NA Digest Saturday, October 30, 1999 Volume 99 : Issue 43 Today's Editor: Cleve Moler The MathWorks, Inc. moler@mathworks.com Today's Topics: * Rounding Error * Re: Difference Between 1x1 Matrices and Scalars * New Journal, Nonlinear Sciences and Numerical Simulation * NICONET E-letter * NSF's Information Technology Research Program * Change of Address for T. Terlaky * Conference in Honor of Burton Wendroff * NICONET Workshop * SIAM Conference on Materials Science * Workshop on Numerical Methods for Kinetic and Hyperbolic Equations * ACM 2000 Java Grande Conference * Australian and New Zealand Industrial and Applied Mathematics Society * Congress on Computational and Applied Mathematics * Symposium on Symbolic and Algebraic Computation * Special Issue on Parallel and Distributed Simulation * Volume Dedicated to Prof. Galligani * Faculty Position at University of Illinois at Chicago * Research Positions Stiftung Caesar, Bonn * Visiting Faculty Positions at Worcester Polytechnic Institute * Research and Development Position at Wolfram Research * Student Position at Delft University of Technology * Postdoctoral Positions at University of Delaware * Faculty Positions at Penn State University * Postdoctoral Positions at Lawrence Berkeley National Laboratory * Postdoctoral Positions in The Netherlands * Contents, Reliable Computing Submissions for NA Digest: Mail to na.digest@na-net.ornl.gov. Information about NA-NET: Mail to na.help@na-net.ornl.gov. URL for the World Wide Web: http://www.netlib.org/na-net/na_home.html ------------------------------------------------------- From: G. W. Stewart Date: Mon, 25 Oct 1999 14:55:57 -0400 (EDT) Subject: Rounding Error On October 11, I posted the following query in the NA Digest. I'm giving a talk later this month on rounding error to the Baltimore-Washington Section of SIAM. I would appreciate any interesting anecdotes on real-life embarrassments due to rounding error. I recall (though I don't know the details) stories about an index on the Canadian stock market drifting off true and something about a missile in the Iraq war. If you know the details of these or any other stories, please pass them on to me. Pete Stewart The response was certainly gratifying. Within two days I received 64 messages. They were a great help in preparing my talk, which I gave on October 20 at Johns Hopkins. My thanks to everyone. (For those who are interested, a postscript file of my transparencies can be found at ftp://thales.cs.umd.edu/pub/misc/roundtalk.ps) I was surprised to find how few incidents were reported. Apparently, with some notable exceptions, the problems due to roundoff are themselves at the level of roundoff. Many responders asked me to post a summary. Here is a list of the incidents I used in my talk with references and a brief description. 1. The Patriot and the Scud. Sources 1. General Accounting Office Report GAO/IMTEC-92-26. 2. Robert Skeel, "Roundoff Error Cripples Patriot Missile," SIAM News, July 1992. On February 25, 1991, during the Gulf War, a Patriot missile defense system let a Scud get through. It hit a barracks, killing 28 people. The problem was in the differencing of floating point numbers obtained by converting and scaling an integer timing register. The GAO report has less than the full story. For that see Skeel's excellent article. 2. The short flight of the Ariane 5. Source 1. Report by the Inquiry Board. http://www.esrin.esa.it/htdocs/tidc/Press/Press96/ariane5rep.html On June 4, 1996, the first Ariane 5 was launched. All went well for 36 seconds. Then the Ariane veered off course and self-destructed. The problem was in the Inertial Reference System, which produced an operation exception trying to convert a 64-bit floating-point number to a 12-bit integer. It sent a diagnostic word to the On-Board Computer, which interpreted it as flight data. Finis. Ironically, the computation was done by legacy software from the Ariane 4, and its results were not needed after lift-off. 3. The Vancouver Stock Exchange Sources 1. The Wall Street Journal November 8, 1983, p.37. 2. The Toronto Star, November 19, 1983. 3. B.D. McCullough and H.D. Vinod Journal of Economic Literature Vol XXXVII (June 1999), pp. 633-665. (References communicated by Valerie Fraysse) In 1982 (I figure) the Vancouver Stock Exchange instituted a new index initialized to a value of 1000.000. The index was updated after each transaction. Twenty two months later it had fallen to 520. The cause was that the updated value was truncated rather than rounded. The rounded calculation gave a value of 1098.892. 4. Parliamentary elections in Schleswig-Holstein. Sources 1. Rounding error changes Parliament makeup Debora Weber-Wulff The Risks Digest Volume 13, Issue 37, 1992 http://catless.ncl.ac.uk/Risks/ In German parliamentary elections, a party with less than 5.0% of the vote cannot be seated. The Greens appeared to have a cliff-hanging 5.0%, until it was discovered (after the results had been announced) that they really had only 4.97%. The printout was to two figures, and the actual percentage was rounded to 5.0%. 5. For a few more examples try searching the RISK Digest (http://catless.ncl.ac.uk/Risks/) with the key word "rounding" (David Goldberg's idea). Once again, thanks to all of you for your help. Pete Stewart ------------------------------ From: Mike Hosea Ross Lippert Miguel Sousa Lobo Date: Mon, 25 Oct 1999 00:18:15 -0500 Subject: Re: Difference Between 1x1 Matrices and Scalars Ilse Ipsen wrote: - Consider the matrix product A*B*C where - - A = [1 1] B = [1] C=[1] - [1] [2] - [3] - - The product A*B*C is not defined because B*C is not defined. - Nevertheless MATLAB 5.3 computes the answer [2] - [4] - [6] - - presumably because it associates (A*B)*C. In this case A*B - happens to be a scalar but should be treated as a 1x1 matrix. - - Is this something to worry about? Mike Hosea responds: I agree mostly with what other respondents have been saying, but they have left me somewhat perplexed by leaping to conclusions of what should be done about this problem. Unless I missed it, nobody as yet has mentioned what it would cost to impose formal correctness in this matter, nor has much been said about the ultimate consequences of not doing so. So, let's consider it. First, what happens to us if it is not fixed. Well, it has been established that Matlab will allow some constructs that aren't formally correct. Okay, but is this really a problem? Matlab 5.3 behavior in this regard is not new, and the software has long proven