**Today's Topics:**

- Information About Finite Element Software
- Numerical Solution of Time Delayed Differential Equations
- Large Dimensional Dynamic Models
- SLICOT, Software Library for Control Theory
- IMACS International Symposium on Iterative Methods in Linear Algebra
- Multigrid Short Course

From: Shirley Pomeranz <pomeranz@tusun2.mcs.utulsa.edu>

Date: Mon, 4 Mar 91 23:02:33 CST

I would like to know of any current surveys or articles describing

finite element software packages that are available. Anything

comparing different packages and discussing the particular field(s)

or engineering or mathematics discipline for which the software is intended

would be of interest to me.

Thank you for whatever information you can send my way.

Shirley Pomeranz

Assistant Professor

Mathematics

Department of Mathematical and Computer Sciences

The University of Tulsa

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From: Russell Van Gelder <vangeldr@cmgm.stanford.edu >

Date: 7 Mar 91 20:42:14 GMT

I am trying to model an oscillatory biochemical process and I have run into

difficulty due to time delays in the equations. Does anyone know of any

public domain algorithms for numerically integrating first order differential

equations with retarded arguments? The problem to be solved is an initial

value problem. An adaptation of fourth order Runge-Kutta would be especially

welcome - I have looked in most of the standard differential equation and

numerical methods books, but to no avail.

Russell Van Gelder vangeldr@cmgm.stanford.edu

Stanford Center for Molecular and Genetic Medicine - CMGM

Department of Biochemistry

Stanford University School of Medicine

Stanford, CA 94305

(415) 723-5871

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From: A. Scottedward Hodel <scotte@eng.auburn.edu>

Date: Fri, 8 Mar 91 13:17:20 CST

I am working on algorithms for the solution of large-dimensional

Lyapunov and algebraic Riccati equations. I have been testing

these algorithms on ``artificially'' constructed problems that meet

certain requirements, but I would like to test them on large

order models of physical systems (typically large, flexible

structures).

I am attempting to build a collection of large dimensional dynamic system

models of the form

d/dt x = A x + B u

y = C x

To date, the largest system I have been able to obtain is roughly 150th

order; they are typically half that size and are already in modal (block

diagonal) form. If anyone has or is aware of system models of larger order,

I'd very much like to obtain the system data.

Thanks!

Scotte

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From: Paul Van Dooren <vandooren@prlb.philips.be>

Date: Mon, 04 Mar 91 10:05:06 N

RELEASE OF THE NAG SLICOT LIBRARY

The Subroutine Library in COntrol Theory (SLICOT) is a collaborative

effort between the Numerical Algorithms Group (NAG) and the Benelux

Working Group on Software (WGS).

SLICOT is a library of FORTRAN 77 subroutines for control systems

analysis and design and consists of 68 user-callable routines

covering a wide range of applications areas within control theory.

Great care has been taken to build SLICOT on reliable and robust

algorithms. Wherever possible, numerical and statistical routines

from the NAG Fortran library are used. The SLICOT library can be run

on any machine using a Fortran 77 compiler. Source text (including

example programs) is provided. The current NAG price lies around

500 UKPounds for academic institutes and 1000 UKPounds for indutry.

A short description of the contents of the library is given below :

Utility routines (2 routines):

Printing real matrices and evaluating machine-dependent parameters

Mathematical routines (20 routines):

Basic linear algebra operations, linear equations, (total) least

squares, eigenanalysis, balancing, transformations to diagonal

bidiagonal and Hessenberg forms, Choleski decomposition,

matrix exponential

Transformation routines (18 routines):

Transformations from state-space to various canonical forms, to

transfer functions and polynomial matrix representation, from

polynomial matrix form to transfer matrix and vice-versa,

Markov parametrization from state-space and transfer matrix

Analysis routines (11 routines):

Reduction to minimal state space models, continuous to discrete,

interconnection of subsystems, dual forms, invariant zeros,

Hankel and Toeplitz expansion of multivariable sequences,

deadbeat control

Synthesis routines (9 routines):

Pole placement, algebraic Riccati equations, Lyapunov and

Sylvester equations, realisation methods, optimal control and

spectral factorization

Data Analysis (4 routines):

Convolution and deconvolution, forward and inverse Fourier

transform, anti-aliasing windowing

Filtering (4 routines):

Kalman filtering in different square root implementations

SLICOT is also a continuing effort. The WGS is responsible for

following the evolution of numerical algorithms in the area and

tries to complete the library in this respect (possibly by

inviting experts to contribute their software to the library).

A 2nd release is currently being produced and will contain

up to 20 new routines. In the future we also hope to be able

to include a chapter of nonlinear methods and adaptive control.

