导 师: 黎稳
学科专业: 070102
授予学位: 硕士
作 者: ;
机构地区: 华南师范大学
摘 要: 本文首先讨论了特征值与奇异值的Rayleigh商,考虑了Li/[15/]的反问题:设矩阵A的特征值为λ/_1≥λ/_2≥…≥λ/_n,对应的特征向量为u/_1,u/_2,…,u/_n,令U/_k=/(u/_1,u/_2,…,u/_k/),/(?/)/_k∈C~/(n×k/),/(?/)/_k~*/(?/)/_k=I/_/(k,ε/)≥0,如果‖sin/(?/)/(U/_k,/(?/)/_k/)‖=O/(ε/),那么trace/(/(?/)/_k~*A/(?/)/_k/)≥λ/_1+λ/_2+…+λ/_k+O/(ε~2/)。进一步将结论推广到任意矩阵的奇异值。其次讨论了用Rayleigh商来界定特征子空间的扰动界限,并改进了sun/[9/]的相应结论。 Firstly, we consider the Rayleigh quotient of the eigenvalues and singularvalues. On the one hand,we consider the converse of the result: Assume that n×nmatrix A is Hermitian with eigenvaluesλ/_1≥λ/_2≥…≥λ/_n, and correspondingorthogonal eigenvectors u/_1,u/_2,…,u/_n. Let U/_k=/(u/_1,u/_2,…,u/_k/), /(?/)/_k∈C~/(n×k/),andlet /(?/)/_k be n×k and have orthogonal columns. If‖sin/(?/)/(U/_k,/(?/)/_k/)‖=O/(ε/),then trace/(/(?/)/_k~*A/(?/)/_k/)≥λ/_1+λ/_2+…+λ/_k+O/(ε~2/).whereε≥0, on the other hand, we extend to those for the singular values ofarbitrary matrix. Secondly, we consider the perturbation of the subeigenspace byRayleigh Quotient, and extend the corresponding result in Sun/[9/].