Certified Real Eigenvalue Location
Baran Solmaz, Tulay Ayyildiz
TL;DR
The paper introduces a certified real eigenvalue localization framework that combines Hermite-matrix based real-root certification with Gershgorin disk localization, anchored by La Budde's stable polynomial computation. By constructing univariate Hermite matrices $H_q(p)$ directly from polynomial coefficients and leveraging signature tests, the method certifies the presence or absence of real eigenvalues within Gershgorin disks and refined intervals via a bisection-like process. Key contributions include a rigorous Hermite–Gershgorin hybrid algorithm, a cost-conscious implementation with $O(n^3)$ upfront work, and demonstrated certified isolation on a concrete $5\times5$ example, with Julia implementation available online. This approach provides rigorous guarantees for real eigenvalue locations, offering a valuable tool for stability and resonance analyses where numerical solvers alone cannot certify reality of eigenvalues.
Abstract
The location of real eigenvalues provides critical insights into the stability and resonance properties of physical systems. This paper presents a hybrid symbolic numeric approach for certified real eigenvalue localization. Our method combines Gershgorin disk analysis with Hermite matrix certification to compute certified intervals that enclose the real eigenvalues. These intervals can be further refined through bisectionlike procedures to achieve the desired precision. The proposed approach delivers reliable interval certifications while preserving computational efficiency. The effectiveness of the framework is demonstrated through a concise, fully worked computational example.
