A = （aij） Rn×n is termed bisymmetric matrix if We denote the set of all n×n bisymmetric matrices by BSRn×n Let Where when n =2k, and n = 2k+1, In this paper, we discuss the following two problems: Problem Ⅰ. Given X Rn×m, B Rn×m. Find A S such that Problem Ⅱ. Given A* E Rn×n. Find A SE such that Where is Frobenius norm, and SE is the solution set of Problem I. In this paper the general representation of SE has been given. The necessary and sufficient conditons have been presented for Problem I0. For Problem Ⅱ the expression of the solution has been provided.
In this paper, we consider the following two problems: Problem i. Given X ∈ Rmxn,A = diag（λ1,…, λm） > 0, find A E BSR such that where ||AX-X∧||=min, is Frobenius norm, BSR: is the set of all n x n bisymmetric nonnegative definite matrices. Problem Ⅱ. Given A* ∈ Rnxn, find ALS ∈ SE such that||A*-ALS||=inf||A*-A|| where SE is the solution set of problem Ｉ. The existence of the solution for problem Ⅰ, Ⅱ and the uniqueness of the solution for Problem Ⅱ are proved. The general form of SE is given and the expression of ALS is presented.
A=（aij） ∈Rn×n is termed bisymmetric matrix if We denote the set of all n × n bisymmetric matrices by BSRn×n In this paper, we discuss the following two problems: Problem I. Given X, Find such that Problem Ⅱ. Gived . Find such that where ||·|| is Frobenius norm, and SE is the solution set of Problem I. The general form of SE has been given. The necessary and sufficient conditions have been studied for the special cases AX = B and AX = XA of problem I. For problem Ⅱ the expression of the solution has been provided.
