Papers by Efstratios Gallopoulos
Abstract We present methods designed to enhance the performance of a parallel ocean circulation m... more Abstract We present methods designed to enhance the performance of a parallel ocean circulation model (OCM). The underlying code is based on a primitive equations model of the Mediterranean Sea. We examine the characteristics of this basin and study the tradeoffs between minimising computations by avoiding sweeping over land areas vs. the higher computational rates achieved otherwise for a cluster based multiprocessor with hierarchical memory. Numerical experiments on Cedar, an architecture consisting of clusters of ...
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Scientific computation, Jul 26, 2015
In this chapter, we briefly present the main concepts in parallel computing. This is an attempt t... more In this chapter, we briefly present the main concepts in parallel computing. This is an attempt to make more precise some definitions that will be used throughout this book rather than a survey on the topic. Interested readers are referred to one of the many books available on the subject, e.g. Arbenz and Petersen, Introduction to Parallel Computing, (2004), Bertsekas and Tsitsiklis, Parallel and Distributed Computation, (1989), Culler et al. Parallel Computer Architecture: A Hardware/Software Approach, (1998), Kumar et al. Introduction to Parallel Computing: Design and Analysis of Algorithms, 2nd edn., (2003), Casanova et al. Parallel Algorithms, (2008), Hennessy and Patterson, Computer Architecture: A Quantitative Approach, (2011), Hockney and Jesshope, Parallel Computers 2: Architecture, Programming and Algorithms, 2nd edn., (1988), Tchuente, Parallel Computation on Regular Arrays. Algorithms and Architectures for Advanced Scientific Computing, (1991) [1, 2, 3, 4, 5, 6, 7, 8].
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Springer eBooks, 2008
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Springer eBooks, Feb 1, 2006
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Scientific computation, 2016
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Springer eBooks, 2012
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Scientific computation, Jul 26, 2015
Sparse linear systems occur in a multitude of applications in computational science and engineeri... more Sparse linear systems occur in a multitude of applications in computational science and engineering. While the need for solving such linear systems is most prevalent in numerical simulations using mathematical models based on differential equations, it also arises in other areas. For example, the PageRank vector that was used by Google to order the nodes of a network based on its link structure can be interpreted as the solution of a linear system of order equal to the number of nodes (Brin and Page, The anatomy of a large-scale hypertextual web search engine. In: Proceedings of 7th Intnational Conference World Wide Web, (1998), Langville and Meyer, Google’s PageRank and Beyond: The Science of Search Engine Rankings, (2006) [1, 2]). The system can be very large and sparse so that parallel iterative methods become necessary; see e.g. (Gleich et al. Fast parallel pagerank: a linear system approach, (2004), Gleich et al. SIAM J. Sci. Comput. 32(1), (2010) [3, 4]). We note that we will not describe any parallel asynchronous iterative methods that are sometimes proposed for solving such systems when they are very large, possibly distributed across several computers that are connected by means of a relatively slow network; cf. (Bahi et al. Parallel Iterative Algorithms, (2008), Bertsekas and Tsitsiklis, Parallel and Distributed Computation, (1989), Kollias et al. PARCO, (2005), Ishii and Tempo, IEEE Trans. Autom. Control, 55(9), (2010)[5, 6, 7, 8]).
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arXiv (Cornell University), Jun 11, 2006
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Scientific computation, Jul 26, 2015
Eigenvalue problems form the second most important class of problems in numerical linear algebra.
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Scientific Computation, 2015
The \(\varepsilon \)-pseudospectrum, \(\varLambda _{\varepsilon }(A)\), of a square matrix (pseud... more The \(\varepsilon \)-pseudospectrum, \(\varLambda _{\varepsilon }(A)\), of a square matrix (pseudospectrum for short) is the locus of eigenvalues of \(A+E\) for all possible E such that.
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Parallelism in Matrix Computations, 2015
One key idea when attempting to build algorithms for large scale matrix problems is to detect if ... more One key idea when attempting to build algorithms for large scale matrix problems is to detect if the matrix has special properties, possibly due to the characteristics of the application, that could be taken into account in order to design faster solution methods.
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Numerical Algorithms, 2013
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The estimation of the diagonal of the inverse of a symmetric matrix, A, is an important problem i... more The estimation of the diagonal of the inverse of a symmetric matrix, A, is an important problem in many applications. Following the statistical estimation approach of Hutschinson, several methods for this task (eg [1, 3]) depend on presence of an effective method for computing ζ A− 1ζ for a suite of suitably selected vectors ζ. Recently, some of these techniques were combined with conjugate gradients, iterative refinement and parallel processing to produce a method that for large matrices gave substantially better ...
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atlas-conferences.com
... for eigenvalue calculations NS Stylianopoulos Optimal Complex Semi-iterative Methods Applied ... more ... for eigenvalue calculations NS Stylianopoulos Optimal Complex Semi-iterative Methods Applied to SOR in the Case of Intersecting Lines Spectra Daniel B Szyld Algebraic Theory of Schwarz Methods for Domain Decomposition Panagiota Tsompanopoulou Analysis of an ...
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Parallel Computing, 2018
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Proceedings of the 1996 ICPP Workshop on Challenges for Parallel Processing, 2000
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Ics, 1987
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Papers by Efstratios Gallopoulos