From surfer.EPM.ORNL.GOV!nacomb Sat Aug 24 18:48:59 0400 1991 Received: by pyxis; Sat Aug 24 18:49 EDT 1991 To: pyxis!ehg Received: by inet.att.com; Sat Aug 24 18:49 EDT 1991 Received: by surfer.EPM.ORNL.GOV (5.61/1.34) id AA13728; Sat, 24 Aug 91 18:48:59 -0400 Date: Sat, 24 Aug 91 18:48:59 -0400 From: nacomb@surfer.EPM.ORNL.GOV (NA-NET) Message-Id: <9108242248.AA13728@surfer.EPM.ORNL.GOV> Subject: NA Digest, V. 91, # 34 Apparently-To: ehg@research.att.com NA Digest Saturday, August 24, 1991 Volume 91 : Issue 34 Today's Editor: Cleve Moler Today's Topics: Cubic & Quartic Equation Solvers GMRES Fortran Code UGLY Optimization Problems Wanted SIAM Conference in Minneapolis Does IEEE Arithmetic Stink? IEEE Arithmetic Stinks Less Than ... IEEE Arithmetic Japanese Receive US Researchers Postdoc Position at ORNL Workshop on Total Least Squares Pacific N.W. Numerical Analysis Seminar Netlib News: Big Files Submissions for NA Digest: Mail to na.digest@na-net.ornl.gov. Information about NA-NET: Mail to na.help@na-net.ornl.gov. ------------------------------------------------------- From: Herman J. Woltring Date: Mon, 19 Aug 91 07:59 MET Subject: Cubic & Quartic Equation Solvers Dear NA-NET readers, I should be grateful for FORTRAN code to solve (cubic and) quartic equations. It seems that the algorithm in section 3.8.2 in my edition of Abramovitz & Stegun is incorrect, while I am getting good results with the algorithm in section 5.5 of "Numerical Recipes" by Press et al. However, rounding errors in the quartic equation algorithm of section 3.8.3 in Abramovitz and Stegun make it difficult to take reliable branching decisions. Thanks in advance! Herman J. Woltring , Eindhoven, The Netherlands ------------------------------ From: John Richardson Date: 23 Aug 91 15:36:48 GMT Subject: GMRES Fortran Code Does anyone have, or know of an ftp site that has, f77 or other source code the implements the Generalized Minimum RESidual (any flavor) algorithm? Thanks, John Richardson Thinking Machines Corporation, Cambridge Mass., USA ------------------------------ From: Glen Clark <...!gatech!dscatl!opto!glen> Date: 23 Aug 91 13:29:00 GMT Subject: UGLY Optimization Problems Wanted Over the course of several years, we have written a suite of optimizers for constrained, non-linear problems. The original application was electromag- netics, but the core algorithms are not application- specific and we believe they may be useful for a broad spectrum of non-linear problems. Immunity to cheap, early gains is high and execution time compared to SA is very favorable. We'd like to find out just how good these algorithms are. Every mother thinks her child is beautiful, but there's nothing like a little bit of competition to give you a quick reality check. To that end, we're soliciting UGLY, non-linear, optimization problems (parametric, not combinatorial) in an effort to stump the system. If you have a particularly challenging optimization problem that you'd like to see humbled, we'd like to see if we can break our pick on it, at our expense. If interested, please send us a paragraph or two giving a general outline of the problem. Minimally, it should include subject area (aerodynamics, network loading, etc.) and a brief description of the particular application. Any information regarding the present state of the art in that application would be helpful, but is not essential. All replies will be acknowledged. C or FORTRAN problems are preferred, but interesting problems already coded in ada or pascal will also be considered. All exchanges will be held strictly confidential. Binding non-disclosure agreements available where appropriate. Glen Clark, P.E. gatech!dscatl!opto!glen Glen Clark & Associates Consulting Engineers Alpharetta, GA ------------------------------ From: SIAM Conferences Department Date: Tue, 20 Aug 91 11:57 EDT Subject: SIAM Conference in Minneapolis Dear Colleague: Just a friendly reminder.....if you have not yet registered for the conference on applied linear algebra, September 11-14, 1991, Minneapolis, Minnesota, please take a few minutes of your valuable time ....and register now -- before the deadline -- September 4. You can register by telephone -- 215-382-9800, by fax - - 215-386-7999, or by e-mail to: siamconfs@wharton.upenn.edu Thanks and see you in Minneapolis. SIAM Conferences ------------------------------ From: John Reid Date: Tue, 20 Aug 91 10:19:28 BST Subject: Does IEEE Arithmetic Stink? This is a response to Joe Grcar's article in NA Digest 91/33 (Aug 18). I think that he is attacking the wrong target. It is not IEEE arithmetic that stinks. It is the implementation of Fortran 77 that stinks. The Standard requires (page 15-8, lines 8-11 and page 15-10, lines 36-39) that the actual arguments in a procedure reference must agree in order, number, and type with the corresponding dummy arguments of the