Diplomanden- und Doktorandenseminar
Numerische Mathematik WS 2004/05

Dozenten: Matthias Bollhöfer, Christian Mehl, Volker Mehrmann, Reinhard Nabben, Caren Tischendorf, Harry Yserentant
Koordination: Christian Mehl
LV-Termine:Do 10:00-11:00 oder Do 10:00-12:00 in MA 313
Inhalt: Vorträge von Diplomanden, Doktoranden, Postdocs und manchmal auch Gästen zu aktuellen Forschungsthemen

Vollständige vorläufige Terminplanung:
Datum Uhrzeit Raum Vortragende(r) Titel
Do 21.10.2004 10:00 MA 313
  im An-
MA 313
Timo Reis Infinite dimensional descriptor systems
Do 28.10.2004 10:00 MA 313
Petr Tichy Towards understanding the convergence of GMRES (Abstract)
Do 11.11.2004 10:00 MA 313
Christian Schröder
The Riccati method for solving standard eigenvalue problems
  im An-
MA 313
Lena Wunderlich Numerical Solution of Second Order Differential-Algebraic Equations
Do 25.11.2004 10:00 MA 313
Andreas Zeiser Fundamentals of phonon-induced relaxation of hot electrons
  im An-
MA 313
Christian Otto Restarting the Second-Order Arnoldi Method and Restarting and Locking the Quadratic Jacobi-Davidson Method
Do 9.12.2004 10:00 MA 313
Michael Schmidt Model reduction via the discretization of input-output mappings
Do 16.12.2004 10:00 MA 366
Falk Ebert Electrical Circuits in a Nutshell -- Part 1: Currents and Flows
  im An-
MA 366
Simone Bächle Electrical Circuits in a Nutshell -- Part 2: Circuits and Graphs
Do 20.1.2005 10:00 MA 313
Britta Leupold Stability of Linear ODEs
Do 27.1.2005 10:00 MA 313
Sonja Schlauch Simulation of the flow in a stirred tank using Featflow
  im An-
MA 313
Ulrike Baur Factorized solution of Sylvester equations
Do 3.2.2005 10:00 MA 313
Caren Tischendorf Stability preserving integration of DAEs
Do 10.2.2005 10:00 MA 313
Christian Mense Coarsing Strategies for Algebraic Multigrid Methods

Interessenten sind herzlich eingeladen!

Weitere Vorträge siehe auch:


Abstracts zu manchen Vorträgen:

Petr Tichy (TU Berlin)
Worst-case GMRES for normal matrices and Jordan blocks
Do 28.10.2004, 10:00 Uhr in MA 313

Understanding the convergence behavior of the GMRES method for solving linear algebraic systems has been a challenging research topic for the last two decades. In this talk we present recent results on the algorithm's behavior for systems with normal coefficient matrices as well as for systems with a single Jordan block. We concentrate on the worst-case behavior of the GMRES residual norm.

For normal matrices, the worst-case behavior is described by a min-max approximation problem on the discrete set of the matrix eigenvalues. We will discuss how to evaluate or estimate this min-max approximation, and if it is possible to characterize the GMRES-related quantities that lead to the worst-case behavior.

For nonnormal matrices, the situation is more complicated. In general, no sharp bound in the GMRES residual norms is known, that depends on properties of the matrix only . However, in many cases the worst-case GMRES behavior is characterized by the so-called ideal GMRES approximation problem, introduced by Greenbaum and Trefethen. Evaluation or estimation of this ideal GMRES approximation in general still represents an open problem. We investigate this problem for a Jordan block, the prototype of a nonnormal matrix.

Impressum Christian Mehl 28.10.2004