its usefulness. If the alternative is to issue an error, I must wonder how this error message would add to the usefulness of the software. Matlab is not an environment for validating symbolic mathematics, and the lack of errors from any number-crunching environment is hardly convincing evidence of the validity of the mathematics behind what is being computed. If the manifestations of the problem are limited to instances where Matlab should have issued an error but didn't, and hence returned some results in accordance with a certain interpretation instead of issuing no results at all, then I do not see that the current behavior has any significant negative impact, at least of a practical nature. Second, what happens to us if it is fixed. Well, it is common enough in mathematical papers to equivocate n x 1 (and sometimes 1 x n) matrices with n-vectors, and it is likewise common to regard the matrix product of x' and y, where x and y are n x 1 matrices, as a handy way of representing the dot product. This avoids the need to define a formal transformation from the set of n x 1 matrices to the set of n-vectors and to use it every time one wants to do a dot product (or, perhaps, to use its inverse when one wants to do a matrix product). For example, almost any treatise on numeric eigenvalue computation or nonlinear optimization will contain equations like "alpha = (x'Ay)/(x'y)". This is not done because the writers are unaware of the formal distinction between a 1x1 matrix and a scalar. It is done because it is convenient, and everybody knows what the writers mean. To do otherwise would rightly be regarded as pedantic. The equivalence of scalars and 1x1 matrices in Matlab certainly helps here, and I am certain that Matlab users have taken advantage of it for a long time, often eschewing dot(x,y) in favor of x'*y because it more closely approximates the form of the expression they are trying to represent in Matlab's language. I would not be surprised to hear that the current behavior was designed to support this inclination, and I shudder to think of all the programs that would break if Matlab were to start issuing error messages in this case. From a pedagogical perspective, we should indeed worry about such things. Students are often confused enough as it is, and for teaching purposes in elementary linear algebra, I might prefer an environment that is quite a bit more rigid and pedantic than Matlab. From a practical perspective, however, changing Matlab behavior in this matter is likely to cause a lot of problems for existing Matlab programs in exchange for next to no benefit. ************ Ross Lippert responds: OK, here are 2 cents from a fan of lex and yacc. This all comes down to the parsing of a*b*c. Treating MATLAB as a formal grammar following rules like expr--> expr * expr | variable | literal | .... we find that a*b*c is ambiguous, in the sense that is can be generated by the two different sequences expr --> expr*expr --> a*expr --> a*expr*expr --> a*b*c = a*(b*c) expr --> expr*expr --> expr*c --> expr*expr*c --> a*b*c = (a*b)*c This is not new to MATLAB or any other language that has a comfortable artihmetic syntax. We like and use ambiguous grammars likes this in C, fortran, whathaveyou. The way the ambiguity gets resolved in such languages is by the use of associativity rules in the parser. If * is right associative we do the first sequence, always. If left, we take the second. My first cent: This "bug" is nothing new The associativity of an operator can have observable consequences without the use of matrices. For example, let >> x = -1; y = 1+eps; z = 1; >> x+y+z == 1 returns 'true' is + is parsed as left associative and 'false' is + is right associative. Thus, this sort of trouble has been with us before we had fancy Matrix language interpreters. It has to do with operators more than with matrices. Just as one can generate statements which will raise error messages if parsed with a different associativity with matrices, so can one do the same with mere scalars. My second cent: This "bug" requires documentation Assuming that this discussion would not be taking place, if the associativity of the MATLAB operators was not explicitly described somewhere in official MATLAB documentation, here is why I think that it should be documented clearly. Some languages, (C, but not Fortran) do not have specified associativities with operators and, under "-O" conditions, sometimes will reassociate expressions. This can have some unfortunate consequences for scalar expressions, but even more unfortunate consequences for matrix expressions. So, someone writing a MATLAB parser (syntax checker, clone, MATLAB to C converter, MATLAB compiler, etc), who does not know what the associativity of each operator is, might guess left associative (and most people do) and get it right, or guess right associative, or reassociate in an optimization step, and thereby produce bizarre errors in their result. If the associativity of the operators is left undocumented, then statements such as A*B*C should be considered machine/version dependent, and, as the version/dependent syntaxes of MATLAB do, should generate a warning. ************ Miguel Sousa Lobo responds: Yet one more comment about matrix multiplication in Matlab. All this discussion would become pointless if The Mathworks added a line to its documentation saying: "By default, multiplication in Matlab is associated left to right (and parsed accordingly.)" This is Matlab's current (and perfectly defensible) behavior. Best regards, Miguel ------------------------------ From: Wen Chen Date: Mon, 25 Oct 1999 10:54:55 +0900 Subject: New Journal, Nonlinear Sciences and Numerical Simulation Dear Colleagues: A new "international journal of Nonlinear Sciences and Numerical Simulation" will be launched in the coming 2000 year. The sponsorships of institutes and universities worldwide are invited to join in us to activate the nonlinear sciences. The nomination of member of editorial board is also welcome. Aims and Scope of this journal is given below The International Journal of Nonlinear Sciences and Numerical Simulation publishes original papers on all subjects relevant to nonlinear sciences and numerical simulation. The highest priority will be given to those contributions concerned with a discussion of the background of a practical problem, the establishment of an appropriate nonlinear model, the determination of a solution, approximate or exact, analytical or numerical, and a discussion of the