**Today's Topics:**

- Cellular Automata,PDEs,Boundary Conditions
- Franke Joins ONR, London
- FFT for IBM PC Wanted
- Perturbation of singular vectors
- GAMM Conference on CFD
- ANSI C - Third Public Review
- NATO Advanced Study Institute in Leuven
- Program Director Needed at NSF
- Congratulations Joe Keller
- Differentiation Arithmetic: Examples & applications

From: Bracy Elton <lll-crg.llnl.gov!elton@lll-winken.llnl.gov>

Date: 18 Aug 88 00:51:49 GMT

Hi, I'm wondering whether anyone is doing or knows of any work in using

cellular automata for modeling fluid flow problems. I'm particularly

interested in any analysis into the realization of Dirichlet and Neumann

boundary conditions in cellular automata for fluid flow problems.

Please respond via e-mail.

Bracy Elton

Lawrence Livermore National Laboratory

elton@crg.llnl.gov or

elton@llnl-crg.llnl.gov

------------------------------

From: Richard Franke <onr@ess.cs.ucl.ac.uk>

Date: Thu, 18 Aug 88 8:42:06 BST

I am now at the Office of Naval Research in London, where my mailing address

is:

Office of Naval Rsearch OR Office of Naval Research

Branch Office London, Box 39 223 Old Marylebone Road

FPO New York 09510-0700 London NW1 5TH, England

(telephone: 01-409-4471)

Regards,

Richard Franke

------------------------------

From: Walter Gander <gander%ifi.ethz.ch@relay.cs.net>

Date: 18 Aug 88 10:47 +0100

A friend of mine (Luciano Molinari) is looking for a fast FFT programm

for the IBM PC. Preferably written in C or Microsoft Assembler.

Please let us know where we could get such a software. Many thanks.

- Walter Gander

(na.gander@na-net.stanford.edu)

postal address: ETH Zuerich, Inst. f. Informatik, CH-8092 Zuerich,

Switzerland

------------------------------

From: Per Christian Hansen <mcvax!cuobs!pch@uunet.UU.NET>

Date: Wed, 17 Aug 88 18:13:03 +0200

I am interested in the following problem:

Let R be an upper triangular matrix with 1's on the diagonal and

elements R(i,j) that decrease in magnitude with the 'distance' from

the diagonal. Example: R may be the inverse of the Cholesky factor

of the matrix

| 1 .25 |

|.25 1 .25 |

| .25 1 .25 |

| . . . |

| . . |

which occurs in connection with spline approximations.

Let A = U*Sigma*V' be an ill-conditioned matrix with ill-determined

numerical rank derived from an ill-posed problem. Its singular values

decay gradually towards zero, and the number of oscillations in the

singular vectors U(:,i) and V(:,i) increase with i .

Finally, let A~ = A*R = (U~)*(Sigma~)*(V~)' .

What can then be said about the relations between the singular vectors

or singular subspaces of A and A~ ?

Experiments with MATLAB suggests that both U'*(U~) and V'*(V~) are

close to identity matrices.

Per Christian Hansen

Copenhagen University Observatory, Denmark

email to na.hansen@score.stanford.edu

------------------------------

From: Piet Wesseling <mcvax!dutinfh!piet@uunet.UU.NET>

Date: 18 Aug 88 14:33:54 EST (Thu)

First announcement and call for papers

The GAMM Committee for Numerical Methods in Fluid Mechanics organizes the

EIGHTH GAMM CONFERENCE ON NUMERICAL METHODS IN FLUID MECHANICS

September 27-29, 1989

University of Technology, Delft, The Netherlands

The subjects of the conference are:

1. Theory of numerical methods in fluid mechanics: finite difference methods,

finite element methods, spectral methods, etc. The emphasis will be on

innovations in methods.

2. Application of numerical methods to fluid mechanical problems in

aerodynamics,hydrodynamics, propulsion, fluid machinery, nuclear reactor

technology, meteorology, biomechanics, etc.

The duration of each presentation will be 20 minutes plus discussion. Talks

on work in progress are welcome. Prospective contributors are invited to

submit sufficiently detailed abstracts of 1 to 2 pages of text plus figures

and tables by MARCH 7, 1989. The abstracts should include: field of study,

definition of problem, approach, results and conclusions. The abstracts should

concern unpublished work.

A selection of papers will be made on the basis of these abstracts. Authors

will be notified of acceptance by May 20, 1989. The proceedings will be

published by Vieweg in the series Notes on Numerical Fluid Mechanics. A book

of abstracts will be available at the time of the meeting.

The conference language is English.

Please write to the correspondence address below if you want to be put on the

mailing list of the organizing committee.

Conference chairman: P.Wesseling, Dept. of Technical Mathematics and

Informatics

Conference secretary: W.J.Bannink, Dept. of Aerospace Engineering

Address all correspondence to: Mrs.R.Komen-Zimmerman

Congresbureau TU Delft

Stevinweg 1, 2628 DELFT, THE NETHERLANDS

Telephone (015)781340 Telex 38151 butud nl

Telefax (015)781855

CONFERENCE SPONSORS: Royal Netherlands Academy of Sciences

Shell International Petroleum Company Ltd.

