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An adaptive s -step conjugate gradient algorithm with dynamic basis updating

Erin Claire Carson (2020)

Applications of Mathematics

The adaptive s -step CG algorithm is a solver for sparse symmetric positive definite linear systems designed to reduce the synchronization cost per iteration while still achieving a user-specified accuracy requirement. In this work, we improve the adaptive s -step conjugate gradient algorithm by the use of iteratively updated estimates of the largest and smallest Ritz values, which give approximations of the largest and smallest eigenvalues of A , using a technique due to G. Meurant and P. Tichý (2018)....

An introduction to hierarchical matrices

Wolfgang Hackbusch, Lars Grasedyck, Steffen Börm (2002)

Mathematica Bohemica

We give a short introduction to a method for the data-sparse approximation of matrices resulting from the discretisation of non-local operators occurring in boundary integral methods or as the inverses of partial differential operators. The result of the approximation will be the so-called hierarchical matrices (or short ℋ -matrices). These matrices form a subset of the set of all matrices and have a data-sparse representation. The essential operations for these matrices (matrix-vector and matrix-matrix...

Applying approximate LU-factorizations as preconditioners in eight iterative methods for solving systems of linear algebraic equations

Zahari Zlatev, Krassimir Georgiev (2013)

Open Mathematics

Many problems arising in different fields of science and engineering can be reduced, by applying some appropriate discretization, either to a system of linear algebraic equations or to a sequence of such systems. The solution of a system of linear algebraic equations is very often the most time-consuming part of the computational process during the treatment of the original problem, because these systems can be very large (containing up to many millions of equations). It is, therefore, important...

Beitrag zu mehrparametrigen Iterationsverfahren für spezielle lineare Gleichungssysteme

Miroslav Šisler (1989)

Aplikace matematiky

Die Arbeit befasst sich mit der Anwendung eines gewissen mehrparametrigen Iterationsverfahrens bei der Lösung des linearen Gleichungsystems der Form x = B x + b , wo B eine gewisse, eine grosse Anzahl von Nullelementen enthaltende. Matrix bezeichnet und irgendeine von der Hauptuntermatrizen der Matrix B leicht invertierbar ist. Das, in der Arbeit vorgeschlagende Iterationsverfahren stellt eine Kombination des iterativen und direkten Verfahrens dar.

Complete solution of tropical vector inequalities using matrix sparsification

Nikolai Krivulin (2020)

Applications of Mathematics

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...

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