Subject: NA Digest, V. 91, # 20

From: [email-masked] (NA-NET)
Date: Sun, 19 May 91 17:48:54 -0400

NA Digest   Sunday, May 19, 1991   Volume 91 : Issue 20

Today's Editor: Cleve Moler

Today's Topics:

     Preregistration Deadline for ICIAM 91
     Alexandre Chorin Elected to NAS
     Prof. Dr. Hansjoerg Wacker
     Advice on Scientific Workstations Sought
     Non-separable Elliptic PDE Solver
     Very Fast Poisson Solvers
     Vectorized Spherical Harmonics Routine
     Iterative Method for Sparse Least Squares Problems
     Computational Experiments for Numerical Analysis Instruction
     Fox Prize, 1991
     Parallel Numerical Analysis Workshop

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

From: SIAM Publications Department <[email-masked]>
Date: Fri, 17 May 91 14:31 EDT
Subject: Preregistration Deadline for ICIAM 91

ATTENTION ICIAM 91 SPEAKERS AND PARTICIPANTS

You can still save $50 on the conference registration fee if your
payment is received on or before June 14, 1991.  If you've misplaced
your preliminary program, please contact SIAM.  The conference and
hotel registration forms will be sent immediately upon your request.

Contact:  [email-masked]
or phone:  215-382-9800
   fax:    215-386-7999

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

From: Paul Concus <[email-masked]>
Date: Fri, 17 May 91 11:39:56 PDT
Subject: Alexandre Chorin Elected to NAS

Alexandre Chorin has been elected to the U. S. National Academy of Sciences.
This honor is in recognition of his work in numerical methods, computational
fluid mechanics, and turbulence theory.  Congratulations, Alexandre!

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

From: Heinz W. Engl <[email-masked]>
Date: Tue, 14 May 91 15:25:02 SDT
Subject: Prof. Dr. Hansjoerg Wacker

On May 14, 1991, Prof. Dr. Hansjoerg  Wacker of the Johannes-Kepler-
Universitaet Linz (Austria) has died.
Prof. Wacker got his PhD from the Technical University of Munich.
He held the Chair for Numerical Analysis here since 1974 and worked
mainly on Continuation Methods and Nonlinear Optimization.
In recent years, his main effort was to cooperate with industry on
various research projects, thus contributing a lot to the building up
of Industrial Mathematics in Austria.
Prof. Wacker has written several books and about 80 scientific papers.
He was on the Editorial Boards of Zeitschrift fuer Operations Research,
Computing, Mathematical Engineering in Industry, and Surveys on Mathematics
for Industry.

His death is a great loss for mathematics in Austria and for Industrial and
Applied Mathematics in general.

Heinz W. Engl, Linz

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

From: Fred Hickernell <[email-masked]>
Date: Wed, 15 May 91 17:15 +08:00
Subject: Advice on Scientific Workstations Sought

My institution is considering purchasing some workstations but have not yet
decided on the which brand (Sun, HP, IBM, DEC, etc.) or configuration.
Although we are well-endowed with microcomputers and have some old VAXes,
we do not yet have any workstations.  Thus, I would be interested in
receiving any advice you might have.

We intend to use the workstations to support faculty and graduate student
research as well as upper level undergraduate teaching and project work.
The work we are doing (or want to do) includes numerical PDEs, numerical
linear algebra, scientific visualization, image processing and
computational statistics.  We will use packages (e.g. MATLAB, SAS, NAG,
IMSL) as well as languages (e.g. FORTRAN, C).  Virtually all computers on
campus are networked through ethernet.  Our budget is modest, but we should
be able to buy something an order of magnitude better than a high-end
microcomputer (i486, Mac IIfx).

What is your idea of a starter system that could grow as budget allows?

Thanks,

Fred J. Hickernell                           [email-masked]  (internet)
Department of Mathematics                    [email-masked]     (bitnet)
Hong Kong Baptist College                    (852) 339-7015  (office phone)
224 Waterloo Road                            (852) 338-8014           (fax)
Kowloon, HONG KONG                           (852) 698-6744    (home phone)

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

From: Michael Page <[email-masked]>
Date: Thu, 16 May 91 11:32:06 +1000
Subject: Non-separable Elliptic PDE Solver

Before I reinvent the wheel, I am seeking a public-domain subroutine which
solves a non-separable two-dimensional elliptic p.d.e. on a non-uniform grid 
in a rectangular domain with Dirichlet boundary conditions.  My current
application has no cross-derivative terms but this is not crucial.  I would
prefer a Fortran routine but (beggers can't be choosers) either C or Pascal
would be fine.

Previously I have used the BLKTRI routine (from FISHPACK), but now I need
a routine for a non-separable equation.