relevance of the results when applied to the real-life problem. The following types of manuscript are encouraged: 1) New nonlinear model for a real-life problem with possible exciting applications; 2) New analytical techniques for new nonlinear problems with physical understanding; 3) Numerical simulation revealing possible hidden pearls in nonlinear sciences. Although the journal concentrates mainly on the applications side, review articles dealing with establishment of nonlinear models, new numerical or analytical techniques, with potential for wider application to real-life problems, are invited by the Editor, and will be published from time to time. For more details please contact Editor-in-Chief Dr. Ji-Huan He 149 Yanchang Road, Shanghai University, Shanghai Institute of Applied Mathematics and Mechanics, Shanghai 200072, China. Yours sincerely, W. CHEN ------------------------------ From: A.J.W.v.d. Boom Date: Mon, 25 Oct 1999 14:33:25 +0200 Subject: NICONET E-letter The fifth issue of the NICONET E-letter is now available and can be accessed from the World Wide Web URL: http://www.win.tue.nl/wgs/E-letter.html or can be downloaded as compressed postscript file from the WGS ftp site: ftp://wgs.esat.kuleuven.ac.be/pub/wgs/E-LETTER ( filename: E-issue-5.Z) Contents: 1. Welcome to the NICONET E-letter number 5 2. New additions to SLICOT since July 1999 3. New NICONET Reports since July 1999 4. Niconet events 5. (Forthcoming) Meetings and symposia attended by NICONET partners ------------------------------ From: Kamal Abdali Date: Mon, 25 Oct 1999 09:56:59 -0400 Subject: NSF's Information Technology Research Program The National Science Foundations's newly announced Information Technology Research (ITR) program should be of interest to the scientific computing/computational science research community. There is a web site http://www.itr.nsf.gov that includes the program announcement, various information items, and a FAQ. The ITR program has been developed in response to the President's Information Technology Advisory Committee (PITAC) Report to the President. The report, entitled "Information Technology Research: Investing in Our Future" http://www.ccic.gov/ac/report , contains a number of findings and recommendations. High end computing is one of the Technical Research priorities in the report. The high-end computing research recommended by PITAC is covered in, among other places, the section entitled "Advanced Computational Science" in the ITR announcement. This section invites proposals for leading-edge research in algorithms, software and systems that is applicable to scientific and engineering computation. The list of research topics explicitly mentioned in this section include: numerical methods, optimization, symbolic and algebraic computation, computational geometry, software libraries, problem-solving environments, computer graphics and scientific visualization. ------------------------------ From: T. Terlaky Date: Fri, 29 Oct 1999 14:57:03 -0400 Subject: Change of Address for T. Terlaky My new address is: Prof. Tam=E1s Terlaky Office: JHE/214 Department of Computing and Software McMaster University Hamilton, Ontario, Canada, L8S 4L7 Phone: (905) 525-9140 ext. 27780 Fax: (905) 524-0340 Email: terlaky@cas.mcmaster.ca www: http://www.cas.mcmaster.ca/~terlaky ------------------------------ From: Mikhail Shashkov Date: Tue, 26 Oct 1999 11:10:40 -0600 (MDT) Subject: Conference in Honor of Burton Wendroff CONFERENCE ON SYSTEMS OF CONSERVATION LAWS AND RELATED TOPICS To honor BURTON WENDROFF on the occasion of his 70-th Birthday. March 8-10, 2000 Los Alamos National Laboratory Los Alamos, New Mexico, USA http://www-troja.fjfi.cvut.cz/~liska/bbw/ The main theme of this conference will be the numerical solution of systems of conservation laws but other areas of importance for scientific computing will also be addressed. A PRELIMINARY PROGRAM March 8, 2000, Wed. Stan Osher "From Lax-Wendroff to TVD, ENO, WENO, Level Set Methods, Ghost Fluids & Back Again" Pete Miller "Computational Transport Theory in the Early Days: Wendroff's Contributions" Herb Keller A Rank Theory of DAE's. W.J. Rider and L.G. Margolin "Entropy Consistency through Nonlinear Dispersion" Seymour Parter "Preconditioning Spectral Collocation Methods for Elliptic Problems" Vidar Thomee "Maximum-norm Estimates for Parabolic Finite Element Equations" "Stable Schemes for Evolving Half-Space with General Boundary Conditions" Reuben Hersh "Stable Schemes for Evolving Half-Space with General Boundary Conditions" March 9, 2000, Thursday. P. Lax - TBA Herb Kranzer "Nonstrictly Hyperbolic Conservation Laws and Singular Shocks" Joel Smoller "Cosmology with a shock-wave" Mac Hyman "High-Order Predictor-Corrector Methods for Conservation Laws" Blair Swartz "Swiftly slicing specific fractions from n bodies in n-space" Richard Liska "Composite Schemes for Conservation Laws" Randy LeVeque "Three-dimensional wave-propagation algorithms for hyperbolic systems: some upwinded and limited variants of Lax-Wendroff" Jerry Brackbill "The Immersed boundary Method: Some successes and Challenges" March 10, 2000, Friday. Eitan Tadmor "Central Schemes: Convergence and Error Estimate for High Resolution Methods" H. Bruce Stewart "The Virtues of a Computational Toolkit for Dynamical Systems" Heinz Kreiss "The numerical solution of nonlinear time dependent partial differential equations" Norman Bleistein "High Frequency Imaging: from String Contruction to Micro-Local Analysis" Bill Morton "Vorticity-preserving Lax-Wendroff Schemes on Arbitrary Meshes" Mikhail Shashkov "Discrete Vector Analysis" Len Margolin and P.K. Smolarkiewicz "Turbulence Modeling Using Nonoscillatory Lax-Wendroff Methods" Sessions for contributed papers are not planned at this time, but all who are interested are welcome to attend. For additional information about this conference, please visit the conference web page http://www-troja.fjfi.cvut.cz/~liska/bbw/ or contact Dr. Mikhail Shashkov MS-B284, Group T-7, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA, 87545 e-mail:misha@t7.lanl.gov ------------------------------ From: A.J.W.v.d. Boom Date: Wed, 27 Oct 1999 11:04:51 +0200 Subject: NICONET Workshop Second NICONET workshop December 3, 1999 The Second NICONET workshop will be held at INRIA Rocquencourt, France. The workshop is sponsored by the EU. The workshop covers all aspects of numerical software in systems and control and their implementation and use in industrial practice. See the NICONET website at: http://www.win.tue.nl/niconet for more details. Workshop secretariat: Mrs. Christine Bren Fax: + 33-1-39635638 Mail: INRIA, Relations Exterieures Domaine de Voluceau Rocquencourt B.P. 105 78153 Le CHESNAY CEDEX (FRANCE) WWW: http://www-rocq.inria.fr/Niconet/register.html e-mail: symposia@inria.fr ------------------------------ From: Trini Flores Date: Thu, 28 Oct 1999 09:41:08 -0500 Subject: SIAM Conference on Materials Science Third SIAM Conference on Mathematical Aspects of MATERIALS SCIENCE May 21-24, 2000 Crowne Plaza Hotel Philadelphia, Pennsylvania NOVEMBER 15, 1999 -- Deadline for submission of minisymposium proposals. For information on how to submit, please visit www.siam.org/meetings/ms00/ or send e-mail to meetings@siam.org ------------------------------ From: Workshop Date: Thu, 28 Oct 1999 18:04:46 +0200 (MET DST) Subject: Workshop on Numerical Methods for Kinetic and Hyperbolic Equations Workshop on NUMERICAL METHODS FOR KINETIC AND HYPERBOLIC EQUATIONS Ferrara, Italy, December 17-18, 1999 Location: Department of Mathematics, University of Ferrara Via Machiavelli, 35 I-44100 Ferrara, Italy Organizers: L. Pareschi (University of Ferrara), V. Ruggiero (University of Ferrara), G. Toscani (University of Pavia), R. Natalini (IAC, Rome). The workshop is organized jointly with the TMR projects "Asymptotic methods in kinetic theory" and "Hyperbolic systems of conservation laws" and is partially supported by MURST, Progetto Nazionale di Ricerca "Analisi numerica: metodi e software scientifico". Topics will include: - Deterministic and Monte Carlo methods for kinetic equations - Multiscale hyperbolic and kinetic problems - Hyperbolic relaxation approximations - High order methods for conservation laws List of speakers: S. Jin (Atlanta), R. Natalini (Rome), G. Russo (L'Aquila), D. Aregba Driollet (Bordeaux), C. Buet (Paris), S. Cordier (Paris), M. Falcone (Rome), F. Filbet (Nancy), A. Frezzotti (Milano), I. Ibragimov (Saarbrucken), A. Klar (Berlin), M. Lemou (Toulose), L. Mieussens (Bordeaux), G. Naldi (Milano), G. Puppo (Torino), S. Rjasanow (Saarbrucken), V. Romano (Bari), C. Schmeiser (Vienna), B. Wennberg (Goteborg). Contact: For further information consult the web page http://dm.unife.it/~numhk For registration write a message with your data (name, university or institute, address etc.) to numhk@dm.unife.it ------------------------------ From: Michael Philippsen Date: Thu, 28 Oct 1999 12:08:41 +0200 Subject: ACM 2000 Java Grande Conference CALL FOR PAPERS ACM 2000 Java Grande Conference Sponsored by ACM SIGPLAN San Francisco, California, June 3-4, 2000 http://www.extreme.indiana.edu/java00 The Java Grande Conference focuses on the use of Java in the broad area of high-performance computing; including engineering and scientific applications, simulations, data-intensive applications, and other emerging application areas that exploit parallel and distributed computing or combine communication and computing. A day of tutorials will be held on the day following the conference. The conference precedes the JavaOne 2000 conference, which would enable the Java Grande attendees to expose themselves to the latest in basic Java Technology. Authors are invited to submit manuscripts that demonstrate timely results, technologies, or experiences that are most likely to have impact on the use of Java in high performance computing systems. Topics of interest include but are not restricted to: Java use for scientific and engineering applications Java frameworks and libraries for high-performance computing Implementation techniques for Java on high-performance systems Java numerics and Java extensions for high-performance computing Java compilation and optimization for high-performance computing Java development tools and environments for high-performance computing Java performance and benchmarking CONFERENCE CHAIR Dennis Gannon Department of Computer Science Indiana University Bloomington, IN 47401 and NAS Division NASA Ames Research Center MS 258-5 Moffet Field, CA 94035 Phone: (650) 604 1934 gannon@cs.indiana.edu PROGRAM CHAIR Piyush Mehrotra ICASE MS 132C 3 West Reid Street - Building 1152 NASA Langley Research Center Hampton, VA 23681 Phone: (757)-864-2188 Fax: (757)-864-6134 pm@icase.edu PROGRAM COMMITTEE Henri Bal, Vrije University Sandra Baylor, IBM Aart Bik, Intel Corporation Siddartha Chatterjee, University of North Carolina Ken Kennedy, Rice University Scott Kohn, Lawrence Livermore National Laboratory Arvind Krishnamurthy, Yale University Timothy Lindohm, Sun Microsystems Satoshi Matsuoka, Tokyo Institute of Technology Roldan Pozo, NIST Vivek Sarkar, IBM Suresh Srinivas, SGI Vaidy Sunderam, Emory University Gregor von Laszewzki, Argonne National Laboratory Martin Westhead, EPCC Kathy Yelick, University of California at Berkeley PUBLICITY CHAIR Michael Philippsen Computer Science Department University of Karlsruhe Am Fasanengarten 5 76128 Karlsruhe Germany Phone: 49-721-608-4067 Fax: 49-721-608-7343 phlipp@ira.uka.de ------------------------------ From: Andy Philpott Date: Fri, 29 Oct 1999 13:20:28 +1300 Subject: Australian and New Zealand Industrial and Applied Mathematics Society ANZIAM 2000 ANZIAM is the Australian and New Zealand Industrial and Applied Mathematics Society. The 36th Annual Applied Mathematics Conference and Annual Meeting of ANZIAM will be held at the Copthorne Resort in Waitangi on the shores of the Bay of Islands, New Zealand, from the evening of Tuesday 8 February 2000 to lunchtime on the following Saturday 12 February. The annual conference of ANZIAM is an established gathering of applied mathematicians, scientists and engineers with wide-ranging interests. It provides an interactive forum for presentation of results and discussions by students, academics and other researchers on applied and industrial problems derived in many scientific fields and amenable to quantitative description and solution. The invited speakers are: Professor Jerzy Filar, University of South Australia Dr Derek Goring, National Institute of Water and Atmospheric Research, NZ Professor Peter Hunter, Auckland University Professor Peter Jackson, Auckland University Professor Nancy Kopell, Boston University Dr Margaret Wright, AT&T Bell Laboratories Further information and registration forms are available from the web page: http://www.esc.auckland.ac.nz/Organisations/anziam2000 or e-mail anziam2000@auckland.ac.nz ------------------------------ From: Luc Wuytack Date: Fri, 29 Oct 1999 09:20:55 +0200 (MET DST) Subject: Congress on