold model for the reconstruction of noisy and incomplete hyperspectral images. The model is based on the observation that the spatial-spectral blocks of a hyperspectral image typically lie close to…

Computer Vision and Pattern Recognition · Computer Science 2018-03-28 Wei Zhu , Zuoqiang Shi , Stanley Osher

Given a set of vectors (the data) in a Hilbert space H, we prove the existence of an optimal collection of subspaces minimizing the sum of the square of the distances between each vector and its closest subspace in the collection. This…

Classical Analysis and ODEs · Mathematics 2008-02-07 Akram Aldroubi , Carlos Cabrelli , Ursula Molter

We consider the inverse problem of reconstructing general solutions to the Helmholtz equation on some domain $\Omega$ from their values at scattered points $x_1,\dots,x_n\subset \Omega$. This problem typically arises when sampling acoustic…

Numerical Analysis · Mathematics 2014-04-04 Gilles Chardon , Albert Cohen , Laurent Daudet

We demonstrate that it is possible to construct operators that stabilize the constraint-satisfying subspaces of computational problems in their Ising representations. We provide an explicit recipe to construct unitaries and associated…

This paper is concerned with the numerical minimization of energy functionals in Hilbert spaces involving convex constraints coinciding with a semi-norm for a subspace. The optimization is realized by alternating minimizations of the…

Numerical Analysis · Mathematics 2007-12-17 Massimo Fornasier , Carola-Bibiane Schönlieb

We propose a method for solving constrained fixed point problems involving compositions of Lipschitz pseudo contractive and firmly nonexpansive operators in Hilbert spaces. Each iteration of the method uses separate evaluations of these…

Optimization and Control · Mathematics 2011-01-10 Luis M. Briceño-Arias

We study the problem of stable reconstruction of the short-time Fourier transform from samples taken from trajectories in $\R^2$. We first consider the interplay between relative density of the trajectory and the reconstruction property.…

Functional Analysis · Mathematics 2021-12-06 Michael Speckbacher

The method of superposition is proposed in combination with a sparse $\ell_1$ optimisation algorithm with the aim of finding a sparse basis to accurately reconstruct the structural vibrations of a radiating object from a set of acoustic…

Computational Physics · Physics 2016-01-20 Nadia M. Abusag , David J. Chappell
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