Judging from what I have heard, a multigrid method seems to be the most
efficient way to do this (but I am open to other suggestions).  For example,
an article in the proceedings of the `Multigrid Methods' conference in 1981
(Lect Notes in Math, 960) mentions the release of a suitable code called
MGOO by Foerster and Witsch.  If this code is freely distributable I wondered
if someone could either send me a copy or direct me towards an anonymous FTP
site.  (I have looked in our local shadow of netlib.)  Recommendations
(and locations) of other suitable codes would also be appreciated.

Thanks in advance,

Michael Page                         (na.page or [email-masked])
Mathematics Department
Monash University
Melbourne, Australia

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

From: John McCalpin <[email-masked]>
Date: Sat, 18 May 91 19:28:56 EDT
Subject: Very Fast Poisson Solvers

I am researching the finite-difference convergence of the time and
space integrated statistical properties of a set of equations that
approximate large-scale oceanic and atmospheric flows. I find myself
in need of a ridiculously fast solver for a Poisson-like equation that
arises at each time step.  The equation is the straighforward 5-point
finite difference approximation to:

		d^2     d^2
	     (	---  +  ---   - g^2 ) h(x,y) = f(x,y)
		dx^2    dy^2

subject to:
		h(0,y) = h(Lx,y) = h(x,0) = h(x,Ly) = 0.

with a uniform Cartesian finite-difference grid of a few hundreds
of grid points on a side.

(1) Does anyone out there have an extremely fast direct (FACR?)
or multigrid solver that is applicable to this problem?  (I am
currently using HWSCRT from FISHPAK).

(2) Are any "real" numerical analysts working on problems related
to the convergence of statistical measures of nonlinear hyberbolic
or nearly hyperbolic systems?

Thanks for any help....

John D. McCalpin			[email-masked]
Assistant Professor			[email-masked]
College of Marine Studies, U. Del.	J.MCCALPIN/OMNET

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

From: Philip Sterne <[email-masked]>
Date: 16 May 91 18:55:22 GMT
Subject: Vectorized Spherical Harmonics Routine

Can anyone point me to a vectorized Fortran routine for calculating
spherical harmonics? (Preferably Condon-Shortley phase, but that doesn't
matter so much).  I have a routine which computes the Ylm's using 
recursion to get the associated Legendre polynomials, but the recursion
slows it down considerably on vector machines.

Thanks,
		Phil

Philip Sterne                               [email-masked]
Lawrence Livermore National Laboratory      Phone   (415) 422-2510
Livermore,  CA 94550                        Fax     (415) 422-7300

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

From: Bernard Danloy <[email-masked]>
Date: Tue, 14 May 91 16:43:22 +0200
Subject: Iterative Method for Sparse Least Squares Problems

Several recent notes on NA-NET were concerned by sparse least squares problems;
the last one is the interesting summary of Tim Monks.

I am rather surprised that apparently nobody refers to a possible iterative
solution of the problem (at least, if the rectangular matrix has full rank).
I have myself current research under progress and would be very grateful to
learn more about recent advances. My personal work has been mainly theoretical
up to now but numerical experiments will be made during the next summer (some
test problems from the "real life" are very welcome) and a paper will be
published as soon as possible. Presently, the following result have been
obtained :
     1. It is quite possible to apply a "classical" conjugate-gradient method
	to the normal equations within an implicit approach (without computing
	the product of the matrix by its transposed) : the process converges
	mathematically in a finite number of steps.
     2. The above approach is numerically unstable but the instability has its
	origin in the implementation of the conjugate-gradient algorithm : the
	classical approach does minimize the number of arithmetic operations but
	is unstable if the residue does not converge to zero (this is obviously
	the case in the least squares problems). A new implementation has been
	developed which removes the numerical instability.
     3. New research is made in the direction of an algorithm which minimizes
	the error itself : in other words, if u is the unique exact solution
	of Ax=b ( if A is rectangular, u denotes the least squares solution ),
	we let e=x-u and we try to minimize (e|e) where ( | ) denotes the usual
	scalar product. Let us remember that, if A is square, symmetric and
	positive definite, the classical conjugate-gradient approach minimizes
	(e|Ae). My research is concerned by a so-called "minimal error" or
	"orthogonal directions" algorithm : some papers have been published
	that claim that such an approach is unstable and does not converge ;
	I did identify a basic error in the paper of Fletcher (Proc. Dundee
	1975) and in other papers refering to it. A new correct implementation
	is almost ready for testing. Remarks and suggestions about this are
	welcome.

Bernard DANLOY
Institut de Mathematique
University of Louvain-la-Neuve
Belgium

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

From: Dave Hill <[email-masked]>
Date: Mon, 13 May 91 10:45:53 EST
Subject: Computational Experiments for Numerical Analysis Instruction

                   Second Notice for Minisymposium

A minisymposium, "Computational Experiments for Numerical Analysis
Instruction", is being organized as part of the American Mathematical Society's
Eastern Section Meeting in Philadelphia. The meeting will be held at Temple
University Center City Campus on Saturday and Sunday, October 12 and 13, 1991.

