27th Conference of the International Linear Algebra Society (ILAS 2026)

Least-squares Rational Approximation Using Riemannian Optimization

May 19, 2026, 11:00 AM

25m

Torgersen Hall 1020 (Virginia Tech)

Minisymposium Talk Numerical Linear Algebra Tools for Model Order Reduction Numerical Linear Algebra Tools for Model Order Reduction

Speaker

Petar Mlinarić (University of Zagreb)

Description

Vector fitting is a widely used method for least-squares rational approximation that approaches the nonlinear least-squares problem with a sequence of linear least-squares problems. By contrast, the iterative rational Krylov algorithm (IRKA) is a method for a continuous least-squares approximation, originally formulated as a fixed-point iteration and with a recent interpretation as a Riemannian optimization method. In this talk, we discuss the application of Riemannian optimization techniques to the (discrete) least-squares rational approximation problem and compare them with vector fitting.