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This paper is concerned with the design and analysis of a fully adaptive eigenvalue solver for linear symmetric operators. After transforming the original problem into an equivalent one formulated on $\ell_2$, the space of square summable…

Numerical Analysis · Mathematics 2007-11-08 W. Dahmen , T. Rohwedder , R. Schneider , A. Zeiser

Given two real symmetric matrices, their eigenvalue configuration is the relative arrangement of their eigenvalues on the real line. In this paper, we consider the following problem: given two parametric real symmetric matrices and an…

Algebraic Geometry · Mathematics 2026-05-22 Hoon Hong , Daniel Profili , J. Rafael Sendra

We analyze an algorithm for computing a skew-Hermitian logarithm of a unitary matrix. This algorithm is very easy to implement using standard software and it works well even for unitary matrices with no spectral conditions assumed. Certain…

Numerical Analysis · Mathematics 2015-04-16 Terry A. Loring

This paper presents a parallel algorithm for finding the smallest eigenvalue of a particular form of ill-conditioned Hankel matrix, which requires the use of extremely high precision arithmetic. Surprisingly, we find that commonly-used…

Numerical Analysis · Mathematics 2009-02-06 Niall Emmart , Charles C. Weems , Yang Chen

Finding eigenvalue distributions for a number of sparse random matrix ensembles can be reduced to solving nonlinear integral equations of the Hammerstein type. While a systematic mathematical theory of such equations exists, it has not been…

Disordered Systems and Neural Networks · Physics 2025-01-24 Pawat Akara-pipattana , Oleg Evnin

We present a quantum algorithm for estimating the matrix determinant based on quantum spectral sampling. The algorithm estimates the logarithm of the determinant of an $n \times n$ positive sparse matrix to an accuracy $\epsilon$ in time…

Quantum Physics · Physics 2025-05-02 Vittorio Giovannetti , Seth Lloyd , Lorenzo Maccone

We present an iteration for the computation of simple eigenvalues using a pseudospectrum approach. The most appealing characteristic of the proposed iteration is that it reduces the computation of a single eigenvalue to a small number of…

Numerical Analysis · Mathematics 2007-05-23 Ioannis Koutis

Quantum subspace diagonalization methods are an exciting new class of algorithms for solving large\rev{-}scale eigenvalue problems using quantum computers. Unfortunately, these methods require the solution of an ill-conditioned generalized…

Quantum Physics · Physics 2023-06-16 Ethan N. Epperly , Lin Lin , Yuji Nakatsukasa

For a Hermitian matrix $H \in \mathbb C^{n,n}$ and symmetric matrices $S_0, S_1,\ldots,S_k \in \mathbb C^{n,n}$, we consider the problem of computing the supremum of $\left\{ \frac{v^*Hv}{v^*v}:~v\in \mathbb C^{n}\setminus…

Numerical Analysis · Mathematics 2021-06-28 Anshul Prajapati , Punit Sharma

In this paper we present an efficient algorithm to compute the eigen decomposition of a matrix that is a weighted sum of the self outer products of vectors such as a covariance matrix of data. A well known algorithm to compute the eigen…

Numerical Analysis · Computer Science 2017-06-08 Youhei Akimoto

The first step when solving an infinite-dimensional eigenvalue problem is often to discretize it. We show that one must be extremely careful when discretizing nonlinear eigenvalue problems. Using examples, we show that discretization can:…

Numerical Analysis · Mathematics 2023-05-04 Matthew J. Colbrook , Alex Townsend

Matrices with low-rank structure are ubiquitous in scientific computing. Choosing an appropriate rank is a key step in many computational algorithms that exploit low-rank structure. However, estimating the rank has been done largely in an…

Numerical Analysis · Mathematics 2024-01-08 Maike Meier , Yuji Nakatsukasa

Computing the eigenvectors and eigenvalues of a perturbed matrix can be remarkably difficult when the unperturbed matrix has repeated eigenvalues. In this work we show how the limiting eigenvectors and eigenvalues of a symmetric matrix…

Numerical Analysis · Mathematics 2025-07-08 Konstantin Usevich , Simon Barthelme

Estimating the eigenvalues of non-normal matrices is a foundational problem with far-reaching implications, from modeling non-Hermitian quantum systems to analyzing complex fluid dynamics. Yet, this task remains beyond the reach of standard…

Quantum Physics · Physics 2025-10-23 Yukun Zhang , Yusen Wu , Xiao Yuan

In this paper the author introduces a new domain decomposition method for the solution of discretised integral equation eigenvalue problems. The new domain decomposition method is motivated by the so-called automated multi-level…

Numerical Analysis · Mathematics 2017-12-29 Peter Gerds

The eigenvalue problem of the spherically symmetric oscillator Hamiltonian is revisited in the context of canonical raising and lowering operators. The Hamiltonian is then factorized in terms of two not mutually adjoint factorizing…

Quantum Physics · Physics 2009-02-26 Ivan Cabrera-Munguia , Oscar Rosas-Ortiz

The canonical quantum Hamiltonian eigenvalue problem for an anharmonic oscillator with a Lagrangian L = \dot{\phi}^2/2 - m^2 \phi^2/2 - g m^3 \phi^4 is numerically solved in two ways. One of the ways uses a plain cutoff on the number of…

Quantum Physics · Physics 2013-02-07 Krzysztof Piotr Wójcik

An operator analogue of the FEAST matrix eigensolver is developed to compute the discrete part of the spectrum of a differential operator in a region of interest in the complex plane. Unbounded search regions are handled with a novel…

Numerical Analysis · Mathematics 2024-11-15 Andrew Horning , Alex Townsend

A unified theory of orthogonal polynomials of a discrete variable is presented through the eigenvalue problem of hermitian matrices of finite or infinite dimensions. It can be considered as a matrix version of exactly solvable Schr\"odinger…

Classical Analysis and ODEs · Mathematics 2008-11-26 Satoru Odake , Ryu Sasaki

We develop spectral methods for ODEs and operator eigenvalue problems that are based on a least-squares formulation of the problem. The key tool is a method for rectangular generalized eigenvalue problems, which we extend to quasimatrices…

Numerical Analysis · Mathematics 2021-09-14 Behnam Hashemi , Yuji Nakatsukasa