An incomplete generalized minimum backward perturbation algorithm for large nonsymmetric linear systems  

作　　者：Lei SUN 

机构地区：[1]Jincheng College,Nanjing University of Aeronautics and Astronautics,Nanjing 210012,China

出　　处：《Frontiers of Mathematics in China》2023年第3期203-222,共20页中国高等学校学术文摘·数学（英文）

摘　　要：This paper gives the truncated version of the generalized minimum backward error algorithm(GMBACK)—the incomplete generalized minimum backward perturbation algorithm(IGMBACK)for large nonsymmetric linear systems.It is based on an incomplete orthogonalization of the Krylov vectors in question,and gives an approximate or quasi-minimum backward perturbation solution over the Krylov subspace.Theoretical properties of IGMBACK including finite termination,existence and uniqueness are discussed in details,and practical implementation issues associated with the IGMBACK algorithm are considered.Numerical experiments show that,the IGMBACK method is usually more efficient than GMBACK and GMRES,and IMBACK,GMBACK often have better convergence performance than GMRES.Specially,for sensitive matrices and right-hand sides being parallel to the left singular vectors corresponding to the smallest singular values of the coefficient matrices,GMRES does not necessarily converge,and IGMBACK,GMBACK usually converge and outperform GMRES.

关 键 词：Nonsymmetric linear systems Krylov subspace methods minimum backward perturbation incomplete orthogonalization process GMBACK GMRES 

分 类 号：O17[理学—数学]