Sparse Matrices
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. Parallel Implementations of RCM Algorithm for Bandwidth Reduction of Sparse Matrices
RESUMO O algoritmo Reverse Cuthil-McKee (RCM) constitui uma heurística bem conhecida para o reordenamento de matrizes esparsas. Ele é tipicamente aplicado para a melhoria do desempenho da computação de sistemas lineares de equações. Este artigo descreve duas abordagens paralelas propostas para o algoritmo Reverse Cuthill-McKee, assim como versões otim
TEMA (São Carlos). Publicado em: 2017-12
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2. A new block algorithm for full-rank solution of the Sylvester-observer equation
A new block algorithm for computing a full rank solution of the Sylvester-observer equation arising in state estimation is proposed. The major computational kernels of this algorithm are: 1) solutions of standard Sylvester equations, in each case of which one of the matrices is of much smaller order than that of the system matrix and (furthermore, this small
Publicado em: 2011
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3. Códigos LDPC quaternários aplicados à técnica de transmissão OFDM / Quaternary LDPC codes applied to OFDM transmission technique
This dissertation addresses the study of error correcting codes based on sparse non-binary matrices. The LDPC (Low Density Parity Check) codes constitute a efficient family of codes generated by sparse parity check matrices and it is considered as one of the classes of codes that presents the best performance in digital communications systems. LDPC codes ove
Publicado em: 2010
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4. Espectro e dimensão Hausdorff de operadores bloco-Jacobi com perturbações esparsas distribuídas aleatoriamente / Spectrum and Hausdorff dimension of block-Jacobi matrices with sparse perturbations randomly distributed
Neste trabalho buscamos caracterizar o espectro de uma classe de operadores bloco--Jacobi limitados definidos em $l^2(\Lambda,\mathbb{C}^L)$ ($\Lambda: \mathbb{Z}_+\times\{0,1,\ldots,L-1\}$ representa uma faixa de largura $L\ge 2$ no semi--plano $\mathbb{Z}_+^2$) e sujeitos a perturbações esparsas (no sentido que as distâncias entre as ``barreirascrescem
Publicado em: 2010
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5. Tensorização de matrizes de rigidez para quadrados e hexaedros finitos de alta ordem / Tensorization of stiffness matrices for squares and hexaedral using high order FEM
High-order Finite Element Methods have been applied with success to problems of Fluid Dynamics and Electromagnetism. The main feature of these methods is to present an exponential convergence rate for problems with polinomial solution. However, due to the use of high-order interpolation functions, the elemental matrices are denser. This work shows a mathemat
Publicado em: 2009
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6. DecodificaÃÃo iterativa de cÃdigos baseados em matrizes de verificaÃÃo de paridade esparsas / Iterative decoding of codes based on sparse parity-check matrices
CÃdigos baseados em matrizes esparsas tÃm desempenhado um importante papel em teoria da codificaÃÃo. Os cÃdigos low-density parity-check (LDPC) constituem uma famosa famÃlia de cÃdigos definidos a partir de matrizes de verificaÃÃo de paridade esparsas que apresentam desempenhos excelentes no canal com ruÃdo aditivo Gaussiano branco (RAGB). O sucess
Publicado em: 2007
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7. New developments on BE/BE multi-zone algorithms based on krylov solvers: applications to 3D frequency-dependent problems
In this paper, new developments concerning the use of BE/BE coupling algorithms for solving 3D time-harmonic problems are reported. The algorithms are derived by considering different iterative solvers. Their chief idea is to work with the global sparse matrix of the coupled system, however without considering the many zero blocks associated with the non-cou
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2004-06
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8. An interior point method for constrained saddle point problems
We present an algorithm for the constrained saddle point problem with a convex-concave function L and convex sets with nonempty interior. The method consists of moving away from the current iterate by choosing certain perturbed vectors. The values of gradients of L at these vectors provide an appropriate direction. Bregman functions allow us to define a curv
Computational & Applied Mathematics. Publicado em: 2004
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9. RESEQUENCING TECHNIQUES FOR SOLVING LARGE SPARSE SYSTEMS / TÉCNICAS DE REORDENAÇÃO PARA SOLUÇÃO DE SISTEMAS ESPARSOS
Este trabalho apresenta técnicas de reordenação para minimização de banda, perfil e frente de malhas de elementos finitos. Um conceito unificado relacionando as malhas de elementos finitos, os grafos associados e as matrizes correspondentes é proposto. As informações geométricas, disponíveis nos programans de elemnetos finitos, são utilizadas para
Publicado em: 1995
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10. Simulação numerica de reservatorios utilizando um metodo de implicitude auto-adaptavel
This work presents the development and application of a reservoir simulation method, based on a variable ando auto-adaptive implicit formulation. The variable implicitness formulation is based on a general approach of reservoir simulation methods, already presented in the literature. In such approach a basic leveI of implicitness for alI methods is recognize
Publicado em: 1990
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11. Sparse nonnegative solution of underdetermined linear equations by linear programming
Consider an underdetermined system of linear equations y = Ax with known y and d × n matrix A. We seek the nonnegative x with the fewest nonzeros satisfying y = Ax. In general, this problem is NP-hard. However, for many matrices A there is a threshold phenomenon: if the sparsest solution is sufficiently sparse, it can be found by linear programming. We expl
National Academy of Sciences.