**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

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

=========================

* 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

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

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

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

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

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