Computational and Applied Mathematics ICCAM-2000 An International congress on Computational and Applied Mathematics will be organized on July 17-July 21, 2000 at the University of Leuven, Belgium. The congress will bring together people working on the analysis and application of computational techniques for solving real scientific problems. The list of invited speakers includes: Baker C.T.H. (U.K.), van Dooren P. (Belgium), Pryce J.D. (U.K.), Watson L.T. (USA), Sloan D. (U.K.), Brezinski C. (France), Yamamoto T. (Japan), Meek D.S. (Canada). Short communications will be accepted for presentation. An abstract of at most 1 page should be sent before March 30, 2000 to: Prof. M. Goovaerts, K.U. Leuven CRIR, Minderbroederstraat 5, B-3000 Leuven (Belgium) e-mail: Marc.Goovaerts@econ.kuleuven.ac.be ICCAM-2000 will also concentrate on the project "Numerical Analysis in the 20th century". Several survey talks will be given covering different fields of numerical analysis. The Proceedings of ICCAM-2000 will be published in the Journal on Computational and Applied Mathematics. More information can found at: http:/www.cs.kuleuven.ac.be/conference/iccam2000/iccam.htm ------------------------------ From: Paulina Chin Date: Fri, 29 Oct 1999 13:21:13 -0400 (EDT) Subject: Symposium on Symbolic and Algebraic Computation ANNOUNCEMENT AND CALL FOR PAPERS ISSAC 2000 International Symposium on Symbolic and Algebraic Computation St Andrews University, Scotland, August 7-9, 2000 http://www-gap.dcs.st-and.ac.uk/issac2000 ACM sponsorship pending ISSAC provides an opportunity to learn of new developments and to present original research in all areas of symbolic and algebraic computation. ISSAC 2000 will be held at St Andrews University, Scotland's oldest university. Planned activities include invited presentations, research and survey papers, poster sessions, tutorial courses, vendor exhibits and software demonstrations. CONFERENCE TOPICS Topics of the meeting include, but are not limited to: Algorithmic mathematics: Algebraic, symbolic, and symbolic-numeric algorithms including: simplification, polynomial and rational function manipulations, algebraic equations, summation and recurrence equations, integration and differential equations, linear algebra, number theory, group computations, and geometric computing; Computer sciences: Theoretical and practical problems in symbolic mathematical manipulation including: computer algebra systems, data structures, computational complexity, problem solving environments, programming languages and libraries for symbolic-numeric-geometric computation, user interfaces, visualization, software architectures, parallel or distributed computing, mapping algorithms to architectures, analysis and benchmarking, automatic differentiation and code generation, automatic theorem proving, mathematical data exchange protocols; Applications: Problem treatments incorporating algebraic, symbolic, symbolic-numeric and geometric computation in an essential or novel way, including engineering, economics and finance, architecture, physical and biological sciences, computer sciences, logic, mathematics, statistics, and uses in education. CALL FOR PAPERS Research results and insightful analyses of current concerns are the primary focus. Papers will be reviewed by the Program Committee and additional referees. Survey articles may be suitable for submission, if clearly identified as such, and will be considered in a separate category from the research papers. Simultaneous submission for publication elsewhere is not allowed. Authors are invited to submit papers to the Program Committee Chair before December 17, 1999. Submission instructions can be obtained from the conference Web page or by sending e-mail to bajaj@cs.utexas.edu. A poster session will be organized separately. Information is available on the conference Web site. FURTHER INFORMATION For more information, please refer to the conference Web page, http://www-gap.dcs.st-and.ac.uk/issac2000. E-mail inquiries may be sent to issac2000@dcs.st-and.ac.uk or to one of the conference committee members listed below: General Chair: Tomas Recio, recio@matesco.unican.es Local Arrangements Chair: Steve Linton, sal@dcs.st-and.ac.uk Program Committee Chair: Chandrajit Bajaj, bajaj@cs.utexas.edu Tutorial Chair: Josef Schicho, josef.schicho@risc.uni-linz.ac.at Exhibitor Chair: Marc Moreno Maza, Numerical Algorithms Group, marc@nag.co.uk Poster Session Chair: Arjeh Cohen, amc@win.tue.nl Editor: Carlo Traverso, traverso@posso.dm.unipi.it Treasurer: Colin Campbell, cmc@st-andrews.ac.uk Publicity Chair: Paulina Chin, pchin@wlu.ca ------------------------------ From: Marcin Paprzycki Date: Fri, 29 Oct 1999 23:56:25 -0500 (CDT) Subject: Special Issue on Parallel and Distributed Simulation Hi, this message is to remind everyone whois interested in contributing to the Special Issue of the PDCP Journal (http://orca.st.usm.edu/pdcp): ADVANCES IN PARALLEL AND DISTRIBUTED SIMULATION edited by: Carl Tropper, McGill University that the submission deadline is DECEMBER 15th, 1999. More details about the special issue and the journal can be found on the PDCP WWW site. All the best, Marcin Paprzycki phone: 601-266-6639 Department of Computer Science and Statistics or: 601-266-4949 University of Southern Mississippi Hattiesburg, MS 39406-5106, USA FAX: 601-266-6452 ------------------------------ From: Marcin Paprzycki Date: Sat, 30 Oct 1999 00:00:13 -0500 (CDT) Subject: Volume Dedicated to Prof. Galligani Hello! This messge is to remind everyone interested in contributing to the volume: RECENT TRENDS IN NUMERICAL ANALYSIS (volume intended to celebrate the 65-th birthday of Ilio Galligani) Edited by L. Brugnano and D. Trigiante, University of Florence, Italy that the submission deadline is NOVEMBER 15th. More information about the volume and the book series that it will be published in can be found no the http://orca.st.usm.edu/actp www site. Regards, Marcin Paprzycki phone: 601-266-6639 Department of Computer Science and Statistics or: 601-266-4949 University of Southern Mississippi Hattiesburg, MS 39406-5106, USA FAX: 601-266-6452 ------------------------------ From: Floyd Hanson Date: Mon, 25 Oct 1999 00:47:48 -0500 Subject: Faculty Position at University of Illinois at Chicago The Department has active research programs in all areas of pure mathematics, computational and applied mathematics, combinatorics and computer science, statistics, and mathematics education. See http://www.math.uic.edu for more information. Applications