Structure preserving quaternion conjugate gradient-type methods for solving non-Hermitian quaternion linear systems

Fuente: arXiv
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Main Authors: Huang, Baohua, Li, Tao, Li, Wen
Format: Preprint
Published: 2026
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author Huang, Baohua
Li, Tao
Li, Wen
author_facet Huang, Baohua
Li, Tao
Li, Wen
contents In this paper, we consider the non-Hermitian quaternion linear systems arising from color image restoration and three-dimensional signal filtering problems. For exploring to solve such systems, we present two innovative structure-preserving conjugate gradient-type methods, QNHERLQ and QNHERQR, which are based on the unitary equivalence transformations of the non-Hermitian quaternion matrices to tridiagonal forms, called quaternion Saunders-Simon-Yip tridiagonalization procedure. The proposed tridiagonalization procedure for non-Hermitian quaternion matrices is closely related to the quaternion Lanczos process for Hermitian matrices, and is very different from the quaternion Lanczos biorthogonalization process for non-Hermitian matrices. The convergence of QNHERLQ and QNHERQR is discussed, which depends on the singular values of the coefficient matrix. Also we show that both algorithms have the finite termination property and constant costs per iteration step. Numerical results illustrate that the proposed algorithms are with the robustness and effectiveness compared with QGMRES and QQMR.
format Preprint
id arxiv_https___arxiv_org_abs_2605_17732
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Structure preserving quaternion conjugate gradient-type methods for solving non-Hermitian quaternion linear systems
Huang, Baohua
Li, Tao
Li, Wen
Numerical Analysis
15B33, 65F10, 94A08
In this paper, we consider the non-Hermitian quaternion linear systems arising from color image restoration and three-dimensional signal filtering problems. For exploring to solve such systems, we present two innovative structure-preserving conjugate gradient-type methods, QNHERLQ and QNHERQR, which are based on the unitary equivalence transformations of the non-Hermitian quaternion matrices to tridiagonal forms, called quaternion Saunders-Simon-Yip tridiagonalization procedure. The proposed tridiagonalization procedure for non-Hermitian quaternion matrices is closely related to the quaternion Lanczos process for Hermitian matrices, and is very different from the quaternion Lanczos biorthogonalization process for non-Hermitian matrices. The convergence of QNHERLQ and QNHERQR is discussed, which depends on the singular values of the coefficient matrix. Also we show that both algorithms have the finite termination property and constant costs per iteration step. Numerical results illustrate that the proposed algorithms are with the robustness and effectiveness compared with QGMRES and QQMR.
title Structure preserving quaternion conjugate gradient-type methods for solving non-Hermitian quaternion linear systems
topic Numerical Analysis
15B33, 65F10, 94A08
url https://arxiv.org/abs/2605.17732