Send mail to: mgnet@cs.yale.edu for the digests mgnet-requests@cs.yale.edu for comments or help Anonymous ftp repository: ftp.ccs.uky.edu (128.163.209.106) World Wide Web: http://www.mgnet.org or http://www.cerfacs.fr/~douglas/mgnet.html or http://phase.etl.go.jp/mgnet or http://www.ccs.uky.edu/mgnet Today's editor: Craig Douglas (douglas-craig@cs.yale.edu) Volume 8, Number 7 (approximately July 31, 1998) Today's topics: Important Date Postdoctoral Position MG Solver for 3D Cylindrical Domain Question Preprint by Mercier Preprint by Brenner and Sung Preprint by Carvalho, Giraud, and Le Tallec 2 Preprints by Bittencourt, Douglas, and Feijoo Copper Mountain Conference on Multigrid Methods First Southern Symposium on Computation GMD Multigrid Course ------------------------------------------------------- Date: Fri, 31 Jul 1998 18:12:37 -0400 From: Craig Douglas Subject: Important Date August 15 Abstracts for the Fourth IMACS International Symposium on Iterative Methods in Scientific Computation (celebrating David M. Young's 75th birthday), October 18-20, 1998 at the University of Texas, Austin, TX, USA. See http://www.ticam.utexas.edu/dmy98 or send e-mail to dmy98@ticam.utexas.edu for more information. ------------------------------------------------------- Date: Tue, 4 Aug 1998 14:58:51 -0400 (EDT) From: Jun Zhang Subject: Postdoctoral Position Postdoctoral Research Associate Position A postdoctoral research associate position is available in the Department of Computer Science of the University of Kentucky. This position is funded by the Center for Computational Sciences of the University of Kentucky. The position may start sometime after August 16, 1998. Research topics will generally be in applied scientific and parallel computing, those include but are not limited to multi-level or multigrid methods, robust preconditioning techniques, numerical solution of partial differential equations, computational fluid dynamics. (Check the URL address http://www.cs.uky.edu/~jzhang.) Programming skill (in Fortran or C) is essential and experience with parallel computers is desirable. Interested people should e-mail a curriculum vitae (with full publication list and e-mail addresses of three referees) in postscript or ASCII to Jun Zhang at jzhang@cs.uky.edu or fax it to (606)323-1971. The last means is to send a postal mail to: Professor Jun Zhang Department of Computer Science University of Kentucky 773 Anderson Hall Lexington, KY 40506--0046 Please do NOT have the reference letters sent, they will be requested if needed. ------------------------------------------------------- Date: Thu, 23 Jul 1998 10:24:41 +1000 (EST) From: Muhammad Ashraf To: Craig Douglas Subject: MG Solver for 3D Cylindrical Domain Question My problem is a coupled heat transfer and fluid flow in 3D circular cylinder. It uses the finite difference formulation of vorticity-vector potential equations. I used biconjugate gradient solver for three elliptic vector potential equations but it consumes more than 90% of the CPU time. I would appreciate some help to indicate a 3D MG solver for elliptic equations in cylindrical domain that a) accounts for singularity at the axis, b) had finite difference discretized domain and c) uses mixed Neuman-Dirichlet boundary conditions. Best regards and thanks Muhammad Ashraf School of Mechanical and Manufacturing Engineering The University of New South Wales Sydney 2052 Australia Email: ashraf@cfd.mech.unsw.edu.au Editor's Note: Please cc mgnet@cs.yale.edu if you respond to him. ------------- ------------------------------------------------------- Date: Thu, 11 Jun 1998 19:12:41 +0200 From: Jean-Marc Mercier Subject: Preprint from Mercier Note on a Multigrid Mesh Refinement Technique for Hyperbolic Problems J. M. Mercier S.I.S.S.A. 4 Via Beirut I-34014 Trieste, Italy mercier@sissa.it May 1998 Abstract: We present in this note a multi-dimensional mesh refinement technique that is adaptive both in time and space. This technique is based on the principle of maintaining a C.F.L. ratio constant throughout the time calculus and is designed in its actual form for schemes modeling hyperbolic problems. To test it, we study numerically two hyperbolic model problems in two dimensions of space. The first is an advection equation, the second is the free wave equation. The goal of these computations is to retrieve the results computed with the same numerical scheme and C.F.L. ratio over a regular space time grid of the thinner mesh used by our adaptive mesher. Editor's Note: This can be found through www.mgnet.org/mgnet-papers.html ------------- or mgnet/papers/Mercier/adapt.ps.gz. ------------------------------------------------------- Date: Fri, 31 Jul 1998 15:20:10 -0400 (EDT) From: Susanne Brenner Subject: Preprint by Brenner and Sung Our paper, "Lower bounds for two-level additive Schwarz preconditioners for