English

A Note on the Stability of the Sherman-Morrison-Woodbury Formula

Numerical Analysis 2025-04-08 v1 Numerical Analysis

Abstract

We study the numerical stability of the Sherman-Morrison-Woodbury (SMW) identity. Let B=A+UVTB = A + UV^T and assume UU and VV both have full-column rank. We explore error bounds for the SMW identity when we are only able to compute approximate inverses. For both forward and backward errors, we present upper bounds as a function of the two-norm error of the approximate inverses. We verify with numerical experiments that, in certain cases, our bounds accurately capture the behavior of the errors.

Keywords

Cite

@article{arxiv.2504.04554,
  title  = {A Note on the Stability of the Sherman-Morrison-Woodbury Formula},
  author = {Linkai Ma and Christos Boutsikas and Mehrdad Ghadiri and Petros Drineas},
  journal= {arXiv preprint arXiv:2504.04554},
  year   = {2025}
}