The objective is to share instructional computational experiments that help
illuminate a topic in numerical analysis. The experiment can be a classroom
demonstration or a student laboratory assignment. The presentation could focus
on a particular technique, algorithm, or class of problems. Your discussion
should indicate the intended audience, the background in the course preceding
the experiment, tools (computer and/or software) required, options for
extensions, and relationships to other topics in your course.

Please interpret numerical analysis in a broad sense.

For consideration for participation in the minisymposium send a short
description of the experiment including the software and/or hardware required
to:

            Dr. David R. Hill
            Mathematics Department
            Temple University
            Philadelphia, Pa. 19122
            Email: [email-masked]
            Phone: 215-787-1654

Abstracts should be received by June 15, 1991. (No funds are available for
support of minisymposium participants. Overhead projectors will be available,
but computer projection capabilities are unknown at this time.)

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

From: Iain Duff <[email-masked]>
Date: Tue, 14 May 91 09:41:26 BST
Subject: Fox Prize, 1991

LESLIE FOX PRIZE 1991

One Day Meeting - Monday 24 June 1991
The University of Dundee, Scotland

The Adjudicating Committee (J C Mason, N K Nichols and C M Elliott) have
selected seven papers, from the twenty one entries that were submitted for the
1991 Leslie Fox Prize, to be presented by their authors at a meeting that will
be held in the Tower Building, University of Dundee on Monday June 24 starting
at 09.10. The submitted papers were once again of a very high standard and the
selection process was as difficult as ever.

You are cordially invited to attend this meeting at which you will hear some
of the best young numerical analysts talking about their research. The
selected authors, in the order of speaking (chosen randomly) are:

C J Budd (University of Bristol)

H Zha (Stanford University)

J Levesley (Coventry Polytechnic)

J F B M Kraaijevanger (University of Leiden)

B F Smith (Argonne National Laboratory)

J Xu (Pennsylvania State University)

P D Loach (University of Bristol)

A detailed programme is available from the Chairman of the Adjudicating
Committee, Professor J C Mason.

Through the hospitality of the Dundee group, no charges
will be made for tea or coffee, but attendees will be required to pay $6.00
for lunch - which will be arranged nearby in the University (bookings for
lunch will be needed by Monday June 17).

Many of those who plan to attend will also be staying on at the University of
Dundee for the Biennial Conference on Numerical Analysis (June 25 - 28). In
that case please inform the Conference organisers that you plan to attend
the Leslie Fox Prize Meeting first.

If you wish to attend the Leslie Fox Prize Meeting (and are not attending the
subsequent Conference) please contact Dr D F Griffiths, Department of
Mathematics and Computer Science, University of Dundee, Dundee, DD1 4HN,
([email-masked]). Those only attending the Fox Prize meeting will
normally be expected to arrange their own accommodation, but some accommodation
may be available at the University by booking through Dr D F Griffiths.

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

From: Frank Plab <[email-masked]>
Date: Tue, 14 May 91 10:04:33 BST
Subject: Parallel Numerical Analysis Workshop

                     CALL FOR PARTICIPATION
                        One-Day Workshop
                              on
                   PARALLEL NUMERICAL ANALYSIS
               
                          sponsored by 
               Edinburgh Parallel Computing Centre
                     University of Edinburgh
                          21 June 1991

A one-day workshop on Parallel Computing in Numerical Analysis will be
held at the Edinburgh Parallel Computing Centre (EPCC) on Friday, 
21 June 1991. The workshop should give numerical analysts and
other interested researchers an opportunity to exchange experiences in
parallelising numerical algorithms.

Invited presentations:

     Prof Iain Duff (Rutherford Appleton Laboratory) 
        "Exploitation of Parallelism in the Solution of Sparse Systems"
        
     Dr Peter Mayes (Numerical Algorithms Group)
        "Parallelism and the NAG library"

If you interested to give a talk and/or to attend please contact

     Frank Plab
     Edinburgh Parallel Computing Centre
     James Clerk Maxwell Building
     University of Edinburgh
     Mayfield Road
     Edinburgh EH9 3JZ
     Tel.: 031 - 650 5021
     Fax:  031 - 662 4712
     e-mail: [email-masked]
	
The Edinburgh Parallel Computing Centre (EPCC) is a multi-disciplinary
institution engaged in research and commercial development in parallel
computing.  It is home to a wide range of parallel computing equipment,
including: a Computing Surface with more than 400 T800 transputers and
over 300 users; the UK Grand Challenge machine, which contains 64
i860/T800 hybrid nodes; and both a 64x64 and a 32x32 AMT DAP.  EPCC has
a full-time staff of 26, and a large number of associates in computer
science, physical and mathematical sciences.

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

End of NA Digest
**************************
-------