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It is shown how it is possible to reconstruct the initial state of a one-dimensional system by measuring sequentially two conjugate variables. The procedure relies on the quasi-characteristic function, the Fourier-transform of the Wigner…

Quantum Physics · Physics 2013-01-07 Antonio Di Lorenzo

A new approach for solving the optical inverse problem of quantitative photoacoustic tomography is introduced, which interpolates between the well-known diffusion approximation and a radiative transfer equation based model. The proposed…

Computational Physics · Physics 2025-09-09 David J. Chappell

Over decades, the time evolution of Wigner functions along classical Hamiltonian flows has been used for approximating key signatures of molecular quantum systems. Such approximations are for example the Wigner phase space method, the…

Numerical Analysis · Mathematics 2014-11-11 Wolfgang Gaim , Caroline Lasser

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

Poincare return maps are a fundamental tool for analyzing periodic orbits in hybrid dynamical systems, including legged locomotion, power electronics, and other cyber-physical systems with switching behavior. The Poincare return map…

Systems and Control · Electrical Eng. & Systems 2026-04-08 Varun Madabushi , Elizabeth Dietrich , Hanna Krasowski , Maegan Tucker

The article is devoted to the expansions of iterated Ito stochastic integrals based on generalized multiple Fourier series converging in the sense of norm in the space $L_2([t, T]^k),$ $k\in\mathbb{N}.$ The method of generalized multiple…

Probability · Mathematics 2026-02-10 Dmitriy F. Kuznetsov

We present iHOMER, an iterative version of the HOMER method to extract Lund fragmentation functions from experimental data. Through iterations, we address the information gap between latent and observable phase spaces and systematically…

A general technique for the periodic orbit quantization of systems with near-integrable to mixed regular-chaotic dynamics is introduced. A small set of periodic orbits is sufficient for the construction of the semiclassical recurrence…

chao-dyn · Physics 2009-10-31 J. Main , G. Wunner

Renormalized homotopy continuation on toric varieties is introduced as a tool for solving sparse systems of polynomial equations, or sparse systems of exponential sums. The cost of continuation depends on a renormalized condition length,…

Numerical Analysis · Mathematics 2025-06-23 Gregorio Malajovich

The flux reconstruction (FR) approach offers a flexible framework for describing a range of high-order numerical schemes; including nodal discontinuous Galerkin and spectral difference schemes. This is accomplished through the use of…

Numerical Analysis · Mathematics 2020-06-25 Will Trojak , Freddie Witherden

Classical chaotic systems with symbolic dynamics but strong pruning present a particular challenge for the application of semiclassical quantization methods. In the present study we show that the technique of periodic orbit quantization by…

Chaotic Dynamics · Physics 2007-05-23 K. Weibert , J. Main , G. Wunner

In this paper we study stochastic quasi-Newton methods for nonconvex stochastic optimization, where we assume that only stochastic information of the gradients of the objective function is available via a stochastic first-order oracle…

Optimization and Control · Mathematics 2014-12-05 Xiao Wang , Shiqian Ma , Wei Liu

In this paper we focus on the solution of shifted quasiseparable systems and of more general parameter dependent matrix equations with quasiseparable representations. We propose an efficient algorithm exploiting the invariance of the…

Numerical Analysis · Mathematics 2017-08-07 Paola Boito , Yuli Eidelman , Luca Gemignani

We provide a computationally and statistically efficient method for estimating the parameters of a stochastic covariance model observed on a regular spatial grid in any number of dimensions. Our proposed method, which we call the Debiased…

Methodology · Statistics 2022-04-27 Arthur P. Guillaumin , Adam M. Sykulski , Sofia C. Olhede , Frederik J. Simons

Matrix denoising is central to signal processing and machine learning. Its statistical analysis when the matrix to infer has a factorised structure with a rank growing proportionally to its dimension remains a challenge, except when it is…

Disordered Systems and Neural Networks · Physics 2025-03-17 Jean Barbier , Francesco Camilli , Justin Ko , Koki Okajima

In semiclassical theories for chaotic systems such as Gutzwiller's periodic orbit theory the energy eigenvalues and resonances are obtained as poles of a non-convergent series g(w)=sum_n A_n exp(i s_n w). We present a general method for the…

chao-dyn · Physics 2009-10-30 J. Main , V. A. Mandelshtam , G. Wunner , H. S. Taylor

The Hermite-Birkhoff interpolation problem of a function given on arbitrarily distributed points on the sphere and other manifolds is considered. Each proposed interpolant is expressed as a linear combination of basis functions, the…

Numerical Analysis · Mathematics 2017-05-03 Giampietro Allasia , Roberto Cavoretto , Alessandra De Rossi

This paper considers the problem of regression over distributions, which is becoming increasingly important in machine learning. Existing approaches often ignore the geometry of the probability space or are computationally expensive. To…

Machine Learning · Computer Science 2025-10-31 Maksim Maslov , Alexander Kugaevskikh , Matthew Ivanov

We consider the problem of determining the weights of a quantum ensemble. That is to say, given a quantum system that is in a set of possible known states according to an unknown probability law, we give strategies to estimate the…

Quantum Physics · Physics 2010-02-01 J. I. de Vicente , J. Calsamiglia , R. Munoz-Tapia , E. Bagan

Full waveform inversion (FWI) is a challenging, ill-posed nonlinear inverse problem that requires robust regularization techniques to stabilize the solution and yield geologically meaningful results, especially when dealing with sparse…

Numerical Analysis · Mathematics 2025-05-02 Ali Gholami , Silvia Gazzola