referenced procedure. Most implementations have no mechanism for checking this condition. Everyone makes silly mistakes from time to time and it is highly desirable that as many as possible are properly diagnosed, preferably before execution commences. As far as I can tell from Joe's description, his engineer's faulty program could have been diagnosed at link time. The situation will be better in Fortran 90. There are simple mechanisms for making the properties of the dummy arguments visible at compile time and I am expecting that libraries will make these available to their users by providing modules instead of procedures. An example is a module that contains nothing more than a single Fortran 77 procedure; the only change that a Fortran 77 programmer would need to make is to add a USE statement that names the module and thereby makes the interface visible to the compiler. John Reid, Atlas Centre, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX UK ------------------------------ From: John Nash Date: Mon, 19 Aug 91 11:13:49 EDT Subject: IEEE Arithmetic Stinks Less Than ... I trust that others who were involved in the IEEE development and approval process will respond to Joe Grcar's complaints at a technical level. The purpose of this note is to give the viewpoint of someone who -- though a minor participant in IEEE committees -- is mainly a user of their product in developing modest scientific computer programs. Grcar's points are taken as he presented them. (1) The standard makes simple things complicated. "In contrast, the SUN OS documentation for IEEE arithmetic is one hundred and sixty pages long." Surely this is a complaint about SUN documentation. The IEEE 754 standard is one of the shortest standards documents in the computer arena. Moreover, it DOES make things simple(r) for the user, because the properties of the arithmetic are reproducible. I recall Data General changing the radix from 2 to 16 between two releases of software! (2) The standard makes precision indefinite. Implementers (of compilers) should give the user a fairly sensible set of defaults e.g. underflow gracefully to zero, generate error exception on overflow, etc. Grcar's complaint here is one that such defaults are not provided. (3) The standard makes error analysis impossible. Someone else can field this one. (see (2) above). (4) The standard doesn't prevent failure, it only hides failure. The programmer is not absolved of the responsibility of checking the data against the real world. The IEEE arithmetic is a set of tools to keep the alligators down to waist level. (5) The standard makes debugging difficult. "The standard allows programs to run with garbage for data. These are the hardest programs to debug." If you (or the compiler writer) turn off the traps (see (2) above), like the operators at Chernobyl or Bhopal turned off the safety devices, you can expect to have accidents. Try driving along a mountain road without steering wheel or brakes. Grcar's example: This example is akin to a family disaster which occurred when the cook made zabaglione with salt instead of fine sugar. If you attach the wrong libraries to a linker, you will have trouble, but it is not the fault of the arithmetic. In this regard, I like programs which come with a modest test output one can try to reproduce before using the program seriously. In my experience on PCs, compilers have become a whole lot nicer to use since the writers adopted IEEE as an option. More recently it is often the default, and for those who don't have the 80x87 or a comparable co-processor, there are software emulations which are usually invoked automatically. I am tempted to infer that Joe Grcar has been the victim of an implementation which is user-UNFRIENDLY. A useful exercise, if one is worried about the arithmetic or its default settings, is to run PARANOIA (available on NETLIB courtesy of many workers, in particular Kahan and Karpinski). Before responding here, I tried recently acquired Microsoft Quick C (1 flaw, 1 defect reported), and Turbo C++ (gave compile errors, which I will have to look into). John Nash, Faculty of Administration, University of Ottawa ------------------------------ From: F. W. Olver Date: Thu, 22 Aug 91 16:24:57 EDT Subject: IEEE Arithmetic Joe Grcar's severe criticisms of IEEE arithmetic in his message of Aug.14 may well touch resonant chords in the computing community. We, too, would be very interested in hearing details about similar complaints. The problem lies not so much with the IEEE standard as with the floating- point system itself. This system was widely adopted in the 1950's when the problem of rescaling to keep within the representable ranges of the fixed-point system became irksome AND when suitable hardware was constructed by the engineers. Although the floating-point system has proved to be a vast improvement on the fixed-point