NA Digest Saturday, November 29, 2003 Volume 03 : Issue 48

Today's Editor:
Cleve Moler
The MathWorks, Inc.

Submissions for NA Digest:

Mail to

Information via e-mail about NA-NET: Mail to


From: Maher Moakher <>
Date: Thu, 27 Nov 2003 09:19:12 +0100
Subject: Solution to Ricatti Equation

This is a response to the question by Zhizhou Wang that was posted in
the NA Digest V. 03, #45.

The SPD solution to the Ricatti equation XAX = B is given by
the "geometric mean" of the matrices A and B. It is given
explicitely by any of the equivalent six expressions:

X = A(A^{-1} B)^{1/2}
= B(B^{-1} A)^{1/2}
= (B A^{-1})^{1/2} A
= (A B^{-1})^{1/2} B
= A^{1/2} (A^{-1/2} B A^{-1/2})^{1/2} A^{1/2}
= B^{1/2} (B^{-1/2} A B^{-1/2})^{1/2} B^{1/2}

When A and B commute, it reduces to (A B)^{1/2}.

Here are some references to the geometric mean of SPD matrices:

W. N. Anderson and G.E. Trapp, "Shorted operators", SIAM J. Appl. Math.,
28 (1975), pp. 60--71.

J. D. Lawson and Y.Lim, "The geometric mean, matrices, metrics and
more", Amer. Math. Monthly, 108 (2001), pp. 797--812.

M. Moakher, "A differential geometric approach to the geometric mean of
symetric positive-definite matrices", submitted to SIAM J. Matrix Anal.
Appl., 2003.


From: Daniel Stewart <>
Date: Tue, 25 Nov 2003 17:29:09 -0000
Subject: New Book, Numerical Methods for Image Registration


Numerical Methods for Image Registration
Jan Modersitzki, Institute of Mathematics, University of Lubeck

Based on the author's lecture notes and research, this well-illustrated and
comprehensive text is one of the first to provide an introduction to image
registration with particular emphasis on numerical methods in medical

For more information:


From: Jeremy Levesley <>
Date: Tue, 25 Nov 2003 13:02:24 +0000 (GMT)
Subject: Will Light Memorial Conference

The Will Light Memorial Conference

Professor Will Light, of the University of Leicester, died on December 8th 2002.
The Will Light Memorial Conference, on December 18th and 19th 2003, brings
together a number of Will's collaborators and friends, in a conference to
celebrate Will's life and work.

On December 18th, Jeremy Levesley, friend and colleague of Will's at Leicester,
will talk about Will's contribution to approximation theory. December 19th sees
the main part of the conference. The following speakers will talk on topics that
Rick Beatson, Canterbury, New Zealand.
Rob Brownlee, Leicester, England
Manfred Von Golitschek, Wuerzburg, Germany.
Tim Goodman, Dundee, Scotland
George Phillips, St Andrews, Scotland
Robert Schaback, Goettingen, Germany.

For more information, see

-- Jeremy


From: Chaoqun Liu <>
Date: Wed, 26 Nov 2003 17:36:28 -0600 (CST)
Subject: Conference in Melbourne on Computational Techniques and Applications

CTAC 2004
The 12th Biennial
Computational Techniques and Applications
Conference and Workshops
September 27 - October 1, 2004
The University of Melbourne
Melbourne, Victoria, Australia

Contributed papers are currently being sought in the areas of
computational mathematics; development and application of numerical
algorithms; numerical modelling of scientific, technical and
industrial applications; high performance computing; and other
aspects of the computational sciences for presentation at the

The conference program will include keynote addresses from the
following Invited Speakers:

Prof. Gary Leal, University of California at Santa Barbara
(Computational Studies in Materials Research)

Prof. Mark Cross, University of Greenwich
(Perspective on the current status of CFD)

Prof. Kevin Burrage, The University of Queensland
(Models for Genetic Regulation and their Simulation)

Dr Robert Anderssen, CSIRO
(Inverse Problems)

Prof. Chaoqun Liu, University of Texas at Arlington
(High Performance Computation for DNS/LES)

Immediately following the three days (27-29 September) of invited and
contributed presentations there will be two days of workshops
(September 30 - October 1). The topics for the CTAC 2004 workshops
and contact information for their respective conveners are:

Complex Fluids - Malcolm Davidson <>
Dispersed multiphase flows - Jiyuan Tu <>
High performance computing - Bill Appelbe <>
Molecular simulation - Steve Carnie <>

Further information, including registration information, the
registration form, and information on submitting abstracts, etc. is
available from the conference website:

This site is continually updated as further information on CTAC 2004
becomes available.

If you have any questions regarding CTAC 2004, please contact:

Conference Management
Old Physcis Building
The University of Melbourne
Victoria, Australia
Phone: +61 3 8344 6389
Fax: +61 3 8344 6122


From: Nathalie Revol <>
Date: Fri, 28 Nov 2003 15:56:21 +0100 (CET)
Subject: Special issue of Theoretical Computer Science

Special issue: Real Numbers and Computers

Guest editors: Marc Daumas and Nathalie Revol.

IMPORTANT DATES (tentative planning):
- Deadline for submissions of manuscripts: January 5th, 2004
(full papers only; extended abstracts will be rejected)
- Notification of acceptance/rejection: April, 2004
- Deadline for reception of final papers: July, 2004
- Parution: beginning of 2005

Efficient manipulation of real numbers in computers is still a
challenge. Many interesting theoretical and algorithmic problems are
linked with that topic and belong to quite distant fields such as
computer science, number theory, numerical analysis, computer algebra
and logics. A number of TCS special issues on real numbers and
computers has previously appeared (162 (1), 210(1), 279 (1-2) and 291
(2)), as follow-up to the RNC meetings on these topics. The last
meeting was RNC5 which took place in Lyon in September 2004, cf:

Scientists working on questions related to real computer arithmetic
are encouraged to present the theoretical or algorithmic aspects of
their results, even if they did not attend the RNC5 conference. Survey
and tutorial articles may be suitable if clearly identified as
such. Topics include (but are not restricted to) the following list:
- any computational number system
- implemented by a software package or in hardware,
- floating and fixed point,
- serial, on line arithmetic,
- continued fractions,
- exact computations,
- multiple precision,
- interval and stochastic arithmetics.

