On spectral properties of multiparameter polynomial matrices

In the present paper, methods and algorithms for numerical solution of spectral problems and some problems in algebra related to them for one- and two-parameter polynomial and rational matrices are considered. A survey of known methods of solving spectral problems for polynomial matrices that are based on the rank factorization of constant matrices, i.e., that apply the singular value decomposition (SVD) and the normalized decomposition (the QR factorization), is given. The approach to the construction of methods that makes use of rank factorization is extended to one- and two-parameter polynomial and rational matrices. Methods and algorithms for solving some parametric problems in algebra based on ideas of rank factorization are presented. Bibliography: 326titles.

Essential spectra of singular matrix differential operators of mixed order

We consider boundary value problems for elliptic systems in the sense of Agmon-Douglis-Nirenberg on plane domains with corners, where the domain, the coefficients of the operators and the right hand sides all depend on a parameter. We construct corner singularities in such a way that the corresponding decomposition of the solution into regular and singular parts is stable, i. e. the regular part and the coefficient of the singular functions depend smoothly on the parameter. The construction of these singular functions continues the paper [3] and generalizes results known for second order scalar boundary value problems — see [4,5] [12]. Additional informationNotes on contributors Martin Costabel Monique Dauge

The author studies the structure of solutions to the interface problems for second order linear elliptic partial differential equations in three space dimension. The set of singular points consists of some singular lines and some isolated singular points. It is proved that near a singular line or a singular point, each weak solution can be decomposed into two parts, a singular part and a regular part. The singular parts are some finite sum of particular solutions to some simpler equations, and the regular parts are bounded in some norms, which are slightly weaker than that in the Sobolev space H2.

Inversion components of block Hankel-like matrices

New remarks on the factorization and equivalence problems for a class of multivariate polynomial matrices

As an important secretive attribute, opacity of cyber-physical systems (CPSs) has attracted considerable attention. Existing works on opacity mainly concentrate on the formal language method by assuming that the intruder tracks partial knowledge of observable transitions. In this paper, under the framework of Boolean semi-tensor product (BSTP) of matrix, we extend the verification of opaque property to algebraic mechanisms that have great advantages in problem description and solution. First, we show that how [Formula: see text]-step opacity problem of nondeterministic finite automata (NFAs) can be transformed to the construction problem of a polynomial matrix that characterizes the state estimation eavesdropped by malicious intruders within the last [Formula: see text] observations. Second, the necessary and sufficient condition of verifying [Formula: see text]-step opacity is obtained, which is equivalent to validate the composition of elements within the polynomial matrix. Finally, the effectiveness of this result is demonstrated by an illustrative example. Taking together, the matrix-based method will be useful to deliver a novel theoretical tool for investigating the privacy-preserving problem in the related area of CPSs.

By means of the discrete zero curvature representation, the coupled Bogoyavlensky lattice 1(2) hierarchy related to a $$3\times 3$$ matrix problem is derived. Resorting to the characteristic polynomial of Lax matrix for the lattice hierarchy, we introduce a trigonal curve $$\mathcal {K}_{m-1}$$ of arithmetic genus $$m-1$$ and construct the related Baker–Akhiezer function and meromorphic function. By analyzing the asymptotic expansion of the meromorphic function, the algebro-geometric solutions to the stationary coupled Bogoyavlensky lattice 1(2) are obtained. Moreover, the explicit theta function representations for the coupled Bogoyavlensky lattice hierarchy are given with the help of the Abelian differential.

In an early stage of studies concerned with lifting-surface theory for ship screws, the Netherlands Ship Model Basin initiated the development of a numerical solution of the mathematical model. To achieve this, a rigorous method was followed consisting of separation of regular and singular parts of the kernel of the integral equation, preparation of numerical procedures for integration of the regular parts, and analytical integration of the singular parts. The general solution includes the steady load due to blade geometry in uniform flow, the unsteady load in nonuniform flow, and the unsteady load due to propeller vibrations. The pressure distribution in the chordwise direction is represented by a series of linear combinations of Chebyshev polynomials. In this paper an account is given of this method of solution.

