krj@csri.toronto.edu (Ken Jackson) (05/09/88)
NA Digest Sunday, May 8, 1988 Volume 88 : Issue 19 Today's Editor: Cleve Moler Today's Topics: Re: Fast Floating Point Software for Microprocessors IMACS World Congress Signal Processing Software Special Issue on Parallel Optimization Index Issue of Linear Algebra and its Applications Graduate Assistantships at Utah State ------------------------------------------------------- From: David Hough <dgh@Sun.COM> Date: Sun, 1 May 88 13:05:29 PDT Subject: Re: Fast Floating Point Software for Microprocessors Summary of original posting: Brad Templeton is trying to implement the fastest possible software floating point for the 8086. He doesn't care about getting the rounding correct. Summary of my response: Don't waste your time. The summary reflects my own experience in improving the software floating point implementation on the Sun-2 and Sun-3. [Sun experts know it as -fsoft]. There is almost no perceived value in either a fast correct implementation or a faster incorrect implementation of floating-point arithmetic in software for processors for which good hardware floating point is readily available. As far as I know all IBM-PC's and their clones have provision for 8087's, which can be obtained around here for < $100 in retail quantity 1. While the 8087 is not free from fault it is faster than any software implementation and of higher quality than most. By mistake I decided to have -fsoft be the default code generation option on the Sun-3, because the emulator software available from Motorola was extremely slow and the 68881 hardware initially available had some bugs. So I devoted some effort to improving the software floating point, within the constraint of correct IEEE rounding. However everybody to whom either speed or full IEEE correctness was important eventually bought the 68881 (which was and is only optional on the cheapest Sun-3 anyway) and I would have to say that the only thing people noticed about the software floating point was that it didn't support IEEE modes or exception handling and it didn't produce the same answers as -f68881. In retrospect what I should have done was to have -f68881 code generation (fastest possible assuming 68881 hardware present) be the default, and have the kernel emulate the hardware if it was missing. This is the approach taken in the Sun-4, for instance. Anybody who cares about floating-point performance will get the hardware sooner or later anyway. As for what's to be done on IBM PC's, I'd suggest coding that assumes the 8087 is present and exploits it optimally, with the emulator invoked automatically if the hardware is missing. As for what happens when you tolerate sloppy rounding to make it "faster", simply recall what happened to someone else who tried this, as relayed to me through an intermediary: The program that did this was Spice. I had a bug in my sqrt that resulted in noise in the LSB of the dbl prec result. Rounding then occurred (correctly), but it was too late for the lsb. Something about the convergence criteria of the Spice model made it run about three times longer due to the non-monotonic behavior. (I'll try to find our local Spice expert for more details on that.) This caused our benchmarking people to agonize for several days on why we were so much slower than expected, until I tried Kahan's Paranoia program, which quickly complained about the non-monotonicity. Fixed the bug, and Spice sped up by a factor of 3 or so. Kahan thinks that monotonicity is extremely important for intrinsics, and after that I agreed with him. As mentioned previously, Kahan's lecture series is starting this week. Anybody interested in subscribing as an absentee participant should send me e-mail for the details - in return you get the privilege of helping to defray the fixed costs of the course. -- David Hough Sun Microsystems ------------------------------ From: Robert Vichnevetsky <vichneve@aramis.rutgers.edu> Date: Mon, 2 May 88 13:57:30 EDT Subject: IMACS World Congress ========================= * 12th IMACS WORLD CONGRESS * * ON SCIENTIFIC COMPUTATION * ========================= July 18-22, 1988 - Paris, France ================================ The 12th. IMACS World Congress will take place at the historic site of the Sorbonne/Lycee Louis le Grand in the Quartier Latin, a central area of Paris known since the Middle Ages for its prestigious Schools and its University. The program of the Congress features some 900 papers, to be presented by authors from almost every country in the world. The topics cover a wide range of interests, including Computational Mathematics, Numerical Analysis, Modelling of Systems, Computational Physics, Computational Acoustics, Applications in Science and Engineering, and Hardware and Software for Scientific Computation. Registration forms, and the preliminary program, which contains a listing of all papers and social events, may be obtained by writing to: IMACS Secretariat Attn: K. Hahn Rutgers University Dept. of Computer Science New Brunswick, NJ 08903 USA Tel: 201-932-3998 ARPANET: khahn@aramis.rutgers.edu ------------------------------ From: Jeff Dunn <dunn%nrl.decnet@nrl.arpa> Date: 3 May 88 06:57:00 EDT Subject: Signal Processing Software One of the workers here has need of a signal processing code which will run on an IBM PC, that is, has easily adjustable array sizes and is standard FORTRAN. He wants a package which will calculate spectra and cross spectral density matrices for 2 dimensional data. He also wants to be able to do filtering easily, ie. he wants filters to be part of the code. If anyone has such a code and is willing to share it with us, we would be most appreciative. Thanks, Jeff Dunn <dunn@nrl.arpa> ------------------------------ From: Stavros Zenios <ZENIOS@wharton.upenn.edu> Date: Tue, 3 May 88 13:08 EST Subject: Special Issue on Parallel Optimization PARALLEL OPTIMIZATION ON NOVEL COMPUTER ARCHITECTURES Editors: Robert R. Meyer, University of Wisconsin Stavros A. Zenios, University of Pennsylvania Special volume of the "Annals of Operations Research". Vol. 14, 1988, approx. 