Please find additional information at


From: Hailiang Liu <>
Date: Wed, 26 Nov 2003 13:01:53 -0600
Subject: Faculty Position at at Iowa State University

The Department of Mathematics at Iowa State University has tenure track
positions open in the area of Numerical analysis and scientific computing.
These positions can be filled at the assistant professor or associate
professor level, depending on the experience of the candidates, please see
for details of the positions and how to apply. To guarantee consideration,
application must be received by January 15, 2004.


From: Jeff Borggaard <>
Date: Sun, 23 Nov 2003 12:25:12 -0500
Subject: Faculty Positions at Virginia Tech

Faculty Positions in Computational Sciences at Virginia Tech:

Virginia Tech has embarked upon a major interdisciplinary initiative in the
computational sciences with the development of a state-of-the-art terascale
computing facility that is ranked among the top supercomputers in the world.
As the next step, the University is now seeking to hire approximately 12
tenure-track faculty in the Colleges of Science and Engineering. As part of
this initiative, the Virginia Tech Department of Mathematics invites
applications for positions in the broadly defined area of computational
science at either the junior or senior levels. Successful candidates must
show evidence of participation in multidisciplinary research efforts, will
be expected to establish an internationally recognized, and externally
funded research program and to participate in teaching at both the graduate
and undergraduate levels.

Applicants should submit a curriculum vitae and candidate statement detailing
a brief description of research plans online at

Arrange for four letters of support to be sent to: Jeff Borggaard, Chair,
Computational Sciences Search Committee, Department of Mathematics, Virginia
Tech, Blacksburg, VA 24061. Applicants at the senior level should also
mail five selected publications, a record of funding and a description
of their previous multidisciplinary research projects to this address.

Applications will be considered beginning December 15, 2003. Virginia Tech
is an AA/EEO employer; applications from members of underrepresented groups
are especially encouraged.


From: Leslie Foster <>
Date: Mon, 24 Nov 2003 17:03:51 -0800
Subject: Faculty Positions at San Jose State University

Two tenure-track positions
Rank Assistant/Associate Professor

Candidates must have a Ph.D. in Mathematics, Applied Mathematics or
Statistics by August 2004. All areas accepted; statistics and applied
mathematics, including numerical analysis, especially welcome. Position
involves teaching undergraduate and graduate courses, advising Master's
theses, maintaining scholarly activity, and performing committee work.
Successful candidates must be prepared to teach a population of great
diversity in age, cultural background, ethnicity, primary language and
academic preparation. Salary commensurate with qualifications and

Send cover letter, CV, graduate transcript, teaching statement,
research statement, and three references by January 15, 2004 to:

Recruitment Committee
Department of Mathematics
San Jose State University
One Washington Square
San Jose, CA 95192-0103

See for more information.


From: Darlinda Dabor <>
Date: Mon, 24 Nov 2003 13:28:49 -0500
Subject: Postdoctoral Position at Rensselaer Polytechnic Institute

Department of Mathematical Sciences

Rensselaer Polytechnic Institute is pleased to announce the availability of
a postdoctoral position in applied mathematics and/or mechanical engineering
with emphasis on the theoretical results and/or algorithm development for
elastography problems. This position is anticipated to begin as soon as
possible but could start as late as February 2004. The position is for one
year, renewable for an additional year. Travel support to attend conferences
will be provided.

Applicants should send a letter of application, a curriculum vita, a
description of research interests, and three letters of recommendation sent
directly to: Alice Baker, Department of Mathematical Sciences, Rensselaer
Polytechnic Institute, 110 8th Street, Troy, NY 12180. Inquiries should be
sent to Professor Joyce McLaughlin ( or Professor Antoinette
Maniatty (

Review of applications will begin one month after the posting of this
announcement and will continue until the position is filled.

Rensselaer is an Equal Opportunity/Affirmative Action Employer. Women and
Minorities are strongly encouraged to apply.


From: Craig Douglas <>
Date: Wed, 26 Nov 2003 11:16:34 -0500
Subject: Postdoctoral Position at the University of Kentucky

The Center for Computational Sciences and Computer Science Department at
the University of Kentucky has one or more openings for Post-doctoral
Research Associates, funded by an NSF grant on dynamic data driven simulation
for wildfire modeling. This is a joint project with the National Center on
Atmospheric Research, University of Colorado at Denver, Texas A&M University,
and Rochester Institute of Technology. The associate will work with Professor
Craig Douglas and his group.

The appointments are possible for one or two years. An associate should
have a solid background and a research record in one or more of the
following areas:

- Physical modeling by partial differential equations
- Discretization techniques
- Physical or mathemtical model changing due to data injection
- Grid or parallel computing with results rendered on a wide variety of devices
- Analysis of ensemble computing

The associate should have a demonstrated ability to create parallel programs
on small SMPs, and will be expected to direct the programming work of one or
more graduate students. Ability to work with legacy numerical codes in Fortran
is required.

To apply, please send your CV including publications and experience in
software development, and have three letters of recommendation sent to
Craig Douglas <>.

Review of applications begins immediately and will continue until the
positions are filled.

The University of Kentucky is an equal opportunity/affirmative action
employer, and especially encourages applications from women and minorities.


End of NA Digest