N.V. Nederlandse Gasunie

Philips Research Laboratories

Gesellschaft fuer Angewandte Mathematik und Mechanik

IBM Nederland N.V.

AKZO

Delft University of Technology

Please post

------------------------------

From: David Hough <dgh@Sun.COM>

Date: Thu, 18 Aug 88 20:34:48 PDT

The third public review of X3J11's Draft ANSI Standard C

is nearing its close on 1 September 1988. This third review

is based upon a draft dated 13 May 1988 which is little

changed from earlier drafts except that the controversial

"noalias" keyword was removed.

Consequently the Draft still leaves a good deal to be

desired from the numerical point of view.

I have two documents available for electronic distribution.

I will be glad to send you tbl/troff -ms source for these;

please specify which if you only want the second one described below.

Unfortunately the Draft ANSI Standard itself is not publicly

available in electronic form.

The first available document is my 29 March 1988 commentary prepared

for the second public review period (30 pages), with X3J11's

formal responses of 22 April interspersed. The following were

co-conspirators:

Greg Astfalk Larry Breed D. Burton

W. J. Cody Iain Johnstone W. Kahan

Zhishun Alex Liu David Mendel Jim Meyering

K-C Ng Gene Spafford Philippe Toint

Stein Wallace

The second available document is a draft, subject to revision

until about 25 August, of my commentary for the third public

review. It's only about 10 pages since I generally avoided

directly repeating what was in the earlier document.

I'm looking for additional reviewers and conspirators

on this one. The abstract follows:

The proposed C standard suffers numerical

shortcomings - many inherited from its precursors

- in areas of interest to providers of portable

mathematical software. I comment in detail upon

the following aspects of the proposed standard:

Comment #1, Section 3.9: encourage sound practices

Comment #2, Section 3.9: disparage hazardous practices

Comment #3, Section 1.1: emphasize surprises in rationale

Comment #4, Section 1.1: anticipate supplemental standards

Comment #5, Section 2.2.4.2: use "significand"

Comment #6, Section 2.2.4.2: <float.h> has too many names, not enough information

Comment #7, Section 3.2.1.4: round conversions between floating types

Comment #8, Section 3.5.4.2: fix arrays

Comment #9, Section 4.5: exceptions in mathematical functions

Comment #10, Section 4.5: tell more in the rationale

Comment #11, Section 4.5: standardize hypot

Comment #12, Section 4.5.4.6: delete modf

Comment #13, Section 4.7: specify which signals can arise

------------------------------

From: Gene Golub <golub%kulesat.uucp%blekul60.bitnet@Forsythe.Stanford.EDU>

(Gene Golub in Leuven)

Date: Fri, 19 Aug 88 10:43:36 GMT

REPORT of the NATO Advanced Study Institute

The NATO Advanced Study Institute on "Linear Algebra, Digital

Signal Processing and Parallel Algorithms" took place in Leuven

from August 1 through August 12. There were over 90 participants

(including the 15 invited speakers) from 16 countries and there

was a significant industrial participation.

The invited speakers included : M. Bellanger (TRT, France), B.

Bitmead (ANU, Australia), A. Bjorck (Linkoping, Sweden), R. Brent

(ANU, Australia), Y. Genin (PRLB, Belgium), S. Hammarling (NAG,

England), I. Ipsen (Yale, USA), T. Kailath (Stanford, USA), F. Luk

(Cornell, USA), J. McWhirter (RSRE, England), G. Meurant (CEL,

France), D. Sorensen (Argonne, USA), J. Vandewalle (KUL, Belgium),

and the codirectors G. Golub (Stanford, USA) and P. Van Dooren

(PRLB, Belgium).

The goal of this meeting was to synthesize the three topics

mentioned in the title as there is currently a great deal of

activity in each one of these areas. It was felt that there were

many interactions at the meeting, not only between participants

that were familiar with each one of these areas but also

between people working in different areas of interest.

The Proceedings will include the invited presentations, some

of the contributed talks and all the abstracts. They will be

published by Springer-Verlag in the NATO ASI Series and should

appear early next year.

The following areas emerged as major themes at the meeting :

1) Singular value and eigenvalue decompositions, including

applications

The current techniques used for the computation of the singular

values and eigenvalues of matrices were addressed by several

speakers. Modified singular value and eigenvalue problems were

also discussed, especially in view of their application in various

signal processing problems (e.g. total least squares, generalized

SVD, time varying eigenvalue problems etc.)

2) Toeplitz matrices, including special algorithms and

architectures

Several speakers focussed on so-called fast or O(n**2) algorithms

for computing L.L' and Q.R decompositions of a Toeplitz matrix.

Special attention was given here to Levinson and Schur type

algorithms as well as to their split version. The fast algorithms

based on displacement ranks and on updating and downdating were

also addressed.

