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Using analytical and numerical Evans-function techniques, we examine the spectral stability of strong-detonation-wave solutions of Majda's scalar model for a reacting gas mixture with an Arrhenius-type ignition function. We introduce an…

Analysis of PDEs · Mathematics 2017-06-09 Jeffrey Humpherys , Gregory Lyng , Kevin Zumbrun

The Hilbert-Chapman-Enskog expansion of the kinetic equations in mean flight times is believed to be asymptotic rather than convergent. It is therefore inadvisable to use lower order results to simplify the current approximation as is done…

Fluid Dynamics · Physics 2009-11-10 Edward A. Spiegel , Jean-Luc Thiffeault

In this paper, we complement recent results of Bronski and Johnson and of Johnson and Zumbrun concerning the modulational stability of spatially periodic traveling wave solutions of the generalized Korteweg-de Vries equation. In this…

Analysis of PDEs · Mathematics 2015-05-18 Mathew A. Johnson , Kevin Zumbrun , Jared C. Bronski

The Evans function is a powerful tool for the stability analysis of viscous shock profiles; zeros of this function carry stability information. In the one-dimensional case, it is typical to compute the Evans function using Goodman's…

Analysis of PDEs · Mathematics 2017-03-08 Blake Barker , Jeffrey Humpherys , Gregory Lyng , Kevin Zumbrun

The nonlinear Schr\"{o}dinger equation with a linear periodic potential and a nonlinearity coefficient $\Gamma$ with a discontinuity supports stationary localized solitary waves with frequencies inside spectral gaps, so called surface gap…

Pattern Formation and Solitons · Physics 2011-03-01 Elizabeth Blank , Tomáš Dohnal

In Evans function computations of the spectra of asymptotically constant-coefficient linear operators, a basic issue is the efficient and numerically stable computation of subspaces evolving according to the associated eigenvalue ODE. For…

Numerical Analysis · Mathematics 2017-06-12 Jeffrey Humpherys , Kevin Zumbrun

We examine the spectral stability of travelling waves of the haptotaxis model studied in Harley et al (2014a). In the process we apply Li\'enard coordinates to the linearised stability problem and use a Riccati-transform/Grassmanian…

Dynamical Systems · Mathematics 2020-06-01 K. E. Harley , P. van Heijster , R. Marangell , G. J. Pettet , T. V. Roberts , M. Wechselberger

It is well known that for gradient systems in Euclidean space or on a Riemannian manifold, the energy decreases monotonically along solutions. In this letter we derive and analyse functionally fitted energy-diminishing methods to preserve…

Numerical Analysis · Mathematics 2018-04-17 Bin Wang , Ting Li , Yajun Wu

We carry out a systematic analytical and numerical study of spectral stability of discontinuous roll wave solutions of the inviscid Saint Venant equations, based on a periodic Evans-Lopatinski determinant analogous to the periodic Evans…

Analysis of PDEs · Mathematics 2018-11-14 Mathew A. Johnson , Pascal Noble , L. Miguel Rodrigues , Zhao Yang , Kevin Zumbrun

We study the problem of numerical differentiation of functions from weighted Wiener classes. We construct and analyze a truncation Legendre method to recover arbitrary order derivatives. The main focus is on obtaining error estimates in…

Numerical Analysis · Mathematics 2025-06-16 Maksym Kyselov

As second-order methods, Gauss--Newton-type methods can be more effective than first-order methods for the solution of nonsmooth optimization problems with expensive-to-evaluate smooth components. Such methods, however, often do not…

Optimization and Control · Mathematics 2020-09-01 Jyrki Jauhiainen , Petri Kuusela , Aku Seppänen , Tuomo Valkonen

This paper presents an Euler--Lagrange system for a continuous-time model of the accelerated gradient methods in smooth convex optimization and proposes an associated Lyapunov-function-based convergence analysis framework. Recently,…

Optimization and Control · Mathematics 2024-04-05 Mitsuru Toyoda , Akatsuki Nishioka , Mirai Tanaka

We introduce an arbitrary order, stabilized finite element method for solving a unique continuation problem subject to the time-harmonic elastic wave equation with variable coefficients. Based on conditional stability estimates we prove…

Numerical Analysis · Mathematics 2023-04-25 Erik Burman , Janosch Preuss

Here we develop an option pricing method based on Legendre series expansion of the density function. The key insight, relying on the close relation of the characteristic function with the series coefficients, allows to recover the density…

Mathematical Finance · Quantitative Finance 2017-03-21 Julien Hok , Tat Lung Chan

This work presents a technique for statistically modeling errors introduced by reduced-order models. The method employs Gaussian-process regression to construct a mapping from a small number of computationally inexpensive `error indicators'…

Numerical Analysis · Computer Science 2015-04-16 Martin Drohmann , Kevin Carlberg

Using the relation established by Johnson--Zumbrun between Hill's method of aproximating spectra of periodic-coefficient ordinary differential operators and a generalized periodic Evans function given by the $2$-modified characteristic…

Spectral Theory · Mathematics 2010-11-29 Kevin Zumbrun

We present a new numerical method for computing the pure-point spectrum associated with the linear stability of coherent structures. In the context of the Evans function shooting and matching approach, all the relevant information is…

Numerical Analysis · Mathematics 2009-07-06 Veerle Ledoux , Simon J. A. Malham , Vera Thummler

Current spectral simulations of Einstein's equations require writing the equations in first-order form, potentially introducing instabilities and inefficiencies. We present a new penalty method for pseudo-spectral evolutions of second order…

General Relativity and Quantum Cosmology · Physics 2014-11-21 Nicholas W. Taylor , Lawrence E. Kidder , Saul A. Teukolsky

The numerical evaluation of statistics plays a crucial role in statistical physics and its applied fields. It is possible to evaluate the statistics for a stochastic differential equation with Gaussian white noise via the corresponding…

Numerical Analysis · Mathematics 2023-07-04 Jun Ohkubo

We study the stability/instability of the subsonic travelling waves of the Nonlinear Schr\"odinger Equation in dimension one. Our aim is to propose several methods for showing instability (use of the Grillakis-Shatah-Strauss theory, proof…

Analysis of PDEs · Mathematics 2016-01-20 David Chiron