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In this article, we introduce a kind of numerical schemes, based on Pad$\acute{e}$ approximation, for two stochastic Hamiltonian systems which are treated separately. For the linear stochastic Hamiltonian systems, it is shown that the…

Numerical Analysis · Mathematics 2015-12-15 Liying Sun , Lijin Wang

It is shown how piecewise differentiable functions $F: \mathbb R^n \mapsto \mathbb R^m $ that are defined by evaluation programs can be approximated locally by a piecewise linear model based on a pair of sample points $\check x$ and $\hat…

Numerical Analysis · Mathematics 2017-08-14 Andreas Griewank , Tom Streubel , Lutz Lehmann , Manuel Radons , Richard Hasenfelder

The Fredholm-Hammerstein integral equations (FHIEs) with weakly singular kernels exhibit multi-point singularity at the endpoints or boundaries. The dense discretized matrices result in high computational complexity when employing numerical…

Numerical Analysis · Mathematics 2024-10-31 Min Wang , Zhimin Zhang

As is well known, in mathematics, any function could be approximated by the Pad\'e approximant. The Pad\'e approximant is the best approximation of a function by a rational function of given order. In fact, the Pad\'e approximant often…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-05 Hao Wei , Xiao-Peng Yan , Ya-Nan Zhou

Polynomials $Q_n(z)$, $n=0,1,\ldots,$ that are multi-orthogonal with respect to a Nikishin system of $p\geq 1$ compactly supported measures over the star-like set of $p+1$ rays $S_+:=\{z\in \mathbb{C}: z^{p+1}\geq 0 \}$ are investigated. We…

Classical Analysis and ODEs · Mathematics 2019-10-16 Abey López-García , Erwin Miña-Díaz

We introduce meromorphic nearby cycle functors and study their functorial properties. Moreover we apply them to monodromies of meromorphic functions in various situations. Combinatorial descriptions of their reduced Hodge spectra and Jordan…

Algebraic Geometry · Mathematics 2022-04-20 Tat Thang Nguyen , Kiyoshi Takeuchi

We present a systematic and reliable methodology, termed hierarchical mean-field theory (HMFT), to study and predict the behavior of strongly coupled many-particle systems. HMFT is a simple approximation, based upon group theoretical…

Strongly Correlated Electrons · Physics 2007-05-23 Gerardo Ortiz , Cristian D. Batista

We consider a framework for the construction of iterative schemes for operator equations that combine low-rank approximation in tensor formats and adaptive approximation in a basis. Under fairly general assumptions, we obtain a rigorous…

Numerical Analysis · Mathematics 2014-03-17 Markus Bachmayr , Wolfgang Dahmen

In (Commun Pure Appl Math 2(4):331-407, 1949), Grad proposed a Hermite series expansion for approximating solutions to kinetic equations that have an unbounded velocity space. However, for initial boundary value problems, poorly imposed…

Numerical Analysis · Mathematics 2023-03-01 Neeraj Sarna , Jan Giesselmann , Manuel Torrilhon

In this paper we continue the investigations initiated in \cite{LopLopstar} on ratio asymptotics of multiple orthogonal polynomials and functions of the second kind associated with Nikishin systems on star-like sets. We describe in detail…

Classical Analysis and ODEs · Mathematics 2023-08-30 Abey López-García , Guillermo López Lagomasino

The accuracy and effectiveness of Hermite spectral methods for the numerical discretization of partial differential equations on unbounded domains, are strongly affected by the amplitude of the Gaussian weight function employed to describe…

Numerical Analysis · Mathematics 2021-04-07 Lorella Fatone , Daniele Funaro , Gianmarco Manzini

Numerical integration methods are central to the study of self-gravitating systems, particularly those comprised of many bodies or otherwise beyond the reach of analytical methods. Predictor-corrector schemes, both multi-step methods and…

Instrumentation and Methods for Astrophysics · Physics 2025-01-24 Alexander J. Dittmann

Hermite processes are a class of self-similar processes with stationary increments. They often arise in limit theorems under long-range dependence. We derive new representations of Hermite processes with multiple Wiener-It\^o integrals,…

Probability · Mathematics 2020-05-11 Shuyang Bai

We shall consider a result of Fel'dman, where a sharp Baker-type lower bound is obtained for linear forms in the values of some E-functions. Fel'dman's proof is based on an explicit construction of Pad\'e approximations of the first kind…

Number Theory · Mathematics 2017-04-07 Keijo Väänänen

We study the logarithmic and ratio asymptotic of linear forms constructed from a Nikishin system which satisfy orthogonality conditions with respect to a system of measures generated from another Nikishin system. This construction combines…

Complex Variables · Mathematics 2019-10-22 U. Fidalgo Prieto , A. López García , G. López Lagomasino , V. N. Sorokin

In this work we discuss the problem of selecting suitable approximators from families of parameterized elementary functions that are known to be dense in a Hilbert space of functions. We consider and analyze published procedures, both…

Numerical Analysis · Computer Science 2016-09-01 Alexander N. Gorban , Ivan Yu. Tyukin , Danil V. Prokhorov , Konstantin I. Sofeikov

We present certain norm-compatible systems in $K_2$ of function fields of some CM elliptic curves. We demonstrate that these systems have some properties similar to elliptic units.

Algebraic Geometry · Mathematics 2007-05-23 Kenichiro Kimura

Motivated by classification, up to order isomorphism, of some dense subgroups of Euclidean space that are free of minimal rank, we obtain apparently new invariants for an equivalence relation (intermediate between Hermite and Smith) on…

Commutative Algebra · Mathematics 2017-03-14 David Handelman

We show that for finite dimensional regular Noetherian rings that contain a field or are smooth over a Dedekind domain, the comparison map from the Hermitian K-theory of genuine symmetric forms to that of symmetric forms is an equivalence…

K-Theory and Homology · Mathematics 2025-06-23 Marco Schlichting

In many ways the solution to the Hedin equations represents an exact solution to the many body problem. However, for most systems of practical interest, the solution to the Hedin equations is rendered nearly numerically intractable because…

Strongly Correlated Electrons · Physics 2026-03-19 Garry Goldstein