are invited for a tenure track or tenured position, effective August 21, 2000, in Computer Science, broadly defined. Current areas of interest include algorithms, coding theory, combinatorial optimization, combinatorics, complexity, computational mathematics, computational statistics, cryptography, data mining, graph theory, language design, learning theory, logic, numerical analysis, and universal algebra. The position is initially budgeted at the Assistant Professor level, but candidates with a sufficiently outstanding research record may be considered at higher levels. Applicants must have a Ph.D. or equivalent degree in mathematics, computer science, or a related field, an outstanding research record, and evidence of strong teaching ability, with particular interest in programming and algorithms. Salary negotiable. Send vita and direct 3 letters of recommendation, indicating the position being applied for, to Henri Gillet, Head; Dept. of Mathematics, Statistics, and Computer Science; University of Illinois at Chicago; 851 S. Morgan (M/C 249); Chicago, IL 60607. No e-mail applications will be accepted. To ensure full consideration, materials must be received by December 21, 1999. Minorities, persons with disabilities, and women are particularly encouraged to apply. UIC is an AA/EOE. For more information about the position or institution/company: http://www.math.uic.edu Deadline for Applications: December 21, 1999 ------------------------------ From: Axel Voigt Date: Mon, 25 Oct 1999 14:51:28 +0200 Subject: Research Positions Stiftung Caesar, Bonn GRADUATE POSITIONS AND POST-DOC The Modeling group of caesar is searching for candidates for a research project in industrial mathematics. The project is carried out in cooperation with industrial partners. Its subject is modeling, numerical simulation and optimal control of crystal growth processes. The models are nonlinear partial differential equations (heat transfer by conduction, convection and radiation). The position is limited to two years, a prolongation is planned. The ideal candidate has a master / Ph.D. in mathematics, physics, engineering, computer sciences or in a similar subject. He / She should be familiar with at least one of the subjects: scientific computing / mathematical modeling / partial differential equations / optimal control / crystal growth. Knowledge of the German language is not expected and only advantageous as far as everyday life is concerned. Salary is according to the German BAT IIa tariff. It depends on age and family status. Interested candidates should contact us as soon as possible and provide their CV, testimonies of their academic record (if possible in English or German translations) and a description of their scientific background and interests. One or two references of university teachers would be appreciated. Further questions? Please feel free to contact Axel Voigt, Stiftung caesar, Friedensplatz 16, 53111 Bonn, Germany, phone: +49(0)228-9656-236, e-mail: voigt@caesar.de. Please send your application to Ulrike Wermescher via e-mail: wermescher@caesar.de or to the address below. Stiftung caesar Center of Advanced European Studies and Research Postfach 7025 53070 Bonn, Germany Tel +49 (0)2 28 9656 - 122 Fax +49 (0)2 28 9656 - 111 http://www.caesar.de ------------------------------ From: Homer Walker Date: Mon, 25 Oct 1999 19:17:23 -0400 (EDT) Subject: Visiting Faculty Positions at Worcester Polytechnic Institute VISITING ASSISTANT PROFESSORSHIPS DEPARTMENT of MATHEMATICAL SCIENCES WORCESTER POLYTECHNIC INSTITUTE The WPI Mathematical Sciences Department invites applications for two visiting assistant professorships to begin in the fall of 2000. An earned Ph.D. or equivalent degree is required. Successful candidates must demonstrate strong research potential and evidence of quality teaching, and will be expected to contribute to the department's research activities and to its innovative, project-based educational programs. Preferred research interests are areas of applied and computational mathematics compatible with those represented in the department: partial differential equations with applications in fluid and continuum mechanics, composite materials, computational modeling and simulation, numerical analysis, optimization, control theory, applied probability, and discrete mathematics. Appointments will be made for two years, contingent on satisfactory teaching, with possible renewal for a third year at the discretion of WPI and the appointee. WPI's academic year is divided into four seven-week terms. The teaching load for these positions is five courses over the four terms, i.e., one course in each of three terms and two courses in the remaining term. WPI is a private and highly selective technological university with an enrollment of 2700 undergraduates and about 1000 full- and part-time graduate students. Worcester, New England's second largest city, offers ready access to the diverse cultural and recreational resources of the region together with opportunities for urban, suburban or rural lifestyles. The Mathematical Sciences Department has 24 full-time faculty and supports a PhD program and MS programs in applied mathematics and applied statistics, as well as a full undergraduate program. For additional information, see http://www.wpi.edu/+math. Qualified applicants should send a detailed curriculum vitae, a brief statement of their specific teaching and research objectives, and three letters of recommendation, at least one of which addresses teaching potential, to Visitor Search Committee, Mathematical Sciences Department, WPI, 100 Institute Road, Worcester, MA 01609-2280, USA. Applicants will be considered on a continuing basis beginning January 1, 2000 until the positions are filled. WPI offers a smoke-free environment. To enrich education through diversity, WPI is an affirmative action, equal opportunity employer. ------------------------------ From: Christine Cunningham Date: Mon, 25 Oct 1999 11:11:32 -0500 Subject: Research and Development Position at Wolfram Research Wolfram Research, makers of Mathematica, is seeking an outstanding candidate to add to its research and development team in the area of numerical computation. A successful applicant should have a Ph.D. in numerical analysis, applied mathematics, or a related discipline in which a significant component consists of practical implementation of mathematical algorithms. We are most interested in people who have a broad and general view of how their work