system, nevertheless it did not solve the rescaling problem completely. All too frequently programmers and software designers encounter the phenomena of overflow and underflow--- the "betes noires of portability" as W.S. Brown once dubbed them. The situation can be even worse than Joe Grcar depicts. In a problem encountered this summer at NIST (formerly NBS) concerning turbulent combustion, IEEE arithmetic yielded not the recognizable, but useless, NaN's or infinities, but quite reasonable-looking---and seriously erroneous--- graphs without an error message or other warning. The cause had nothing to do with the standard graphics packages being used. It was eventually traced to floating-point underflow. Although IEEE arithmetic was used it would have occurred with any currently available floating-point hardware. Neither the touted IEEE gradual underflow nor the use of double precision made any difference. (And even when the erroneous nature of the output was recognised it was clear that no simple rescaling would remedy the situation.) In recent years a new form of computer arithmetic has been under development as an alternative to the floating-point system. The new system is called the symmetric level-index (sli) system, and it has many advantages. First, the sli system is closed (in a natural way, not with artificial machine symbols) under arithmetic operations in finite-precision arithmetic, other than division by zero, of course. This abolishes the problems of overflow and underflow completely. Next, because the representation is mathematically determined it is natural and its description is brief---no gigantic committee was needed to create a specification. Thirdly, there is a natural error measure that is uniform in nature for all numbers.This error measure reduces to absolute precision or relative precision in appropriate circumstances, and is therefore called generalised precision. In short, all five forms of woe listed in Joe Grcar's message would be taken care of satisfactorily in the sli system. Predictably (because so much is now at stake), the big guns of the defenders of floating-point and the IEEE standard have already been trained on the new system. The odd thing, however, is that the arguments they are using--- slowness of execution speed, loss of precision (in their own carefully defined sense), and lack of requisite error analysis---are exactly the same as those used forty years ago by fixed-point diehards in attacking the then proposed floating-point system. Several papers and articles have already been published on the sli system and its companion, the level-index (li) system. A brief introduction appeared in the April issue of the Notices of the American Mathematical Society. For an indepth account see pp.95-168 of Lecture Notes in Mathematics No.1397 "Numerical Analysis and Parallel Processing", edited by P.R.Turner, Springer-Verlag, 1989. Software implementations are also available. Daniel Lozier (lozier@cam.nist.gov), Frank Olver (olver@bessel.umd.edu), and Peter Turner(prt@usna.navy.mil) ------------------------------ From: David K. Kahaner Date: Mon, 19 Aug 91 15:44:44 EDT Subject: Japanese Receive US Researchers ABSTRACT. Summary of NSF "Directory of Japanese Company Laboratories Willing to Receive American Researchers". The National Science Foundation sponsors an active Japan program for US scientists. As part of that program they have prepared a directory of approximately 150 Japanese companies that have said they are willing to receive American researchers at their laboratories. The list was compiled by mailing to 553 companies with more than 30 researchers listed in the "All Japan Research Institutes Directory". Of these, 284 companies responded and 154 provided positive responses. NSF's Directory lists each company as well as specific information about their activities, personnel, facilities, and the type of research that they are interested in supporting. Names and addresses of contacts are also given for each. This Directory, as well as other information can be obtained from the following address, Japan Programs Division of International Programs National Science Foundation Washington DC 20550 or by fax at (202) 357-5839. ------------------------------ From: David Walker Date: Tue, 20 Aug 91 08:10:04 -0400 Subject: Postdoc Position at ORNL RESEARCH POSITION AVAILABLE AT OAK RIDGE NATIONAL LABORATORY IN PARALLEL ALGORITHMS FOR LINEAR ALGEBRA A postdoctoral research position is available at Oak Ridge National Laboratory in parallel algorithms for linear algebra. The research will focus initially on the development of a library of portable, efficient routines for performing dense linear algebra computations on MIMD distributed memory concurrent computers. A subsequent goal will be the development of software for sparse matrix computations on these types of computer. The