Two popular non-overlapping domain decomposition methods, the FETI–DP and BDDC algorithms, are reformulated using Block Cholesky factorizations, an approach which can provide a useful framework for the design of domain decomposition algorithms for solving symmetric positive definite linear system of equations. Instead of introducing Lagrange multipliers to enforce the coarse level, primal conti...

Block (including s-step) iterative methods for (non)symmetric linear systems have been studied and implemented in the past. In this article we present a (combined) block s-step Krylov iterative method for nonsymmetric linear systems. We then consider the problem of applying any block iterative method to solve a linear system with one right-hand side using many linearly independent initial resid...

This thesis is a contribution to the field of algebraic cryptanalysis. Specifically the following topics have been studied: • We construct and analyze Feistel and SLN ciphers that have a sound design strategy against linear and differential cryptanalysis. The encryption process for these cipher can be described by very simple polynomial equations. For a block and key size of 128 bits, we presen...

Some block Toeplitz methods applied to polynomial matrices are reviewed. We focus on the computation of the structure (rank, null-space, infinite and finite structures) of an arbitrary rectangular polynomial matrix. We also introduce some applications of this structural information in control theory. All the methods outlined here are based on the computation of the null-spaces of suitable block...

This research aims at creating and providing a framework to describe algorithmic redistribution methods for various block cyclic decompositions. To do so properties of this data distribution scheme are formally exhibited. The examination of a number of basic dense linear algebra operations illustrates the application of those properties. This study analyzes the extent to which the general two-d...

We extend the theory of Multigrid methods developed for PDE, Toeplitz and related matrices to the Block Toeplitz case. Prolongations and restrictions are defined depending on the zeroes of the generating function of the Block Toeplitz matrix. On numerical examples we compare different choices for prolongations and restrictions.

We study and develop (stochastic) primal–dual block-coordinate descent methods based on the method of Chambolle and Pock. Our methods have known convergence rates for the iterates and the ergodic gap: O(1/N 2) if each each block is strongly convex, O(1/N ) if no convexity is present, and more generally a mixed rate O(1/N 2) + O(1/N ) for strongly convex blocks, if only some blocks are strongly ...

Recent several years have witnessed the surge of asynchronous (async-) parallel computing methods due to the extremely big data involved in many modern applications and also the advancement of multi-core machines and computer clusters. In optimization, most works about async-parallel methods are on unconstrained problems or those with block separable constraints. In this paper, we propose an as...