Browsing by Author "Hadjidimos, A."
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Identification of classes of Hmatrices
Bru, R.; Giménez, I.; Hadjidimos, A. (2010)Hmatrices play an important role in the theory and applications. Different algorithms to determine Hmatrices can be found in the literature. In [1] an algorithm is given, and this algorithm can determine if an irreducible ... 
Irreducibility and extensions of Ostrowski's Theorem
Hadjidimos, A. (2012)In this paper an extension of Ostrowski's Theorem for complex square irreducible matrices is presented. Also extensions of similar statements for square complex matrices are analyzed and completed. Most of the statements ... 
Is A is an element of Cn,Cn a general Hmatrix?
Bru, R.; Gimenez, I.; Hadjidimos, A. (2012)Hmatrices play an important role in the theory and applications of Numerical Linear Algebra. So, it is very useful to know whether a given matrix A is an element of Cn,Cn, usually the coefficient of a complex linear ... 
The matrix analogue of the scalar AOR iterative method
Hadjidimos, A. (2015)The Accelerated Overrelaxation (AOR) and the Generalized AOR (GAOR) iterative methods for the solution of linear systems of algebraic equations (Ax = b, A is an element of Cnxn, det(A) not equal 0, b is an element of Cn) ... 
MINIMIZATION OF THE SPECTRAL NORM OF THE SOR OPERATOR IN A MIXED CASE
Hadjidimos, A.; Stratis, P. (2007)In this work we solve the problem of the minimization of the spectral norm of the SOR operator associated with a block twocyclic consistently ordered matrix A epsilon Cn,Cn, assuming that the corresponding Jacobi matrix ... 
A new iterative criterion for Hmatrices: The reducible case
Alanelli, M.; Hadjidimos, A. (2008)Hmatrices appear in various areas of science and engineering and it is of vital importance to have an Algorithm to identify the Hmatrix character of a certain matrix A epsilon Cn,Cn. Recently, the present authors have ... 
Nonstationary Extrapolated Modulus Algorithms for the solution of the Linear Complementarity Problem
Hadjidimos, A.; Tzoumas, M. (2009)The Linear Complementarity Problem (LCP) has many applications as, e.g., in the solution of Linear and Convex Quadratic Programming, in Free Boundary Value problems of Fluid Mechanics, etc. In the present work we assume ... 
A note on Ostrowski's Theorem
Hadjidimos, A. (2013)In this note, a further extension of Ostrowski's Theorem, concerning mainly complex square irreducible matrices, is presented. Specifically, classes of irreducible matrices are determined for which the classical statement: ... 
On BrauerOstrowski and Brualdi sets
Hadjidimos, A.; Tzoumas, M. (2014)For the localization of the spectrum of the eigenvalues of a complex square matrix, the classical Gersgorin Theorem was extended by Ostrowski who used the generalized geometric mean of the row and column sums of the matrix. ... 
ON ITERATIVE SOLUTION FOR LINEAR COMPLEMENTARITY PROBLEM WITH AN H+MATRIX
Hadjidimos, A.; Lapidakis, M.; Tzoumas, M. (2012)The numerous applications of the linear complementarity problem (LCP) in, e.g., the solution of linear and convex quadratic programming, free boundary value problems of fluid mechanics, and moving boundary value problems ... 
On the choice of parameters in MAOR type splitting methods for the linear complementarity problem
Cvetkovic, L.; Hadjidimos, A.; Kostic, V. (2014)In the present work we consider the iterative solution of the Linear Complementarity Problem (LCP), with a nonsingular H (+) coefficient matrix A, by using all modulusbased matrix splitting iterative methods that have ... 
On the optimal complex extrapolation of the complex Cayley transform
Hadjidimos, A.; Tzoumas, M. (2009)The Cayley transform, F := F(A) = (I + A)(1) (I  A), with A epsilon C(n.n) and 1 is not an element of sigma (A), where sigma(.) denotes spectrum, and its extrapolated counterpart F (omega A), omega epsilon C\{0} and 1 ... 
On the Solution of the Linear Complementarity Problem by the Generalized Accelerated Overrelaxation Iterative Method
Hadjidimos, A.; Tzoumas, M. (2015)In the present work, we determine intervals of convergence for the various parameters involved for what is known as the generalized accelerated overrelaxation iterative method for the solution of the linear complementarity ... 
Optimization of extrapolated Cayley transform with nonHermitian positive definite matrix
Bai, Z. Z.; Hadjidimos, A. (2014)For the extrapolated Cayley transform, we give necessary and sufficient conditions for guaranteeing its convergence and contraction (in the Euclidean norm). We derive upper bounds for the convergence and the contraction ... 
The principle of extrapolation and the Cayley Transform
Hadjidimos, A.; Tzoumas, M. (2008)The Cayley Transform, F := (I + A)(1)(I  A), with A is an element of Cn,Cn and 1 is not an element of sigma (A), where sigma(.) denotes spectrum, is of significant theoretical importance and interest and has many ... 
Special Issue: Proceedings of NUMAN 2007 Conference: Recent Approaches to Numerical Analysis: Theory, Methods and Applications Preface
Gallopoulos, E.; Hadjidimos, A.; Kotsireas, I. S.; Noutsos, D.; Vrahatis, M. N. (2009) 
Stationary biparametric ADI preconditioners for conjugate gradient methods
Hadjidimos, A.; Lapidakis, M. (2007)In the present article we determine optimal stationary biparametric ADI preconditioners for the conjugate gradient methods when applied for the solution of a model problem second order elliptic PDE. The PDE is approximated ...