In this article, we consider the structured condition numbers for LDU, factorization by using the modified matrix-vector approach and the differential calculus, which can be represented by sets of parameters. By setti...In this article, we consider the structured condition numbers for LDU, factorization by using the modified matrix-vector approach and the differential calculus, which can be represented by sets of parameters. By setting the specific norms and weight parameters, we present the expressions of the structured normwise, mixed, componentwise condition numbers and the corresponding results for unstructured ones. In addition, we investigate the statistical estimation of condition numbers of LDU factorization using the probabilistic spectral norm estimator and the small-sample statistical condition estimation method, and devise three algorithms. Finally, we compare the structured condition numbers with the corresponding unstructured ones in numerical experiments.展开更多
Orthogonal projection methods have been widely used to solve linear systems. Little attention has been given to oblique projection methods, but the class of oblique projection methods is particularly attractive for la...Orthogonal projection methods have been widely used to solve linear systems. Little attention has been given to oblique projection methods, but the class of oblique projection methods is particularly attractive for large nonsymmetric systems. The purpose of this paper is to consider a criterion for judging whether a given appro ximation is acceptable and present an algorithm which computes an approximate solution to the linear systems Ax=b such that the normwise backward error meets some optimality condition.展开更多
In this paper, we investigate the condition numbers for indefinite least squares problem with multiple right-hand sides. The normwise, mixed and componentwise condition numbers and the corresponding structured conditi...In this paper, we investigate the condition numbers for indefinite least squares problem with multiple right-hand sides. The normwise, mixed and componentwise condition numbers and the corresponding structured condition numbers are presented. The structured matrices under consideration include the linear structured matrices, such as the Toeplitz, Hankel, symmetric, and tridiagonal matrices, and the nonlinear structured matrices, such as the Vandermonde and Cauchy matrices. Numerical examples show that the structured condition numbers are tighter than the unstructured ones.展开更多
In this paper,we consider the indefinite least squares problem with quadratic constraint and its condition numbers.The conditions under which the problem has the unique solution are first presented.Then,the normwise,m...In this paper,we consider the indefinite least squares problem with quadratic constraint and its condition numbers.The conditions under which the problem has the unique solution are first presented.Then,the normwise,mixed,and componentwise condition numbers for solution and residual of this problem are derived.Numerical example is also provided to illustrate these results.展开更多
基金Supported by the National Natural Science Foundation of China(11671060).
文摘In this article, we consider the structured condition numbers for LDU, factorization by using the modified matrix-vector approach and the differential calculus, which can be represented by sets of parameters. By setting the specific norms and weight parameters, we present the expressions of the structured normwise, mixed, componentwise condition numbers and the corresponding results for unstructured ones. In addition, we investigate the statistical estimation of condition numbers of LDU factorization using the probabilistic spectral norm estimator and the small-sample statistical condition estimation method, and devise three algorithms. Finally, we compare the structured condition numbers with the corresponding unstructured ones in numerical experiments.
文摘Orthogonal projection methods have been widely used to solve linear systems. Little attention has been given to oblique projection methods, but the class of oblique projection methods is particularly attractive for large nonsymmetric systems. The purpose of this paper is to consider a criterion for judging whether a given appro ximation is acceptable and present an algorithm which computes an approximate solution to the linear systems Ax=b such that the normwise backward error meets some optimality condition.
基金Supported by the National Natural Science Foundation of China(Grant No.11671060)the Fundamental Research Funds for the Central Universities(Grant No.106112015CDJXY100003)
文摘In this paper, we investigate the condition numbers for indefinite least squares problem with multiple right-hand sides. The normwise, mixed and componentwise condition numbers and the corresponding structured condition numbers are presented. The structured matrices under consideration include the linear structured matrices, such as the Toeplitz, Hankel, symmetric, and tridiagonal matrices, and the nonlinear structured matrices, such as the Vandermonde and Cauchy matrices. Numerical examples show that the structured condition numbers are tighter than the unstructured ones.
基金Supported by the National Natural Science Foundation of China(Grant No.11671060)the Fundamental Research Funds for the Central Universities(Grant No.106112015CDJXY100003)
文摘In this paper,we consider the indefinite least squares problem with quadratic constraint and its condition numbers.The conditions under which the problem has the unique solution are first presented.Then,the normwise,mixed,and componentwise condition numbers for solution and residual of this problem are derived.Numerical example is also provided to illustrate these results.
