منابع مشابه
Backward errors and pseudospectra for structured nonlinear eigenvalue problems
Minimal structured perturbations are constructed such that an approximate eigenpair of a nonlinear eigenvalue problem in homogeneous form is an exact eigenpair of an appropriately perturbed nonlinear matrix function. Structured and unstructured backward errors are compared. These results extend previous results for (structured) matrix polynomials to more general functions. Structured and unstru...
متن کاملStructured Condition Numbers and Backward Errors in Scalar Product Spaces
We investigate the effect of structure-preserving perturbations on the solution to a linear system, matrix inversion, and distance to singularity. Particular attention is paid to linear and nonlinear structures that form Lie algebras, Jordan algebras and automorphism groups of a scalar product. These include complex symmetric, pseudo-symmetric, persymmetric, skewsymmetric, Hamiltonian, unitary,...
متن کاملPreconditioning KKT systems §
Standard preconditioners, such as ILU factorizations, often break down in construction for KKT matrices. We compare several approaches for preconditioning KKT systems. The first applies a constraint preconditioner by incorporating robust factored approximations of (BB ) and BB , where B is the (2,1) block of the KKT matrix. In the second approach, we apply permutations and scalings that maximiz...
متن کاملA Chart of Backward Errors for Singly and Doubly Structured Eigenvalue Problems
We present a chart of structured backward errors for approximate eigenpairs of singly and doubly structured eigenvalue problems. We aim to give, wherever possible, formulae that are inexpensive to compute so that they can be used routinely in practice. We identify a number of problems for which the structured backward error is within a factor √ 2 of the unstructured backward error. This paper c...
متن کاملBackward Error and Condition of Structured Linear Systems
Existing deenitions of backward error and condition number for linear systems do not cater for structure in the coeecient matrix, except possibly for sparsity. We extend the deenitions so that when the coeecient matrix has structure the perturbed matrix has this structure too. We show that when the structure comprises linear dependence on a set of parameters the structured componentwise backwar...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Linear Algebra and its Applications
سال: 1999
ISSN: 0024-3795
DOI: 10.1016/s0024-3795(98)10184-2