Riemann‐Hilbert problem and matrix discrete Painlevé II systems

Matrix Szeg? biorthogonal polynomials for quasi‐definite matrices of Hölder continuous weights are studied. A Riemann‐Hilbert problem is uniquely solved in terms of the matrix Szeg? polynomials and its Cauchy transforms. The Riemann‐Hilbert problem is given as an appropriate framework for the discussion of the Szeg? matrix and the associated Szeg? recursion relations for the matrix orthogonal polynomials and its Cauchy transforms. Pearson‐type differential systems characterizing the matrix of weights are studied. These are linear systems of ordinary differential equations that are required to have trivial monodromy. Linear ordinary differential equations for the matrix Szeg? polynomials and its Cauchy transforms are derived. It is shown how these Pearson systems lead to nonlinear difference equations for the Verblunsky matrices and two examples, of Fuchsian and non‐Fuchsian type, are considered. For both cases, a new matrix version of the discrete Painlevé II equation for the Verblunsky matrices is found. Reductions of these matrix discrete Painlevé II systems presenting locality are discussed.     

两类模糊数判断矩阵的转换关系及一致性研究

研究了三角模糊数互反和互补判断矩阵的相互转换和一致性问题.提出了三角模糊数互反判断矩阵完全一致性的定义以及三角模糊数互补判断矩阵加性一致性和乘性一致性的定义,给出了两类模糊数判断矩阵相互转化的公式,论证了转换公式对判断矩阵一致性的保持关系.最后,基于一致性模糊数判断矩阵元素和排序权值的关系,建立了两个方案排序的非线性规划模型.     

The Bezoutian and the eigenvalue-separation problem for matrix polynomials

A generalized Bezout matrix for a pair of matrix polynomials is studied and, in particular, the structure of its kernel is described and the relations to the greatest common divisor of the given matrix polynomials are presented. The classical root-separation problems of Hermite, Routh-Hurwitz and Schur-Cohn are solved for matrix polynomials in terms of this Bezout matrix. The eigenvalue-separation results are also expressed in terms of Hankel matrices whose entries are Markov parameters of rational matrix function. Some applications of Jacobi's method to these problems are pointed out.     

粗糙集的矩阵关系

将粗糙集中的集合转化为矩阵刻画,通过引入矩阵算子、类矩阵算子,借助截矩阵和关系矩阵,讨论了Paw lak粗糙集和变精度粗糙集中集合关系的矩阵计算及其所具有的一些基本性质.     

Convergence of Fixed-Point Continuation Algorithms for Matrix Rank Minimization

The matrix rank minimization problem has applications in many fields, such as system identification, optimal control, low-dimensional embedding, etc. As this problem is NP-hard in general, its convex relaxation, the nuclear norm minimization problem, is often solved instead. Recently, Ma, Goldfarb and Chen proposed a fixed-point continuation algorithm for solving the nuclear norm minimization problem (Math. Program., doi:, 2009). By incorporating an approximate singular value decomposition technique in this algorithm, the solution to the matrix rank minimization problem is usually obtained. In this paper, we study the convergence/recoverability properties of the fixed-point continuation algorithm and its variants for matrix rank minimization. Heuristics for determining the rank of the matrix when its true rank is not known are also proposed. Some of these algorithms are closely related to greedy algorithms in compressed sensing. Numerical results for these algorithms for solving affinely constrained matrix rank minimization problems are reported.     

r-置换矩阵的一些性质

本文针对正交表和置换群中的置换矩阵问题,提出了r-置换矩阵的概念,研究了其性质,并且给出这类矩阵逆的求法以及利用Hadamard积得出确定方阵为r-置换矩阵的充要条件,对于我们研究和推广置换矩阵有极其重要的意义。     

An algorithm for recognising the exterior square of a matrix

We describe a polynomial-time algorithm for recognising the exterior square of a matrix. The approach involves manipulation of the equations which relate the entries of a matrix and the entries of its exterior square. Conditions are given which are necessary and sufficient for two matrices to have the same exterior square. The definition of the exterior square of a matrix, and the algorithm used to recognise one, are both easily extended to matrix groups.     

Sharp bounds on the spectral radius of a nonnegative matrix

We give upper and lower bounds for the spectral radius of a nonnegative matrix using its row sums and characterize the equality cases if the matrix is irreducible. Then we apply these bounds to various matrices associated with a graph, including the adjacency matrix, the signless Laplacian matrix, the distance matrix, the distance signless Laplacian matrix, and the reciprocal distance matrix. Some known results in the literature are generalized and improved.     

线性泛函微分方程关于部分变元稳定性的充要条件

本文在引进具有界滞量线性泛函微分方程的Cauchy矩阵的截断矩阵与截断解算子概念的基础上 ,讨论了这类方程关于部分变元各种稳定性的充要条件 .本文包含此类方程相应的关于全体变元稳定性的经典结论为其特例 .     

