7 papers · 1 filter
Randomized Flexible LSQR and LSMR with applications to inverse problems
Alberto Bucci, Silvia Gazzola, Leonardo Robol
LSQR and LSMR are iterative methods, based on the Golub-Kahan bidiagonalization algorithm, widely used for large-scale linear least squares problems. FLSQR and FLSMR are flexible v…
Error formulas for block rational Krylov approximations of matrix functions
Stefano Massei, Leonardo Robol
This paper investigates explicit expressions for the error associated with the block rational Krylov approximation of matrix functions. Two formulas are proposed, both derived from…
Backward errors for multiple eigenpairs in structured and unstructured nonlinear eigenvalue problems
Miryam Gnazzo, Leonardo Robol
Given a nonlinear matrix-valued function and approximate eigenpairs , we discuss how to determine the smallest perturbation such that $[F + δF](λ_i) v_…
Preconditioned Low-Rank Riemannian Optimization for Symmetric Positive Definite Linear Matrix Equations
Ivan Bioli, Daniel Kressner, Leonardo Robol
This work is concerned with the numerical solution of large-scale symmetric positive definite matrix equations of the form $A_1XB_1^\top + A_2XB_2^\top + \dots + A_\ell X B_\ell^\t…
Randomized sketched TT-GMRES for linear systems with tensor structure
Alberto Bucci, Davide Palitta, Leonardo Robol
In the last decade, tensors have shown their potential as valuable tools for various tasks in numerical linear algebra. While most of the research has been focusing on how to compr…
Tropical Laurent series, their tropical roots, and localization results for the eigenvalues of nonlinear matrix functions
Gian Maria Negri Porzio, Vanni Noferini, Leonardo Robol
Tropical roots of tropical polynomials have been previously studied and used to localize roots of classical polynomials and eigenvalues of matrix polynomials. We extend the theory…