practical use of the library software will be demonstrated by using it to build large-scale applications that are transparently portable between different concurrent computers. The research to be conducted is part of a program involving Jack Dongarra and David Walker of Oak Ridge National Laboratory, Jack Demmel of University of California at Berkeley, Michael Heath of University of Illinois, and Danny Sorensen of Rice University. The position requires an in-depth knowledge of linear algebra algorithms for scientific computation, and practical experience with MIMD distributed memory concurrent computers. The appointment will be for two years, preferably beginning October 1, 1991, or shortly thereafter. Benefits of the position include a competitive salary, travel opportunities, access to state-of-the-art computational facilities, and collaborative research opportunities in a very active research program. Inquiries should be directed to: David W. Walker Bldg. 6012 / MS-6367 P. O. Box 2008 Oak Ridge Nat ------------------------------ From: Frank Luk Date: Tue, 20 Aug 91 16:56:31 -0400 Subject: Workshop on Total Least Squares A Workshop on Total Least Squares was held on August 12-15 in Leuven, Belgium, on the campus of the Catholic University. The two major organizing figures were Sabine Van Huffel and Gene Golub. There were 60 participants from many countries, from as far away as China. My three hour layovers at the JFK and Syracuse airports became insignificant after I learned from the Romanian speaker about her 36 hour sit-up train ride each way. Two distinguishing features of this workshop were the hospitality of the locals (all visitors were picked up at the Brussels airport on arrival, and returned there on departure), and a mix of participants from wide ranging areas such as chemistry, geophysics, medical imaging, scientific computing, signal processing, and statistics. The list of participants was studded with stars. To NA-NETers, three familiar names among many would be Bjorck, Golub, and Stewart. Participants from other disciplines included leaders of similar lofty statures. This workshop has achieved its goal of promoting scientific exchanges. I, for one, was quite ignorant of the many important practical applications of total least squares. It was gratifying to observe how several speakers tried to make their talks comprehensible to all by using notations from another discipline. Laughter roared when one speaker described how confused he quickly became, when he tried to use unfamiliar notations to prepare his slides; he finally decided that it would be safer for him to confuse the audience instead. A nontypical presentation was made by Richard Roy, who heads a small company in California. He revealed that, unlike other participants, he was there to try to make money out of the ideas presented, and he referred to the $VD, whereupon Golub asked if he had used a spell checker. Good food was abundant: lunches in a student cafeteria, and dinners in a restaurant. The renowned Belgian beer was always a topic of discussion. Some were amazed that a 9% beer could be selected as a lunch beverage in the student cafeteria. Everyone appreciated the huge amount of work put in by Van Huffel. particularly since she was due to become a mother five days after the workshop. Nonetheless, she gave two excellent talks, and attended other presentations and all social activities. Lastly, I would express my envy of the achievements of Joos Vandewalle at the Catholic University: not only has he built up a strong research group of almost ten students in matrix computing, he has also created an atmosphere permeated with friendliness and collegiality. His work was leadership by example at its best: he was probably the busiest driver shuttling between Leuven and the Brussels airport on the arrival and departure dates. Epilogue: Sabine gave birth to a boy on August 19. ------------------------------ From: Mike Bieterman Date: Thu, 22 Aug 91 13:42:23 PDT Subject: Pacific N.W. Numerical Analysis Seminar This is to announce the fifth annual PACIFIC NORTHWEST NUMERICAL ANALYSIS SEMINAR BOEING COMPUTER SERVICES BELLEVUE, WASHINGTON SEPTEMBER 21, 1991 SCHEDULE COFFEE: 8:30 AM WELCOME: 9:00 AM FIRST TALK: 9:15 AM DINNER: 6:00 PM SPEAKERS Ian A. Cavers, University of British Columbia, - chosen as "best student abstract" - ``Complete Spectrum Determination for Symmetric Sparse Matrices" Adel Faridani, Oregon State University, ``Local Tomography" Tom Grandine, Boeing Computer Services, ``Some Numerical Computations Arising in CAD" Robert O'Malley, University of Washington, ``Asymptotic/Numerical Methods for Differential-Algebraic Equations" Brian Tomas, University of Washington \& Boeing Aerospace, ``An Introduction to Wavelets for Computation" Brian Wetton, University of British Columbia, ``Finite Difference Methods for