Combined preorder and postorder traversal algorithm for the analysis of singular systems by Haar wavelets.
Combining the preconditioned conjugate gradient method and a matrix iterative method
The preconditioned conjugate gradient method for solving the system of linear algebraic equations with a positive definite matrix is investigated. The initial approximation for conjugate gradient is constructed as a result of a matrix iteration method after steps. The behaviour of the error vector for such a combined method is studied and special numerical tests and conclusions are made.
Communication balancing in parallel sparse matrix-vector multiplication.
Comparing multilevel coarsening strategies.
Comparison between different numerical discretizations for a Darcy-Forchheimer model.
Comparison of algorithms for calculation of the greatest common divisor of several polynomials
The computation of the greatest common divisor (GCD) has many applications in several disciplines including computer graphics, image deblurring problem or computing multiple roots of inexact polynomials. In this paper, Sylvester and Bézout matrices are considered for this purpose. The computation is divided into three stages. A rank revealing method is shortly mentioned in the first one and then the algorithms for calculation of an approximation of GCD are formulated. In the final stage the coefficients...
Comparison of Linear System Solvers Applied to Diffusion-Type Finite Element Equations.
Comparison of Splittings Used with the Conjugate Gradient Algorithm.
Comparison theorems for weak nonnegative splittings of -monotone matrices.
Comparison theorems for weak splittings of bounded operators.
Comparisons of Regular Splittings of Matrices.
Comparisons of Weak Regular Splittings and Multisplitting Methods.
Complete solution of tropical vector inequalities using matrix sparsification
We examine the problem of finding all solutions of two-sided vector inequalities given in the tropical algebra setting, where the unknown vector multiplied by known matrices appears on both sides of the inequality. We offer a solution that uses sparse matrices to simplify the problem and to construct a family of solution sets, each defined by a sparse matrix obtained from one of the given matrices by setting some of its entries to zero. All solutions are then combined to present the result in a...
Complexity issues for the symmetric interval eigenvalue problem
We study the problem of computing the maximal and minimal possible eigenvalues of a symmetric matrix when the matrix entries vary within compact intervals. In particular, we focus on computational complexity of determining these extremal eigenvalues with some approximation error. Besides the classical absolute and relative approximation errors, which turn out not to be suitable for this problem, we adapt a less known one related to the relative error, and also propose a novel approximation error....
Complexity of an algorithm for solving saddle-point systems with singular blocks arising in wavelet-Galerkin discretizations
The paper deals with fast solving of large saddle-point systems arising in wavelet-Galerkin discretizations of separable elliptic PDEs. The periodized orthonormal compactly supported wavelets of the tensor product type together with the fictitious domain method are used. A special structure of matrices makes it possible to utilize the fast Fourier transform that determines the complexity of the algorithm. Numerical experiments confirm theoretical results.
Componentwise Inclusion and Exclusion Sets for Solutions of Quadratic Equations in Finite Dimensional Spaces.
Composite grid finite element method: Implementation and iterative solution with inexact subproblems
This paper concerns the composite grid finite element (FE) method for solving boundary value problems in the cases which require local grid refinement for enhancing the approximating properties of the corresponding FE space. A special interest is given to iterative methods based on natural decomposition of the space of unknowns and to the implementation of both the composite grid FEM and the iterative procedures for its solution. The implementation is important for gaining all benefits of the described...
Computation of bifurcated branches in a free boundary problem arising in combustion theory
We consider a parabolic 2D Free Boundary Problem, with jump conditions at the interface. Its planar travelling-wave solutions are orbitally stable provided the bifurcation parameter does not exceed a critical value . The latter is the limit of a decreasing sequence of bifurcation points. The paper deals with the study of the 2D bifurcated branches from the planar branch, for small k. Our technique is based on the elimination of the unknown front, turning the problem into a fully nonlinear...
Computation of determinants and inverses of rectangular or singular matrices using residue arithmetic.
Computation of eigenvalue and eigenvector derivatives for a general complex-valued eigensystem.