Congruence and conjunctivity of matrices to their adjoints

Every square matrix over a field F is involutorily congruent over F to its transpose, and hence each such matrix is the product of a symmetric matrix and an involutory matrix over F. In the usual complex case every matrix which is conjunctive with its adjoint (=conjugate-transpose) is involutorily conjunctive with its adjoint and hence is the product of a hermitian matrix and an involutory matrix; furthermore every such matrix is conjunctive with a real matrix. These three conditions on a matrix, (1) being conjunctive with its adjoint, (2) being involutorily conjunctive with its adjoint, and (3) being conjunctive with a real matrix, are studied in the more general context of a field F with involution, and it is shown in general that (3) implies (2), that (2) implies (3) if char F≠2 (a 2×2 counterexample exists for each F with char F=2), and that (1) does not in general imply (2) (a 2×2 counterexample in the complexification of the rational field is presented). The problem of deciding which matrices satisfy (2) is equivalent (even in this general context) to the problem of deciding which pairs of self-adjoint (“hermitian”) matrices are involutorily conjunctive. For the general 2×2 case, the three conditions are characterized in terms of norms.     

广义Jacobi矩阵的逆特征问题

本文主要讨论广义Jacobi阵及多个特征对的广义Jacobi阵逆特征问题.通过相似变换将广义Jacobi阵变换为三对角对称矩阵,其特征不变、特征向量只作线性变换,再应用前人理论求得广义Jacobi阵元素ai,|bi|,|ci|有唯一解的充要条件及其具体表达式.     

Cones, graphs and optimal scalings of matrices

Characterizations are given of the optimal scalings of a complex square matrix within its diagonal similarity class and its restricted diagonal equivalence class with respect to the maximum element norm. The characterizations are in terms of a finite number of products, principally circuit and diagonal products. The proofs proceed by reducing the optimal scaling problems from the multiplicative matrix level in succession to an additive matrix level, a graph theoretic level, and a geometric level involving duality theorems for cones. At the geometric level, the diagonal similarity and the restricted diagonal equivalence problems are unified.     

The solvability conditions for inverse problems of anti-symmetric ortho-symmetric matrices

This paper discusses the anti-symmetric ortho-symmetric solution of a linear matrix equation and its optimal approximation. The necessary and sufficient conditions for the solvability of the matrix equation and the general expression of the anti-symmetric ortho-symmetric solution are given. In addition, the existence and uniqueness of the optimal approximation are proved. Numerical methods of the optimal approximation to a given matrix and numerical experiments are described.     

The inverse eigenvalue problem for symmetric quasi anti-bidiagonal matrices

In this paper we construct the symmetric quasi anti-bidiagonal matrix that its eigenvalues are given, and show that the problem is also equivalent to the inverse eigenvalue problem for a certain symmetric tridiagonal matrix which has the same eigenvalues. Not only elements of the tridiagonal matrix come from quasi anti-bidiagonal matrix, but also the places of elements exchange based on some conditions.     

Morita equivalence for infinite matrix rings

In this paper, weak distinguished subcategory and distinguished subcategory of modules are introduced. Left(right) local unital rings are particularly considered. Also, representable equivalent functors between categories. By using the replacement techniques of modules, a general theory of Morita equivalence for infinite matrix rings is established. This theory not only extends the classical Morita theory of equivalence from finite matrix rings to infinite matrix rings and also contains some new results which are useful in studying the algebraic structures for infinite matrix rings. Some results of classical Morita theory are included as its special cases.     

Inverse Spectrum Problems for Block Jacobi Matrix

By establishing the spectrum (matrix) function for the block Jacobi matrix, theorems of existence and uniqueness for the inverse problem and algorithms for its solution are obtained. The study takes into account all possible multiple-eigenvalue cases that are very difficult to deal with by other means.     

Matrix correction of a dual pair of improper linear programming problems

A matrix is sought that solves a given dual pair of systems of linear algebraic equations. Necessary and sufficient conditions for the existence of solutions to this problem are obtained, and the form of the solutions is found. The form of the solution with the minimal Euclidean norm is indicated. Conditions for this solution to be a rank one matrix are examined. On the basis of these results, an analysis is performed for the following two problems: modifying the coefficient matrix for a dual pair of linear programs (which can be improper) to ensure the existence of given solutions for these programs, and modifying the coefficient matrix for a dual pair of improper linear programs to minimize its Euclidean norm. Necessary and sufficient conditions for the solvability of the first problem are given, and the form of its solutions is described. For the second problem, a method for the reduction to a nonlinear constrained minimization problem is indicated, necessary conditions for the existence of solutions are found, and the form of solutions is described. Numerical results are presented.     

Analytical aspects of computational linear algebra

This paper deals with a system of ordinary differential equations with known initial conditions associated with a given square matrix. By using standard analytical and computational methods many of the important aspects of the given matrix can be determined. Among these are its determinant, its adjoint, its inverse (if it exist), the coefficients of the characteristic polynomial, the location of the roots ofthe characteristic polynomial, and the corresponding eigenvectors. Concomitently, the differential system yields a treatment of inhomogeneous linear algebraic systems associated with the given matrix, as in economic input-output analysis. In particular, new insights are provided into Faddeev's algorithm for the coefficients of the characteristic polynomial.