Navier Stokes with Boundaries: Vorticity and Primitive Variable Methods" CONTRIBUTED POSTERS Cleve Ashcraft, Boeing Computer Services, ``On formulating general sparse and multifrontal as extremal members of one algorithm family". John T. Betts and Paul D. Frank, Boeing Computer Services, ``Sparse Nonlinear Programming and its Application to Trajectory Optimization". Forrester Johnson, Robin Melvin, Dave Young, Dave Foutch, John Bussoletti, and Mike Bieterman, The Boeing Company, ``Propulsion System Exhaust Simulation Using Full Potential and Euler Formulations". Ping Lin, University of British Columbia, ``Remarks on a Mildly Nonlinear Turning Point Problem". Dan Pierce and John G. Lewis, Boeing Computer Services, ``Sparse Rank Revealing QR Factorization". Andre Weideman, Oregon State University, ``Singualrities in an Integrable Semi-discretization of the Nonlinear Schrodinger Equation". Laurence B. Wigton, Boeing Commercial Airplane Group, ``High Quality Grid Generation Using Laplacian Sweeps". Dan Curtis and Elizabeth Kirby, Boeing Computer Services, ``Some Examples of Scientific Visualization at Boeing". Additional poster presentations are welcome. If you would like to contribute one, please contact the organizers to assure space. In addition to the talks and poster session, the day will include a catered dinner at Jim Phillips' home. The dinner will feature Northwest delicacies (poached salmon among others) and microbrewery beer. The cost of the dinner will be $15 for adults and $10 for children. Please indicate on your registration if you will be attending the dinner and make checks for the dinner payable to Roger Grimes. During the seminar, coffee, drinks and lunch will be provided by The Boeing Company. REGISTRATION Register by September 16. We need adequate time for Boeing security to issue visitor's passes. Please be aware that late registrations will cause us some inconvenience. You may register for the seminar by e-mail or or regular mail. Please, in your mail, indicate how many people will be attending the dinner. Make checks for the dinner payable to Roger Grimes. (You may pay either when you send in your registration or at the seminar.) If you do not plan to attend the dinner, there will be no fees. Note: Persons under eighteen will not be permitted to attend the seminar. LOCATION Boeing Computer Services 33-07 Building 2760 160th Avenue South East Bellevue, Washington A map will be sent by mail. If you receive this announcement via electronic mail and do not receive a copy (with included map) via regular mail within one week's time, you can request a regular mail copy by contacting one of the organizers. If you have any questions or concerns, please do not hesitate to contact a member of the organizing committee. They are: Mike Bieterman - (206) 865-6272 - mbb5289@espresso.boeing.com Dave Ferguson - (206) 865-3521 - drf@espresso.boeing.com Roger Grimes - (206) 865-3585 - rgrimes@espresso.boeing.com John Lewis - (206) 865-3510 - jglewis@espresso.boeing.com Their common mailing address is: Boeing Computer Services Attn: --------- MS 7L-21 P. O. Box 24346 Seattle, Washington 98124-0346 See you on September 21. ------------------------------ From: Eric Grosse Date: Sat, 24 Aug 91 11:42 EDT Subject: Netlib News: Big Files \documentstyle[twocolumn]{article} \title{Netlib news: big files} \author{Eric Grosse}{} \begin{document}\maketitle {\sloppy In the early days of netlib, most files were of modest size. A typical request, say for the ``real symmetric'' driver from eispack, produced a reply of 30 kilobytes or less. The occasional Fortran program of more than 100 kilobytes was split arbitrarily into pieces for mailing; these had to be glued back together by the recipient. Now the collection includes large differential equation and optimization codes, packages written in C where specific filenames matter, and large bibliographies. A variety of mail size limits are appearing in the network. The use of Unix ``shell archives'' for transferring collections of files has become widely understood and accepted. In light of all this, it is clearly time for netlib to adapt. This column announces three changes for dealing with the problem of big files: ftp, revised mail splitting, and user-specified mail limits. We allow ftp access to a copy of the netlib files. Ftp is a file transfer protocol widely available on machines connected to the Internet. Using whatever syntax is appropriate for your local system, connect to research.att.com (also called 192.20.255.2) and login using the name ``netlib''. You'll be asked for your email address, so that we can keep an accurate log of activity and send you bug fixes if, heavens forfend, serious problems should be uncovered. Set ``binary'' mode, if your version of ftp doesn't do that automatically. Then use the ``dir'', ``cd'', and ``get'' or ``mget'' commands to