fits into the overall framework of a technical computational system. Consequently we will consider applicants with expertise in a broad range of topics such as differential equations, linear algebra, optimization, root finding, and special function evaluation. Implementation experience in C/C++ and Mathematica skills would be a strong plus. Wolfram Reseach is located in Champaign, Illinois -- home of the University of Illinois. You can contact us: by filling out a web employment application at http://www.wolfram.com/company/opportunities/ (the best way) by sending email to resumes@wolfram.com by sending a fax to 217-398-0747 by sending regular mail to: Human Resources Department, Wolfram Research, 100 Trade Center Drive, Champaign, IL 61820-7237, USA ------------------------------ From: P. Wesseling Date: Tue, 26 Oct 1999 11:42:42 +0200 (METDST) Subject: Student Position at Delft University of Technology POSITION FOR PHD STUDENT Department of Applied Mathematical Analysis Faculty of Information Technology and Systems Delft University of Technology Applications are invited for a funded PhD studentship in the project "Unstructured staggered schemes for the Navier-Stokes equations". Further information may be found on the Internet at http://ta.twi.tudelft.nl/users/wesselin/project.html ------------------------------ From: Richard Braun Date: Tue, 26 Oct 1999 09:44:40 -0400 (EDT) Subject: Postdoctoral Positions at University of Delaware Postdoctoral Positions Department of Mathematical Sciences University of Delaware The Department of Mathematical Sciences at the University of Delaware has funding for two postdoctoral positions in scientific computing or computational and applied mathematics. These positions will be an important part of an active program which involves graduate students in industrial applied mathematics problems; the program is supported with an NSF Group Infrastructure Grant. Current projects involving industry include theory for electromagnetic scattering, micromagnetics, fluid mechanics, materials processing and free boundary problems. These positions will be part of a group of professors, graduate students and postdocs. The projects will involve working with both faculty and industrial scientists or engineers on research problems of mutual interest. The research part of position A will involve computation in fluid dynamics and/or materials science problems with free boundaries. The research for position B will involve scientific computation and/or modeling in fluid dynamics, electromagnetic scattering or computational finance. Both two-year positions have a salary of $42,500 per year with additional travel and expense money totaling $6,000; one course per semester of teaching will also be required. The duration of both positions is two years beginning in January 2000 or later. Applicants should have received the PhD before beginning at the University of Delaware, and the degree should be in the mathematical, computational or physical sciences. Please send a vita, research summary, a cover letter, and have letters of recommendation (including one addressing teaching) sent to: GIG Postdoctoral Positions Department of Mathematical Sciences University of Delaware Newark, DE 19716. Applications will be considered until the positions are filled. The University of Delaware is an equal opportunity employer. ------------------------------ From: Lyle Long Date: Tue, 26 Oct 1999 19:36:52 -0400 Subject: Faculty Positions at Penn State University Aerospace Engineering Penn State University Faculty Positions The Department of Aerospace Engineering invites applications from, and nominations of, highly-qualified individuals committed to teaching and research in all areas relevant to aerospace engineering. Rank, tenure status, and salary will be commensurate with experience and accomplishments. Candidates with inter-disciplinary interests who can work effectively as part of teams are encouraged to apply. Areas of particular relevance at this time include (but are not limited to): computational and/or experimental aerodynamics, composite structures, guidance and control, rotorcraft aerodynamics or rotorcraft flight dynamics, and propulsion. Potential candidates and nominators are encouraged to view our department website: http://www.psu.edu/dept/aerospace/ Applicants must have an earned doctorate in aerospace engineering or a related field, and at least one degree in aerospace engineering is desirable. Applications should include a cover letter specifying desired position, 2 copies of a resume, and a list of at least 3 references. Responses received at the address below before November 15, 1999 are assured full consideration, but the search will remain open until the positions are filled. Professor Cengiz Camci Chair, Faculty Search Committee Department of Aerospace Engineering 233A Hammond Building The Pennsylvania State University University Park, PA 16802 e-mail: c-camci@psu.edu ------------------------------ From: Esmond Ng Date: Wed, 27 Oct 1999 22:52:28 -0700 Subject: Postdoctoral Positions at Lawrence Berkeley National Laboratory The Scientific Computing Group at the Lawrence Berkeley National Laboratory has three immediate visiting postdoctoral openings in various computational science areas. Detailed descriptions of the openings can be found at the following URL's. 1) http://www.lbl.gov/CJO/NE11088.html Climate and earth sciences applications on massively parallel high performance computers. [An announcement of this opening appeared in NA Digest V.99, #41] 2) http://www.lbl.gov/CJO/NE11304.html Parallel algorithms for image analysis in single-particle reconstruction from electron micrographs. 