400 pages This volume presents a collection of papers that describe the state-of-the-art in the rapidly evolving area of parallel optimization on novel computer architectures. They represent both theoretical contributions describing new ways of decomposing large-scale problems, and succesfull parallel implementations of existing and new optimization algorithms. Computational studies are reported on a wide range of parallel systems like the Alliant FX/8, Sequent Balance 21000, IBM 3090-600, CRAY X-MP, FPS T-20, the Connection Machine CM-1 and others. We also see here the use of parallel and vector supercomputers for analyzing large scale applications of optimization. Contents: Preface, by R.R. Meyer and S.A. Zenios G.B. Dantzig Planning Under Uncertainty Using Parallel Computing R.V. Helgason, J.L. Kennington and H.A. Zaki Parallelization of the Simplex Method O.L. Mangasarian and R. De Leone Parallel Gradient Projection Successive Overrelaxation for Symmetric Linear Complementarity Problems and Linear Programs J.-S. Pang and J.-M. Yang Two-stage Parallel Iterative methods for the Symmetric Linear Complementarity Problem A.T. Phillips and J.B. Rosen A Parallel Algorithm for Solving the Linear Complementarity Problem D.P. Bertsekas The Auction Algorithm: A Distributed Relaxation Method for the Assignment Problem M.D. Chang, M. Engquist, R. Finkel and R.R. Meyer A Parallel Algorithm for Generalized Networks S.A. Zenios and R. Lasken Nonlinear Network Optimization on a Massively Parallel Connection Machine R.H. Byrd, R.B. Schnabel and G.A. Shultz Using Parallel Function Evaluations to Improve Hessian Approximations for Unconstrained Optimization M.-Q. Chen and S.-P. Han A Parallel Quasin-Newton Method for Partially Separable Large Scale Minimization M. Lescrenier Partially Separable Optimization and Parallel Computing S. Wright A Fast Algorithm for Equality-Constrained Quadratic Programming on the Alliant FX/8 G.A.P. Kindervater and J.K. Lenstra Parallel Computing in Combinatorial Optimization J. Plummer, L.S. Lasdon and M. Ahmed Solving a Large Nonlinear Programming Problem on a Vector Processing Computer R.E. Haymond, J.T. Thornton and D.D. Warner A Shortest Path Algorithm in Robotics and its Implementation on the FPS T-20 Hypercube TO ORDER: (U.S.) J.C. Baltzer AG, Scientific Publishing Co., P.O. Box 8577, Red Bank, NJ 07701-8577 (International) J.C. Baltzer AG, Scientific Publishing Co., Wettsteinplatz 10, CH-4058 Basel, Switzerland ------------------------------ From: Hans Schneider <hs@vanvleck.math.wisc.edu> Date: Tue, 3 May 88 21:18:23 cdt Subject: Index Issue of Linear Algebra and its Applications LAA NEWS BULLETIN 100 volume index of LINEAR ALGEBRA AND ITS APPLICATIONS Volume 100 of LAA will be published during May. It contains the author index for papers published in the first 100 volumes of the journal. It also contains a list of all members of the editorial board since the inception of the journal and, to the extent possible, a list of all referees. A complete listing of special issues with their special editors and of conference reports, profiles (biographical articles), book reviews, and obituaries will also be included. Volume 100 may be purchased at a price of $40 from the publisher at the address below: Elsevier Science Publishing Co 52 Vanderbilt Ave New York NY 10017 Volumes 101, 102, 103, 104 and 105 will be published in rapid sequence and are expected to appear during May and June. ------------------------------ From: Homer Walker <UF7099%USU.BITNET@forsythe.stanford.edu> Date: Thu, 5 May 88 14:49 MDT Subject: Graduate Assistantships at Utah State Dear colleagues: The Mathematics and Statistics Department at Utah State University has several graduate assistantships still open for next fall. More information on these assistantships and how to apply for them is given in the flyer below. We would appreciate your bringing this to the attention of any prospective graduate students. Anyone wishing to communicate informally with me about this is welcome to do so. Homer Walker uf7099@usu.bitnet or na.walker@na-net.stanford.edu RESEARCH AND TEACHING ASSISTANTSHIPS Mathematics and Statistics Department Utah State University The Mathematics and Statistics Deparment at Utah State University has several research and teaching assistantships available for the 1988-89 academic year. The areas of interest for the research assistantships include numerical opti- mization, statistical computing, numerical solution of partial differential equations, and computational fluid dynamics. Qualified students can expect a stipend of at least $8000 for the year and out-of-state tuition waivers. Inquiries should be made immediately and directed to Graduate Chairman Mathematics and Statistics Department Utah State University Logan, UT 84322-3900 Phone: (801) 750-2809 ------------------------------ End of NA Digest ************************** ------- Reposted by -- Kenneth R. Jackson, krj@csri.toronto.edu (csnet) Department of Computer Science, uunet!csri.toronto.edu!krj (uucp) University of Toronto, krj@csri.toronto.cdn (ean x.400) Toronto, Canada M5S 1A4 krj%csri.toronto.edu@relay.cs.net (arpa) (416) 978-7075 krj@csri.utoronto (bitnet)