retrieve desired files. Many have a ``.Z'' suffix indicating that they need to be uncompressed after the transfer. If this all sounds too difficult or confusing, just stick to email. Netlib now uses a new mechanism for splitting up its reply into multiple mail messages. The messages you will now receive are a shell archives, scripts to be executed using the Unix ``sh'' command. (People on other operating systems will have to edit manually.) After executing each message, in arbitrary order, the netlib files will be recreated on your system with their original names. In the case of files too big to send in a single message, this is done by sending temporary partial files; each script checks to see if all the partial files have arrived and, if so, assembles them into the original big file. But you don't need to worry about that; it is all automatic. In some cases, an author's contribution to netlib is already in the form of a shell archive. So whether you get it by ftp or by executing mail messages, you still need to execute the file another time to do the final unpacking. Yes, recursion can be confusing. By default, netlib splits its reply into messages of at most 100 kilobytes. This satisfies most machines on the Internet. To change the limit to, say, 20 kilobytes, you can give netlib the command ``mailsize 20k''. Initially these changes are installed only at research.att.com, so that I can respond to suggestions for improvements. Assuming the new mail splitting meets with general approval, it will be installed on the other netlib nodes. As an alternative to ftp, Jack Dongarra will soon be releasing an X-windows interface, which will allow downloading files from netlib@ornl.gov. A final word regarding big files: if your mail connection to netlib still depends somewhere along the path on dialup links, be sure you don't abuse someone else's hospitality, lest your service be cut off. \section*{Recent additions} PCON61 (the latest version of Rheinboldt and Burkardt's well-known program for continuation) has been installed. ``Program options include the ability to search for solutions for which a given component has a specified value. Another option is a search for a limit or turning point with respect to a given component.'' In the {\bf opt} library, you will find Toint's {\bf ve08ad}, a subroutine which minimizes a partially separable objective function with optional bound constraints. Though the code is unchanged, the recent appearance of Total Least Squares in SIAM's Frontiers book series merits notice. For details, ``send index for {\bf vanhuffel}''. {\bf Confpack}, by Gutknecht and Hough, implements conformal mapping by numerical solution of Symm's integral equation. ``send index for conformal.'' Gerard Holzman's {\bf spin} package for protocol validation is out of the customary (scientific computing) scope of netlib but should interest people in distributed computing. The {\bf pvm} library has been installed. From the abstract: ``PVM stands for Parallel Virtual Machine. It is a software package that allows the utilization of a heterogeneous network of parallel and serial computers as a single computational resource. PVM consists of two parts: a daemon process that any user can install on a machine, and a user library that contains routines for initiating processes on other machines, for communicating between processes, and synchronizing processes.'' TOMS algorithms 685 (separable elliptic PDEs) and 686 (updating QR factorizations) arrived in February. F2c, cheney-kincaid, kincaid-cheney, dassl, gcv, a/loess, fn/alngam, fn/ci, misc/netlib, picl, pltmg, port/linpar, and numerous other files have been updated. In general, if you're wondering whether a file has been added in a particular directory or whether it has been modified recently, you can try a request like ``send directory from eispack''. That file is automatically recreated nightly, and hence tells the truth even when the netlib administrator is too busy to keep the ``index'' and ``changes'' files up to date. {\em If you're new to netlib, send e-mail containing the line ``help'' to one of the Internet addresses \begin{verbatim} netlib@research.att.com netlib@ornl.gov netlib@nac.no netlib@draci.cs.uow.edu.au \end{verbatim} or uucp address {\tt uunet!research!netlib}. A few minutes later, assuming you have speedy mail connections, you will receive information on how to use netlib and an overview of the many mathematical software libraries and databases in the collection.} {\em Eric Grosse can be reached at the Computing Science Research Center, AT\&T Bell Laboratories, Murray Hill NJ 07974, USA or by email at {\tt ehg@research.att.com}. Unix is a registered trademark of AT\&T Bell Laboratories. This column was written August 24, 1991.} }% end sloppy \end{document} ------------------------------ End of NA Digest ************************** -------