It is well known that in the case of a regular domain the solution of the time-harmonic Maxwell's equations allows a discretization by means of nodal finite elements: this is achieved by solving a regularized problem similar to the vector Helmholtz equation. The present paper deals with the same problem in the case of a nonconvex polyhedron. It is shown that a nodal finite element method does not approximate in general the solution to Maxwell's equations, but actually the solution to a neighboring variational problem involving a different function space. Indeed, the solution to Maxwell's equations presents singularities near the edges and corners of the domain that cannot be approximated by Lagrange finite elements. A new method is proposed involving the decomposition of the solution field into a regular part that can be treated numerically by nodal finite elements and a singular part that has to be taken into account explicitly. This singular field method is presented in various situations such as electric and magnetic boundary conditions, inhomogeneous media, and regions with screens.

For the parabolic Lamé system on polygonal domains: The transport equation

We reduce the problem of computing the rank and a null-space basis of a univariate polynomial matrix to polynomial matrix multiplication. For an input n x n matrix of degree, d over a field K we give a rank and nullspace algorithm using about the same number of operations as for multiplying two matrices of dimension, n and degree, d. If the latter multiplication is done in MM(n,d)= O~(nωd operations, with ω the exponent of matrix multiplication over K, then the algorithm uses O~MM(n,d) operations in, K. For m x n matrices of rank r and degree d, the cost expression is O(nmr ω-2d). The soft-O notation O~ indicates some missing logarithmic factors. The method is randomized with Las Vegas certification. We achieve our results in part through a combination of matrix Hensel high-order lifting and matrix minimal fraction reconstruction, and through the computation of minimal or small degree vectors in the nullspace seen as a K[x]-module.

Spaces of multiparameter rational vectors, i.e., of vectors whose components are rational functions in several variables, and polynomial bases of their subspaces are considered. The conjecture that any subspace in the space of multiparameter rational vectors possesses a “free” polynomial basis, i.e., a basis such that the associated basis multiparameter polynomial matrix has no finite regular spectrum, is disproved by an example. Some consequences of this fact are indicated. Simpler proofs of some properties of the singular spectra of basis polynomial matrices corresponding to the null-spaces of a singular polynomial matrix are presented. Bibliography: 5 titles.

This goal of this chapter is to find finitely many canonical representatives of each similarity class of square matrices with entries in a field and correspondingly of each isomorphism class of linear maps from a finite-dimensional vector space to itself.Section 1 frames the problem in more detail. Section 2 develops the theory of determinants over a commutative ring with identity in order to be able to work easily with characteristic polynomials det(?I — A). The discussion is built around the principle of "permanence of identities," which allows for passage from certain identities with integer coefficients to identities with coefficients in the ring in question.Section 3 introduces the minimal polynomial of a square matrix or linear map. The Cayley-Hamilton Theorem establishes that such a matrix satisfies its characteristic equation, and it follows that the minimal polynomial divides the characteristic polynomial. It is proved that a matrix is similar to a diagonal matrix if and only if its minimal polynomial is the product of distinct factors of degree 1. In combination with the fact that two diagonal matrices are similar if and only if their diagonal entries are permutations of one another, this result solves the canonical-form problem for matrices whose minimal polynomial is the product of distinct factors of degree 1.Section 4 introduces general projection operators from a vector space to itself and relates them to vector-space direct-sum decompositions with finitely many summands. The summands of a directsum decomposition are invariant under a linear map if and only if the linear map commutes with each of the projections associated to the direct-sum decomposition.Section 5 concerns the Primary Decomposition Theorem, whose subject is the operation of a linear map L: V ? V with V finite-dimensional. The statement is that if L has minimal polynomial \( P_1 (\lambda )^{l_1 } \cdots P_k (\lambda )^{l_k } \) with the Pj (?) distinct monic prime, then V has a unique direct-sum decomposition in which the respective summands are the kernels of the linear maps \( P_j (L)^{l_j } \), and moreover the minimal polynomial of the restriction of L to the j th summand is \( P_j (\lambda )^{l_j } \).Sections 6–7 concern Jordan canonical form. For the case that the prime factors of the minimal polynomial of a square matrix all have degree 1, the main theorem gives a canonical form under similarity, saying that a given matrix is similar to one in "Jordan form" and that the Jordan form is completely determined up to permutation of the constituent blocks. The theorem applies to all square matrices if the field is algebraically closed, as is the case for C. The theorem is stated and proved in Section 6, and Section 7 shows how to make computations in two different ways.

An improved uniformly convergent scheme in space for 1D parabolic reaction–diffusion systems