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In this paper we discuss a new approach to the quasinormal-mode problem in general relativity. By combining a characteristic formulation of the perturbation equations with the integration of a suitable phase-function for a complex valued…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Lars Samuelsson , Nils Andersson , Asimina Maniopoulou

In this note, we propose a symplectic algorithm for the stable manifolds of the Hamilton-Jacobi equations combined with an iterative procedure in [Sakamoto-van~der Schaft, IEEE Transactions on Automatic Control, 2008]. Our algorithm…

Optimization and Control · Mathematics 2021-08-16 Guoyuan Chen , Gaosheng Zhu

It is well known that general variational inequalities provide us with a unified, natural, novel and simple framework to study a wide class of unrelated problems, which arise in pure and applied sciences. In this paper, we present a number…

Optimization and Control · Mathematics 2020-09-24 M. A. Noor , K. I. Noor , M. Th. Rassias

Let $\{T^z\}$ be an ergodic action of the group $Z^n$ by automorphisms of the probability space $(X,m)$, $\sum_{i}^\infty a_i<\infty$, $a_i>0$. For any sequence $M_k\to +\infty$ there exist $N_k>M_k$ and a function $ f\in L_1(X,m)$ such…

Dynamical Systems · Mathematics 2025-07-23 Valery V. Ryzhikov

This work is an extended version of the paper arXiv:0803.2669v1[math-ph], in which the main results were announced. We consider certain classical diffusion process for a wave function on the phase space. It is shown that at the time of…

Mathematical Physics · Physics 2008-12-31 E. M. Beniaminov

In a real Hilbert space setting, we investigate the asymptotic behavior of the solutions of the classical Arrow-Hurwicz differential system combined with Tikhonov regularizing terms. Under some newly proposed conditions on the Tikhonov…

Optimization and Control · Mathematics 2025-09-03 Fouad Battahi , Zaki Chbani , Simon K. Niederländer , Hassan Riahi

We study the Hamilton-Jacobi formulation of effective mechanical actions associated with holographic renormalization group flows when the field theory is put on the sphere and mass terms are turned on. Although the system is supersymmetric…

High Energy Physics - Theory · Physics 2020-10-15 Nakwoo Kim , Se-Jin Kim

The variational formulation for Lie-transform Hamiltonian perturbation theory is presented in terms of an action functional defined on a two-dimensional parameter space. A fundamental equation in Hamiltonian perturbation theory is shown to…

Plasma Physics · Physics 2009-11-07 Alain J. Brizard

In statistical mechanics, computing the partition function is generally difficult. An approximation method using a variational autoregressive network (VAN) has been proposed recently. This approach offers the advantage of directly…

Disordered Systems and Neural Networks · Physics 2024-05-21 Yuta Tamura , Masayuki Ohzeki

The main purpose of this paper is to show the existence of action-angle variables for integrable Hamiltonian systems on Dirac manifolds under some natural regularity and compactness conditions, using the torus action approach. We show that…

Symplectic Geometry · Mathematics 2012-04-18 Nguyen Tien Zung

In this paper, we develop a systematical approach in applying an asymptotic method of moving planes to investigate qualitative properties of positive solutions for fractional parabolic equations. We first obtain a series of needed key…

Analysis of PDEs · Mathematics 2020-06-26 Wenxiong Chen , Pengyan Wang , Yahui Niu , Yunyun Hu

In this work, a kernel-based surrogate for integrating Hamiltonian dynamics that is symplectic by construction and tailored to large prediction horizons is proposed. The method learns a scalar potential whose gradient enters a…

Numerical Analysis · Mathematics 2026-01-27 Robin Herkert , Tobias Ehring , Bernard Haasdonk

The generalized pseudospectral method is employed for the accurate calculation of eigenvalues, densities and expectation values for the spiked harmonic oscillators. This allows \emph{nonuniform} and \emph{optimal} spatial discretization of…

Quantum Physics · Physics 2015-06-16 Amlan K. Roy

We investigate variational methods for finding approximate solutions to the Fokker-Planck equation, especially in cases lacking detailed balance. These schemes fall into two classes: those in which a Hermitian operator is constructed from…

Condensed Matter · Physics 2009-10-28 T. Blum , A. J. McKane

An invertible function is bi-Lipschitz if both the function and its inverse have bounded Lipschitz constants. Nowadays, most Normalizing Flows are bi-Lipschitz by design or by training to limit numerical errors (among other things). In this…

Machine Learning · Computer Science 2024-03-08 Alexandre Verine , Benjamin Negrevergne , Fabrice Rossi , Yann Chevaleyre

It is known that approximating the Regge-Wheeler Potential with step functions significantly modifies the Schwarzschild black hole quasinormal mode spectrum. Surprisingly, this change in the spectrum has little impact on the ringdown…

General Relativity and Quantum Cosmology · Physics 2020-05-06 Ramin G. Daghigh , Michael D. Green , Jodin C. Morey

We present a new numerical method to price vanilla options quickly in time-changed Brownian motion models. The method is based on rational function approximations of the Black-Scholes formula. Detailed numerical results are given for a…

Computational Finance · Quantitative Finance 2012-04-02 Martijn Pistorius , Johannes Stolte

We consider the question of how approximations satisfying Dirichlet's theorem spiral around vectors in $\mathbb{R}^d$. We give pointwise almost everywhere results (using only the Birkhoff ergodic theorem on the space of lattices). In…

Number Theory · Mathematics 2014-11-27 Jayadev S. Athreya , Anish Ghosh , Jimmy Tseng

We consider stochastic variational inequalities with monotone operators defined as the expected value of a random operator. We assume the feasible set is the intersection of a large family of convex sets. We propose a method that combines…

Optimization and Control · Mathematics 2017-03-03 Alfredo Iusem , Alejandro Jofré , Philip Thompson

Compact formulas for bounce and transit orbit averaging of the fluctuation-amplitude eikonal factor in axisymmetric tokamak geometry, which is frequently encountered in bounce-gyrokinetic description of microturbulence, are given in terms…

Plasma Physics · Physics 2015-06-22 F. -X. Duthoit , A. J. Brizard , T. S. Hahm