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Partition functions of probability distributions are important quantities for model evaluation and comparisons. We present a new method to compute partition functions of complex and multimodal distributions. Such distributions are often…

Machine Learning · Statistics 2016-05-27 David Carlson , Patrick Stinson , Ari Pakman , Liam Paninski

We develop a spectrally accurate numerical method to compute solutions of a model partial differential equation used in plasma physics to describe diffusion in velocity space due to Fokker-Planck collisions. The solution is represented as a…

Classical Analysis and ODEs · Mathematics 2015-03-18 Jon Wilkening , Antoine Cerfon

The long-standing paradox of the linear polarization signal of the Na i D1 line was recently resolved by accounting for the atom's hyperfine structure and the detailed spectral structure of the incident radiation field. That modeling relied…

Solar and Stellar Astrophysics · Physics 2023-09-25 Gioele Janett , Ernest Alsina Ballester , Luca Belluzzi , Tanausú del Pino Alemán , Javier Trujillo Bueno

Angle-frequency coupling in scattering of polarized light on atoms is represented by the angle-dependent (AD) partial frequency redistribution (PRD) matrices. There are several lines in the linearly polarized solar spectrum, for which PRD…

Solar and Stellar Astrophysics · Physics 2020-07-29 K. N. Nagendra , K. Sowmya , M. Sampoorna , J. O. Stenflo , L. S. Anusha

Polarimetry is extensively used as a tool to trace the interstellar magnetic field projected on the plane of sky. Moreover, it is also possible to estimate the magnetic field intensity from polarimetric maps based on the Chandrasekhar-Fermi…

Astrophysics · Physics 2009-11-13 D. Falceta-Goncalves , A. Lazarian , G. Kowal

We present the frequency redistribution function for the polarized three-term atom of the $\Lambda$-type in the collisionless regime, and we specialize it to the case where both the initial and final terms of the three-state transition are…

Astrophysics of Galaxies · Physics 2016-12-21 R. Casini , R. Manso Sainz

In this work we propose an efficient and accurate multi-scale optical simulation algorithm by applying a numerical version of slowly varying envelope approximation in FEM. Specifically, we employ the fast iterative method to quickly compute…

Optics · Physics 2024-12-03 Fan Xiao , Jingwei Wang , Zhongfei Xiong , Yuntian Chen

We derive closed-form expressions for the poles and zeros of approximate fractional integrator/differentiator filters, which correspond to spectral roll-off filters having any desired log-log slope to a controllable degree of accuracy over…

Computational Engineering, Finance, and Science · Computer Science 2016-06-21 Julius Orion Smith , Harrison Freeman Smith

Compressive covariance estimation has arisen as a class of techniques whose aim is to obtain second-order statistics of stochastic processes from compressive measurements. Recently, these methods have been used in various image processing…

Image and Video Processing · Electrical Eng. & Systems 2022-07-27 Jonathan Monsalve , Juan Ramirez , Iñaki Esnaola , Henry Arguello

Unions of graph multiplier operators are an important class of linear operators for processing signals defined on graphs. We present a novel method to efficiently distribute the application of these operators. The proposed method features…

Distributed, Parallel, and Cluster Computing · Computer Science 2017-08-01 David I Shuman , Pierre Vandergheynst , Daniel Kressner , Pascal Frossard

In many applications and physical phenomena, bivariate signals are polarized, i.e. they trace an elliptical trajectory over time when viewed in the 2D planes of their two components. The smooth evolution of this elliptical trajectory,…

Signal Processing · Electrical Eng. & Systems 2025-06-26 Yusuf Yigit Pilavci , Pierre Palud , Julien Flamant , Pierre-Antoine Thouvenin , Jérémie Boulanger , Pierre Chainais

Classical approximation bases such as Chebyshev polynomials provide principled and interpretable representations, but their multivariate tensor-product constructions scale exponentially with dimension and impose axis-aligned structure that…

Machine Learning · Computer Science 2026-04-07 Milo Coombs

Context. The numerical modeling of the generation and transfer of polarized radiation is a key task in solar and stellar physics research and has led to a relevant class of discrete problems that can be reframed as linear systems. In order…

Solar and Stellar Astrophysics · Physics 2021-12-08 Gioele Janett , Pietro Benedusi , Luca Belluzzi , Rolf Krause

We present two new accurate and efficient method to compute the formal solution of the polarized radiative transfer equation. In this work, the source function and the absorption matrix are approximated using quadratic and cubic Bezier…

Solar and Stellar Astrophysics · Physics 2015-06-12 J. de la Cruz Rodríguez , N. Piskunov

For a function that is analytic on and around an interval, Chebyshev polynomial interpolation provides spectral convergence. However, if the function has a singularity close to the interval, the rate of convergence is near one. In these…

Numerical Analysis · Mathematics 2017-08-10 Kevin W. Aiton , Tobin A. Driscoll

With the forthcoming release of high precision polarization measurements, such as from the Planck satellite, it becomes critical to evaluate the performance of estimators for the polarization fraction and angle. These two physical…

Instrumentation and Methods for Astrophysics · Physics 2015-02-11 L. Montier , S. Plaszczynski , F. Levrier , M. Tristram , D. Alina , I. Ristorcelli , J. -P. Bernard , V. Guillet

The problem of radio wave reflection from an optically thick plane monotonous layer of magnetized plasma is considered at present work. The plasma electron density irregularities are described by spatial spectrum of an arbitrary form. The…

Plasma Physics · Physics 2009-09-25 N. A. Zabotin , A. G. Bronin

A method based on the Fast Fourier Transform is proposed to obtain the dispersion relation of acoustic waves in heterogeneous periodic media with arbitrary microstructures. The microstructure is explicitly considered using a voxelized…

Materials Science · Physics 2021-06-24 J. Segurado , R. A. Lebensohn

The common approach to radial distortion is by the means of polynomial approximation, which introduces distortion-specific parameters into the camera model and requires estimation of these distortion parameters. The task of estimating…

Computer Vision and Pattern Recognition · Computer Science 2007-05-23 Lili Ma , YangQuan Chen , Kevin L. Moore

In this paper, we introduce a method known as polynomial frame approximation for approximating smooth, multivariate functions defined on irregular domains in $d$ dimensions, where $d$ can be arbitrary. This method is simple, and relies only…

Numerical Analysis · Mathematics 2020-05-27 Ben Adcock , Daan Huybrechs