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In this paper, we compare two optimization algorithms using full Hessian and approximation Hessian to obtain numerical spherical designs through their variational characterization. Based on the obtained spherical design point sets, we…

Numerical Analysis · Mathematics 2024-01-03 Yuchen Xiao , Xiaosheng Zhuang

Forecast verification plays a crucial role in the development cycle of operational numerical weather prediction models. At the same time, verification remains a challenge as the traditionally used non-spatial forecast quality metrics…

Atmospheric and Oceanic Physics · Physics 2026-05-25 Gregor Skok , Katarina Kosovelj

We study an estimator for smoothing irregularly sampled data into a smooth map. The estimator has been widely used in astronomy, owing to its low level of noise; it involves a weight function -- or smoothing kernel -- w(\theta). We show…

Astrophysics · Physics 2009-11-06 Marco Lombardi , Peter Schneider

Removing the aberrations introduced by the Point Spread Function (PSF) is a fundamental aspect of astronomical image processing. The presence of noise in observed images makes deconvolution a nontrivial task that necessitates the use of…

Instrumentation and Methods for Astrophysics · Physics 2017-05-03 Samuel Farrens , Jean-Luc Starck , Fred Maurice Ngolè Mboula

We present a versatile formulation of the convolution operation that we term a "mapped convolution." The standard convolution operation implicitly samples the pixel grid and computes a weighted sum. Our mapped convolution decouples these…

Computer Vision and Pattern Recognition · Computer Science 2019-06-27 Marc Eder , True Price , Thanh Vu , Akash Bapat , Jan-Michael Frahm

We study the problem of deconvolution for light-sheet microscopy, where the data is corrupted by spatially varying blur and a combination of Poisson and Gaussian noise. The spatial variation of the point spread function (PSF) of a…

Obtaining constraints from the largest scales of a galaxy survey is challenging due to the survey mask allowing only partial measurement of large angular modes. This scatters information from the harmonic-space 2-point function away from…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-16 Henry S. Grasshorn Gebhardt , Olivier Doré

An important application of next-generation wide-field radio interferometers is making high dynamic range maps of radio emission. Traditional deconvolution methods like CLEAN can give poor recovery of diffuse structure, prompting the…

Instrumentation and Methods for Astrophysics · Physics 2024-10-23 Katrine A. Glasscock , Philip Bull , Jacob Burba , Hugh Garsden , Michael J. Wilensky

This paper introduces a general method to approximate the convolution of an arbitrary program with a Gaussian kernel. This process has the effect of smoothing out a program. Our compiler framework models intermediate values in the program…

Graphics · Computer Science 2017-06-06 Yuting Yang , Connelly Barnes

A collection of algorithms is described for numerically computing with smooth functions defined on the unit sphere. Functions are approximated to essentially machine precision by using a structure-preserving iterative variant of Gaussian…

Numerical Analysis · Mathematics 2016-04-05 Alex Townsend , Heather Wilber , Grady B. Wright

In this manuscript, we study the nearly flat approximation of a conformally invariant gravitational theory in metric measure space (MMS). In addition, we investigate the transformation of the energy-momentum tensor in this context and…

General Relativity and Quantum Cosmology · Physics 2023-02-28 Samaneh Oghbaiee , Nafiseh Rahmanpour , Hossein Shojaie

A new technique is presented for producing images from interferometric data. The method, ``smear fitting'', makes the constraints necessary for interferometric imaging double as a model, with uncertainties, of the sky brightness…

Astrophysics · Physics 2009-11-11 Robert I. Reid

It has been shown that the large--scale correlation functions of the density field (and velocity divergence field) follow a specific hierarchy in the quasilinear regime and for Gaussian initial conditions (Bernardeau 1992). The exact…

Astrophysics · Physics 2007-05-23 F. Bernardeau

In this work we introduced a new proposal to study the gravitational lensing theory by spherical lenses, starting from its surface mass density $\Sigma(x)$ written in terms of a decreasing function $f$ of a dimensionless coordinate $x$ on…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-21 Roger Hurtado , Leonardo Castaneda , Juan M. Tejeiro

The estimation of potential fields such as the gravitational or magnetic potential at the surface of a spherical planet from noisy observations taken at an altitude over an incomplete portion of the globe is a classic example of an…

Statistics Theory · Mathematics 2009-11-11 Frederik J Simons , F. A. Dahlen

Convergence maps of the integrated matter distribution are a key science result from weak gravitational lensing surveys. To date, recovering convergence maps has been performed using a planar approximation of the celestial sphere. However,…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-16 Christopher G. R. Wallis , Matthew A. Price , Jason D. McEwen , Thomas D. Kitching , Boris Leistedt , Antoine Plouviez

In this article, we show that (i) any smooth function on compact Riemann surface with non-empty smooth boundary $ (M, \partial M, g) $ can be realized as a Gaussian curvature function; (ii) any smooth function on $ \partial M $ can be…

Analysis of PDEs · Mathematics 2023-04-11 Jie Xu

We prove Richberg type theorem for $m$-subharmonic function. The main tool is the complex Hessian equation for which we obtain the existence of the unique smooth solution in strictly pseudoconvex domains.

Complex Variables · Mathematics 2014-04-24 Szymon Pliś

A new method for improving the resolution of astronomical images is presented. It is based on the principle that sampled data cannot be fully deconvolved without violating the sampling theorem. Thus, the sampled image should not be…

Astrophysics · Physics 2009-10-30 P. Magain , F. Courbin , S. Sohy

We describe a fast and accurate method to perform the convolution of a sky map with a general asymmetric main beam along any given scanning strategy. The method is based on the decomposition of the beam as a sum of circular functions, here…

Astrophysics · Physics 2009-11-10 M. Tristram , J. -C. Hamilton , J. F. Macias-Perez , C. Renault
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