To obtain more information about SLICOT please reply to one of

the following addresses :

NAG c/o A. Brown WGS c/o R. Kool

Wilkinson House Eindhoven University of Technology

Jordan Hill Road Dept. Math. & Comp. Sc., DG 1.08

OXFORD P.O. Box 513

OX2 8DR NL-5600 MB Eindhoven

United Kingdom The Netherlands

Tel: +44 865 511245 Tel: +31 40 472374

Fax: +44 865 310139 Fax: +31 40 442150

NAGAAB@VAX.OXFORD.AC.UK WSCOLB@HEITUE5 (on BITNET)

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From: Pieter de Groen <pieter@tena2.vub.ac.be>

Date: Tue, 5 Mar 91 14:07:10 +0100

IMACS International Symposium on Iterative Methods in Linear Algebra.

Brussels Free Universities (ULB & VUB), April 2nd - 4th, 1991.

Aula VUB, Building Q, Pleinlaan 2 (Av. de la Plaine), B-1050 Brussels.

SCOPE:

The purpose of the symposium is to provide a forum for the

presentation and the discussion of recent advances in the analysis

and implementation of iterative methods for solving large linear

sytems of equations and for determining eigenvalues, eigenvectors

or singular values of large matrices.

TOPICS:

Matrix analysis: convergence acceleration - preconditioning -

methods for nonsymmetric, singular and

overdetermined systems - sparse eigenvalue problems

Boundary value problems:

multigrid methods - domain decomposition - spectral methods

Implementation techniques: on vector processors - on multiprocessors -

on massively parallel systems

Software developments: for sparse linear systems - for sparse

eigenproblems

Mathematical applications: partial differential equations - systems

theory - least squares problems

INVITED SPEAKERS:

A. van der Sluis

O. Axelsson

A. Yeremin

H. van der Vorst

D. Kincaid

E. Wachspress

F. Chatelin

SPECIAL SESSIONS (30 papers)

Coupled inner outer iteration methods, organized by O. Axelsson

Numerical methods for the analysis of Markov models,

organized by P. Courtois & G. Latouche.

Iterative solution of unsymmetric systems, organized by H. van der Vorst.

Spectral methods, organized by M. Deville & E. Mund.

The Lyapunov equation, organized by E. Wachspress.

Parallel and vector iterative methods, organized by D. Kincaid & C. Wu.

Complex variable methods for solving non-positive definite linear systems,

organized by M. Eiermann & W. Niethammer.

Sessions of Contributed Papers (45 papers)

Basic iterative methods

Eigenvalue Problems

Least squares and linear complementary problems

Methods for nonsymmetric systems

Mixed Hybrid Methods

Semiconductor device equations

Preconditioned conjugate gradients

Software Developments

Monte Carlo Methods.

The symposium is sponsored by the Belgian Fund for Scientific Research,

IBM and Honeywell.

The reception in the Brussels Town Hall is made possible by the

kind cooperation of the Brussels Mayor and Alderman.

The organising committee, Robert Beauwens and Pieter de Groen.

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

From: Gaoming Yang <ygaoming@copper.Denver.Colorado.EDU>

Date: Tue, 5 Mar 91 13:47:22 -0700

MULTIGRID SHORT COURSE

Information & Schedule

University of Colorado at Denver

March 25-29, 1991

Principal Lecturer: Achi Brandt

Supporting Lecturers: John Adams, William Briggs, Chaoqun Liu,

Steve McCormick, John Ruge

Short Course Chairman: Chaoqun Liu

Purpose: To provide an understanding of the principles and

procedures for multilevel methods, especially for partial

differential equations, including new multilevel approaches

in computational fluid dynamics.

Registration Fee: $500 (regular), $150 (student). Includes books

and other course materials, refreshments, and

computer lab access.

Topics:

. Basic tutorial

. Advanced methods for PDE's (including

multigrid procedures for general systems, nonlinearity,

ellipticity/nonellipticity, time dependence, inverse

problems, indefiniteness, discontinuities, singularities,

performance prediction/analysis, constrained optimization)

. Adaptive techniques (MLAT, FAC)

. Algebraic multigrid methods (AMG)

. Computational fluid dynamics (including finite volume element

methods, high Reynolds number flow, steady and unsteady

Navier-Stokes equations, Steady and unsteady Euler equations,

flow transition, and two-phase porous flow)

. Introduction to non-PDE multilevel techniques (including

integral and integro-differential equations, fast

dense matrix multiplication, many-body interactions,

direct solvers, large determinants, global discrete

highly-nonlinear optimization, and multilevel Monte Carlo

method in statistical physics).

For Further Information, Please Contact:

Chaoqun Liu

Computational Mathematics Group

University of Colorado at Denver

1200 Larimer Street, Campus Box 170

Telephone: (303) 556-4807 or (303) 556-4886

(e-mail: cliu@copper.denver.colorado.edu)

(e-mail: cliu@cudnvr.denver.colorado.edu)

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End of NA Digest

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