3) Recursive least squares in linear algebra, digital signal

processing and control

The recursive least squares algorithms occurring in signal

processing and control often have a specific structure, hence

allowing for fast solutions. Various of these fast algorithms were

explained and their potential numerical deficiencies were pointed

out. Issues as error build-up, error feedback, exponential

windowing, sliding windowing and so on, were addressed.

4) Updating and downdating techniques in linear algebra and

signal processing

The two main techniques of updating and downdating are low rank

corrections and low norm corrections. Low rank corrections are

used in divide and conquer methods for eigenvalue and singular

value computations and were shown to yield powerful parallel

computational methods. They can also efficiently be used for

computing new least squares solutions for modified data fitting

problems using the theory of orthogonal polynomials and modified

moments. Low norm corrections are used in slowly time varying

problems as encountered in various signal processing problems.

5) Error analysis and stability of algorithms and sensitivity

analysis of special recursive least squares problems

Error propagation in linear algebra is a well established

discipline but insufficiently known to the signal processing

community. Their basic principles were explained and their

application to specific problems in signal processing were

addressed (fast recursive least squares, Toeplitz solvers, Kalman

filtering, and so on). The relevance of special forms of stability

(weak, strong, mixed stability) was also emphasized in problems of

signal processing and linear algebra with special structure.

6) Special architectures (including supercomputers and distributed

processor arrays) for linear algebra and signal processing

Exploiting the parallelism of present (and future) computer

architectures is an area of significant interest the last few years.

The state of the art in computational algorithms for supercomputers

and distributed arrays of processors (such as systolic arrays) were

widely covered. Also special problems in linear algebra and signal

processing were given full attention.

Although most of the presentations can easily be classified in one

of the above "themes", it became apparent during the meeting that

there was a strong interconnection between several of the themes.

This lead to lively discussions both during lectures and breaks.

Several of the contributed talks focussed on specific applications

of these topics. In particular we mention here radar technology,

medical applications and robotics.

For the organizing committee,

Gene Golub Paul Van Dooren

------------------------------

From: Melvyn Ciment <mciment@note.nsf.gov>

Date: Fri, 19 Aug 88 17:44:53 -0400

The DIVISION OF ADVANCED SCIENTIFIC COMPUTING, NATIONAL SCIENCE

FOUNDATION, invites applications for the position of Program

Director, Centers. This program is responsible for the management

and development of the five NSF National Supercomputer Centers.

The current Program Director, Paul Rotar, will be returning to NCAR

as of December 1, 1988.

Interested persons should contact;

Dr. Melvyn Ciment,

Acting Director

DASC, NSF,

1800 G Street, N. W.

Washington D.C. 20550

Phone 202-357-7558.

E-mail; mciment@note.nsf.gov

------------------------------

From: Gene Golub <prlb2!kulcs!kulesat!golub@uunet.UU.NET>

(Gene Golub in Leuven)

Date: Thu, 11 Aug 88 14:31:42 GMT

Joe Keller, Professor at Stanford and a former VP of SIAM, was awarded the

National Medal of Science on July 15. Keller was cited for "his outstanding

contribution to the geometrical theory of diffraction....."

Congratulations, Joe, for this award; it's further recognition of your

great contributions.

Gene Golub

------------------------------

From: George Corliss <georgec@marque.mu.edu>

Date: Fri, 19 Aug 88 10:59:43 CDT

We are currently compiling a bibliography on automatic differentiation

(differentiation arithmetic) and its applications. If you know of

1. work on computing numerical values of derivatives or partial derivatives

from recurrence relations, or

2. applications which would benefit from the ability to compute derivatives

accurately and efficiently,

please e-mail or surface mail citations to either of us.

For those people who are unfamiliar with differentiation arithmetic, it

is the calculation of the VALUES of derivatives of a function using

recurrence relations derived from the rules of calculus. It is neither

symbolic (no formula for derivatives is formed) nor numeric (no finite

differences are computed). An N-term Taylor series can be computed accurately

in O(N^2) time. Two basic references are: Rall, "Automatic Differentiation:

Techniques and Applications", and Kagiwada, et al., "Numerical Derivatives

and Nonlinear Analysis".

Applications include optimization, solving nonlinear systems, Taylor series

solutions of ordinary differential equations, and interval techniques for

bounding remainder terms.

Thank you in advance.

George Corliss

Department of Mathematics, Statistics and Computer Science

Marquette University

Milwaukee, WI 53233 USA

UUCP: ...!uwvax!marque!georgec

INTERNET: georgec@marque.mu.edu

BITNET: 6591CORL@mucsd

NANET: na.corliss

phone: (414) 224-6599

Paul Davis

School of Mathematics

University of Bristol

University Walk, Bristol

BS8 1TW, England

JANET: msa.bristol.ac.uk!DavisPH

BITNET: ukacrl!msa.bristol.ac.uk!DavisPH

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End of NA Digest

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