1 citations · 1 across the 8 of their papers we have counts for
8 papers
Sketch-and-Restart: Randomized Sketching in Quadrature-Based Restarting for Matrix Functions
Stefan Güttel, Jingyu Liu, Lauri Nyman
We develop a sketch-and-restart framework for computing the action of a matrix function on a vector, , where is large, sparse, and non-Hermitian. The framework combines…
Flexible GMRES converges in two phases
Stefan Güttel, Lauri Nyman
We derive a sharp upper bound on the residuals produced by the flexible GMRES (FGMRES) method. The bound shows that FGMRES exhibits two phases of convergence depending on the resid…
Singular vector spaces for computing the structured distance to singularity
Lauri Nyman
Finding the distance to singularity for a matrix is a ubiquitous problem in numerical linear algebra, and is elegantly solved by the Eckart-Young-Mirsky theorem. Its structured var…
Nearest matrix with multiple eigenvalues by Riemannian optimization
Vanni Noferini, Lauri Nyman, Federico Poloni
Given a square complex matrix , we tackle the problem of finding the nearest matrix with multiple eigenvalues or, equivalently when had distinct eigenvalues, the nearest def…
Finding the nearest -stable pencil with Riemannian optimization
Vanni Noferini, Lauri Nyman
This paper considers the problem of finding the nearest -stable pencil to a given square pencil , where a pencil is called -stable if it is…
Riemann-Oracle: A general-purpose Riemannian optimizer to solve nearness problems in matrix theory
Miryam Gnazzo, Vanni Noferini, Lauri Nyman +1
We propose an extremely versatile approach to address a large family of matrix nearness problems, possibly with additional linear constraints. Our method is based on splitting a ma…
A Riemannian optimization method to compute the nearest singular pencil
Froilán Dopico, Vanni Noferini, Lauri Nyman
Given a square pencil , where and are complex (resp. real) matrices, we consider the problem of finding the singular complex (resp. real) pencil nearest…
Perturbation theory of transfer function matrices
Vanni Noferini, Lauri Nyman, Javier Pérez +1
Zeros of rational transfer function matrices are the eigenvalues of associated polynomial system matrices , under minimality conditions. In this paper we define a stru…