Title
TWICE IS ENOUGH FOR DANGEROUS EIGENVALUES
Abstract
We analyze the stability of a class of eigensolvers that target interior eigenvalues with rational filters. We show that subspace iteration with a rational filter is robust even when an eigenvalue is near a filter's pole. These dangerous eigenvalues contribute to large round-off errors in the first iteration but are self-correcting in later iterations. For matrices with orthogonal eigenvectors (e.g., real-symmetric or complex Hermitian), two iterations are enough to reduce round-off errors to the order of the unit round-off. In contrast, Krylov methods accelerated by rational filters with fixed poles typically fail to converge to unit round-off accuracy when an eigenvalue is close to a pole. In the context of Arnoldi with shift-and-invert enhancement, we demonstrate a simple restart strategy that recovers full precision in the target eigenpairs.
Year
DOI
Venue
2022
10.1137/20M1385330
SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS
Keywords
DocType
Volume
subspace iteration, Arnoldi, shift-and-invert, rational filters, FEAST, CIRR
Journal
43
Issue
ISSN
Citations 
1
0895-4798
0
PageRank 
References 
Authors
0.34
0
2
Name
Order
Citations
PageRank
Andrew Horning110.71
Yuji Nakatsukasa29717.74