3) http://www.lbl.gov/CJO/NE11316.html Large-scale electronic structure calculations and materials simulations. Applications/inquiries should be sent to employment@lbl.gov. The Lawrence Berkeley National Laboratory (LBNL) is a multidisciplinary DOE laboratory located on the hills of the campus of the University of California at Berkeley, and is an equal opportunity/affirmative action employer. ------------------------------ From: C. R. Traas Date: Fri, 29 Oct 1999 17:47:09 +0200 Subject: Postdoctoral Positions in The Netherlands PROJECT: WAVELETS AND THEIR APPLICATIONS This 4-year project, funded by the Dutch Science Foundation (NWO), consists of three research projects dealing with different aspects of wavelet research, and the establishment of a national seminar on wavelets, including an international visitor's programme. The projects are: (i) MORPHOLOGICAL WAVELETS WITH APPLICATIONS IN BINARY IMAGE PROCESSING (project leader: dr. H.J.A.M. Heijmans, Centre for Mathematics and Computer Science, Amsterdam). (ii) WAVELET-BASED SIGNAL DETECTION IN FUNCTIONAL NEUROIMAGING (project leader: dr. J.B.T.M. Roerdink, Institute for Mathematics and Computing Science, University of Groningen). (iii) WAVELET METHODS FOR NUMERICAL ANALYSIS (project leaders: prof. dr. C.R. Traas, University of Twente, and dr. H.G. ter Morsche, Technical University of Eindhoven). Below you find a more detailed description of projects (ii) and (iii), for which we have two open positions (one PhD, one postdoc). Applications should be addressed to the respective project leaders, as mentioned below under the different sub-projects. POST-DOC POSITION (30 MONTHS) AT THE UNIVERSITY OF TWENTE. TITLE: Wavelet Methods for Numerical Analysis SUMMARY: Wavelets and multiscale type methods are becoming increasingly important with respect to numerical simulation and scientific computing, in particular where large and complex problems have to be solved. Specifically in the following tasks a significant contribution of these methods is envisaged: - Preconditioning of large systems which may arise in the discretization of elliptic PDE's or integral equations. - Sparsening of dense matrices. - Adaptive approximation. The fundamental property of wavelets to be capable to zoom in onto local properties of a function, is a key to the expectations mentioned above. The research project concerns the investigation of the impact of wavelets onto the solution methodology in and around the Boundary Element Method, in particular the possibility of sparsening the systems' matrix. This impact is certainly dependent on the class of kernels considered. RESEARCH GROUP: The project will be carried out in the research group "Numerical Analysis" of the Mathematics Department of the University of Twente. The research interest of this group is in Splines and Wavelets and their applications in PDE's, integral equations and filtering. There will be close cooperation with the Numerical Analysis group at the university of Eindhoven, where related research is done within the same covering 4-year project. REQUIREMENTS: 1: PhD in Applied Mathematics 2: Affinity with wavelets and PDE's/Integral equations. HOW TO APPLY: Applications for the position, including a Curriculum Vitae (name, address, degree, date, etc.) and name and email address of two professional references, should be addressed (by surface mail) to Prof.dr.C.R.Traas University of Twente Faculty of Applied Mathematics P.O.Box 217 7500 AE Enschede The Netherlands Tel: +31 53 4893408 Email: traas@math.utwente.nl PhD POSITION (4 YRS) AT THE UNIVERSITY OF GRONINGEN Institute for Mathematics and Computing Science TITLE: Wavelet-Based Signal Detection in Functional Neuroimaging SUMMARY: Many techniques currently exist to produce images of the human brain, such as CT (Computerized Tomography), MRI (Magnetic Resonance Imaging) or PET (Positron Emission Tomography). These imaging techniques are not only useful to obtain images of brain structure, but also of brain function. The detection of significant changes in neurological activity is not an easy task, since in general these changes are small and distributed over the whole brain, although not in the same amount. Statistical analysis of image differences corresponding to different experimental conditions can be subdivided in two classes: techniques which first partition the brain into regions of interest, based upon anatomical structure, and techniques in which one creates images of a statistical parameter: Statistical Parametric Mapping, by applying statistical hypothesis testing to each element of the difference between the images with and without activation, based upon modelling the difference image as a realization of a Gaussian random field. The aim of the research is a study of wavelet decompositions of brain images to improve signal detection, and to establish a connection between the current detection methods in neuroimaging. This project is connected to GNIP: Groningen NeuroImaging Project, which involves many research groups from the Academic Hospital (AZG) and the local research school BCN (Behavioural, Cognitive and Neurosciences). RESEARCH GROUP: The project will be carried out in the research group `Scientific Computing and Imaging' of the Department. The research interests of the group are particularly concentrated in high performance computing for visual perception and neural-net modelling, morphological image processing, computerized tomography, scientific visualization and geometric algorithms. REQUIREMENTS: 1. MsC in Mathematics with strong affinity to Computer Science, or vice versa. 2. Experience in image processing and/or spatial statistics. 3. Demonstrably good computing skills. HOW TO APPLY: Applications for the position, including a Curriculum Vitae (name, address, degree, date, etc.) and name and email address of two professional references, should be addressed (by surface mail) to: Dr. Jos Roerdink University of Groningen Department of Mathematics and Computing Science P.O. Box 800 9700 AV Groningen The Netherlands Tel: +31-50-3633931 Email: roe@cs.rug.nl URL: http://www.cs.rug.nl/~roe ------------------------------ From: Vladik Kreinovich Date: Sun, 24 Oct 1999 11:11:30 -0600 (MDT) Subject: Contents, Reliable Computing Reliable Computing Volume 6, Issue 1, 2000 Special issue on Reliable Geometric Computations Guest editors: Helmut Ratschek, Jon G. Rokne Introduction to the Special Issue: What Can One Learn from Box-Plane Intersections? Helmut Ratschek, Jon G. Rokne 1-8 Robust and Efficient Ray Intersection of Implicit Surfaces Ole Caprani, Lars Hvidegaard, Mikkel Mortensen, Thomas Schneider 9-21 Correct Delaunay Triangulation in the Presence of Inexact Inputs and Arithmetic Jeffrey S. Ely, Anthony P. Leclerc 23-38 Exact Computation of Delaunay and Power Triangulations Marina Gavrilova, Helmut Ratschek, Jon G. Rokne 39-60 Removing Degeneracies by Perturbing the Problem or Perturbing the World Pierre Alliez, Olivier Devillers, Jack Snoeyink 61-79 Interval Constraint Plotting for Interactive Visual Exploration of Implicitly Defined Relations Timothy J. Hickey, Zhe Qiu, Maarten H. van Emden 81-92 Reminiscences "Back in the Good Old Days..." column edited by George F. Corliss Interval Integration L. B. Rall 93-94 ------------------------------ End of NA Digest ************************** -------