nonconforming finite elements," which will appear in the proceedings of the Guangzhou International Symposium on Computational Mathematics is available as report 98:05 at http://www.math.sc.edu/~imip/98.html Sue Brenner and Li-yeng Sung ------------------------------------------------------- Subject: Preprint by Carvalho, Giraud, and Le Tallec Algebraic two-level preconditioners for the Schur complement method L. M. Carvalho CERFACS - France and COPPE-UFRJ Brazil carvalho@cos.ufrj.br L. Giraud CERFACS, 42 av.Gaspard Coriolis, 31057 Toulouse Cedex luc.giraud@cerfacs.fr P. Le Tallec CEREMADE, Universite Paris Dauphine, 75 775 Paris Cedex 16 CERFACS Technical Report TR/PA/98/18- June 1998 Abstract The solution of elliptic problems is challenging on parallel distributed memory computers as their Green's functions are global. To address this issue, we present a set of preconditioners for the Schur complement domain decomposition method. They implement a global coupling mechanism, through coarse space components, similar to the one proposed in [3]. The definition of the coarse space components is algebraic, they are defined using the mesh partitioning information and simple interpolation operators. These preconditioners are implemented on distributed memory computers without introducing any new global synchronization in the preconditioned conjugate gradient iteration. The numericaland parallel scalability of those preconditioners is illustrated on two-dimensionalmodel examples that have anisotropy and/or discontinuity phenomena. [3] J. H. Bramble, J. E. Pasciak, and A. H. Schatz. The construction of preconditioners for elliptic problems by substructuring I, Math. Comp., 47 (175): 103-134, 1986. Key words : Domain decomposition, two-level preconditioning, Schur complement, parallel distributed computing, elliptic partial differential equations. Editor's Note: Both can be found through www.mgnet.org/mgnet-papers.html ------------- or in mgnet/papers/Carvalho-Giraud-LeTallec/alg2lev.ps.gz. ------------------------------------------------------- Date: Tue, 4 Aug 1998 09:26:39 -0400 (EDT) From: Marco Bittencourt Subject: 2 Preprints by Bittencourt, Douglas, and Feijoo Non-nested and non-structured multigrid methods applied to elastic problems. Part I: The two-dimensional case Marco L. Bittencourt Center for Computational Sciences University of Kentucky 325 McVey Hall, Lexington, KY, 40506-0045, USA e-mail: mlb@ccs.uky.edu Craig C. Douglas Department of Mathematics University of Kentucky 715 Patterson Office Tower, Lexington, KY, 40506-0027, USA e-mail: douglas@ccs.uky.edu Raul A. Feijoo Laboratorio Nacional de Computacao Cientifica (LNCC/CNPq) Av. Getulio Vargas 333, CEP 25651-070, Petropolis/RJ, Brazil e-mail: feij@alpha.lncc.br Abstract This paper presents the application of non-nested and non-structured multigrid methods for two-dimensional elastic linear problems. Some basic aspects related to multigrid methods are discussed including nested iterations, coarse grid correction scheme, transfer operators, and multigrid strategies. A variational formulation for the transfer operators is also considered. The C++ implementation of the multigrid software is discussed and some examples are analyzed. The performance of multigrid strategies is compared with direct and pre-conditioned conjugate gradient algorithms. * * * * * Non-nested and non-structured multigrid methods applied to elastic problems. Part I: The three-dimensional case Marco L. Bittencourt Center for Computational Sciences University of Kentucky 325 McVey Hall, Lexington, KY, 40506-0045, USA e-mail: mlb@ccs.uky.edu Craig C. Douglas Department of Mathematics University of Kentucky 715 Patterson Office Tower, Lexington, KY, 40506-0027, USA e-mail: douglas@ccs.uky.edu Raul A. Feijoo Laboratorio Nacional de Computacao Cientifica (LNCC/CNPq) Av. Getulio Vargas 333, CEP 25651-070, Petropolis/RJ, Brazil e-mail: feij@alpha.lncc.br Abstract Aspects of non-nested and non-structured multigrid methods with applications to two-dimensional elastic problems were presented in a companion paper by the current authors, Non-Nested and Non-Structured Multigrid Methods Applied to Elastic Problems, Part I: The Two-Dimensional Case. In this paper a review of some multigrid strategies, procedures for geometric search to implement transfer operators, expressions for calculating the number of operations and memory space, and aspects of convergence are presented. Three-dimensional elastic problems are solved by multigrid, sparse Gaussian elimination, and conjugate gradient methods. The number of operations and memory requirements are compared. Editor's Note: Both can be found through www.mgnet.org/mgnet-papers.html ------------- or mgnet/papers/Bittencourt-Douglas-Feijoo/paper{1,2}.ps.gz. ------------------------------------------------------- Date: Wed, 15 Jul 1998 14:00:42 -0600 (MDT) From: Steve McCormick Subject: Copper Mountain Conference on Multigrid Methods ANNOUNCING: Ninth Copper Mountain Conference on Multigrid Methods April 11-16, 1999 Copper Mountain, Colorado, USA ORGANIZED BY: The University of Colorado The Society for Industrial and Applied Mathematics The Center for Advanced Scientific Computation at LLNL The Institute for Algorithms and Scientific Computing of the GMD Front Range Scientific Computations, Inc. TENATIVE SPONSORS: DOE, NSF, and IBM THEME: GENERAL SCALABLE MULTIGRID METHODS: ALGEBRAIC AND PARALLEL TECHNIQUES. Every effort will be made to encourage contributions from anyone whose interest lies in these important and rapidly evolving fields. IMPORTANT FEATURES: STUDENT PAPER COMPETITION. We are hoping to support the participation of several students, depending on availability of grant funds. MULTIGRID TUTORIAL. We will offer an updated tutorial on basic multigrid and advanced multilevel techniques, including algebraic multigrid (AMG). CONFERENCE DEADLINES: Student Papers Dec. 15, 1998 Author Abstracts Feb. 1, 1999 Early Registration Feb. 1, 1999 FURTHER INFORMATION: Please access our web site at http://amath-www.colorado.edu/appm/faculty/copper or contact Cathy Lee FRSC 1390 Claremont Drive Boulder, CO 80303 USA (303) 554-1232 copper@boulder.colorado.edu ------------------------------------------------------- Date: Wed, 8 Jul 1998 10:30:01 -0500 (CDT) From: Jiangping Zhu Subject: First Southern Symposium on Computation PRELIMINARY CALL FOR CONTRIBUTIONS FIRST SOUTHERN SYMPOSIUM ON COMPUTATION December 4-5, 1998 University of Southern Mississippi Hattiesburg, Mississippi Organized by: School of Mathematical Sciences of the University of Southern Mississippi in cooperation with the Department of Mathematics and Statistics and the Department of Computer Science, Mississippi State University, Department of Computer Science, Louisiana State University The aim of the conference is to bring together researchers in ALL areas of computation and in an informal atmosphere attempt to develop links between its various threads. KEYNOTE ADDRESSESS (preliminary list): G. Fairweather (Colorado School of Mines) - tentative S. Iengar (Louisiana State University) P. Lax (Courant Institute) - tentative S. Piacsek (Stennis Space Center) T. Skjellum (Mississippi State University) L. Welch (UT Arlington) - tentative J. Zhu (Mississippi State University) PROGRAM COMMITTEE: I. Banicescu (Mississippi State University, USA) V. Berinde (North University of Baia Mare, Romania) I. Bar-On (Technion University, Israel) A. Al-Dhelaan (King Saud University, Saudi Arabia) A. Blazhievskiy (University of Podillia, Ukraine) C. Breshears (Waterways Experiment Station MSRC, Vicksburg, USA) I. Gladwell (Southern Methodist University, USA) J. Leszczynski (Jackson State University, USA) X. Li (Loyola University, New Orleans, USA) N. Mastorakis (Hellenic Naval Academy, Greece) F. Mazzia (University of Bari, Italy) P. Schmidt (University of Akron, USA) I. Sivergina (Jekaterinburg Tech, Russia) T. Taha (University of Georgia, USA) J. Tyler (Louisiana State University, USA) P. Yalamov (University of Rousse, Bulgaria) W. Zhang (Louisiana Tech, USA) B. Zubik-Kowal (University of Leiden, Netherlands) Organizing Committee: M. Paprzycki (Chair) A. Ali, C. Burgess, M. Cobb, J. Ding, J. Kolibal, J. Lee, M. Mascagni, R. Necaise, R. Pandey, W. Russell and R. Seyfarth. We invite contributions covering all areas of computation. Special sessions are also welcome. Contributions from graduate students are also invited. IMPORTANT DATES: Special session proposals due: September 30, 1998 Extended abstracts (1 page) due: October 31, 1998 Acceptance: November 15, 1998 Papers for proceedings: November 30, 1998 Electronic proceedings will be published. Information about the meeting will be updated on the conference WWW site to be located at: http://pax.st.usm.edu/cmi/fscc98.html To obtain more information about the meeting send e-mail to: fscc98@pax.st.usm.edu ------------------------------------------------------- Date: Thu, 30 Jul 1998 09:50:19 +0200 (MDT) From: Wolfgang Joppich Subject: Multigrid Course Dear Ladies and Gentlemen, dear colleagues and friends! Let me first apologize if this message disturbs you. I don't want to inconvenience you. Nevertheless, I want to attract your attention to a MULTIGRID COURSE at the GMD from Friday 20.11.1998 to Sunday 22.11.1998. For more information contact joppich@gmd.de or look at the GMD web pages http://www.gmd.de, click welcome to GMD and go to events. You may also view directly http://www.gmd.de/SCAI/scicomp/multigrid98.html If you know anyone who might be interested in such a course, please inform them. Thank you for your help. With kind regards Wolfgang Joppich, GMD-SCAI ------------------------------ End of MGNet Digest **************************