# News of the Research Group Computational Methods in Systems and Control Theory

## News (partly german)

## Preprint: An H2-Type Error Bound for Time-Limited Balanced Truncation

## Events: Peter Benner speaks at NYU and Temple University seminars

## New appointments: Petar Mlinaric appointed as GAMM Junior

## Events: GAMM Workshop on Applied and Numerical Linear Algebra

## Software: MORLAB 3.0

## Events: SciCADE 2017

## New appointments: Software: emgr - Empirical Gramian Framework 5.2

## CSC News: MaxNet on Big-Data-Driven Materials Science

## Preprint: Balanced truncation model order reduction in limited time intervals for large systems

## Events: PACO 2017

## CSC News: Software: emgr - Empirical Gramian Framework 5.1

## Events: METT VII - 7th Workshop on Matrix Equations and Tensor Techniques

## Events: 3rd Workshop on Model Reduction for Complex Dynamical Systems

## CSC News: Peter Benner re-appointed to SIMAX Editorial Board

## CSC News: Peter Benner appointed to ETNA Editorial Board

## Preprint: Combined Error Estimates for Local Fluctuations of SPDEs

## CSC News: Peter Benner appointed to the editorial board of ACOM

## Paper: ISI Highly Cited Paper

## CSC News: Software: emgr - Empirical Gramian Framework 5.0

## Events: Reduced Basis Summer School 2016

## Paper: Best practices for replicability, reproducibility and reusability of computer-based experiments exemplified by model reduction software

## Events: Wissenschaft im Rathaus

## Events: Chinese-German Workshop "Modelling, Model Reduction, and Optimization of Flows"

## Preprint: GMRES convergence bounds for eigenvalue problems

## Events: Workshop of GAMM activity group "Applied and Numerical Linear Algebra"

## Events: Computational Methods in Applied Mathematics (CMAM-7)

## Events: 7-th European Congress of Mathematics (TU Berlin)

## Events: 20th Conference of the International Linear Algebra Society (ILAS)

## Preprint: Best Practices for Replicability, Reproducibility and Reusability of Computer-Based Experiments Exemplified by Model Reduction Software

## Events: Invited talk at 6th Croatian Mathematical Congress

## Paper: Energy-Aware Solution of Linear Systems with Many Right Hand Sides

## Events: ECCOMAS Congress 2016

## Events: Computational Methods for High-Dimensional Problems

## CSC News: M-M.E.S.S 1.0.1 released

## CSC News: M-M.E.S.S 1.0 released

## CSC News: New Book: Index-aware Model Order Reduction Methods

*This is the first book on index-aware model order reduction methods. The splitting technique described in this book is computationally much more effective than existing methods Methods described for the reduction of algebraic systems are new and widely applicable*"

## Events:
**Open Access Day**

## CSC News: Former CSC PostDoc and Ph.D. student of P. Benner featured in Science Career

## Preprint: Balanced truncation model reduction for linear time-varying systems

## Preprint: A low-rank quadratic ADI algorithm for algebraic Riccati equations

## Events: Third Workshop on Model Reduction of Parametrized Systems

## Events: Matrix Equations and Tensor Techniques 2015

## New Paper: Optimal control and its application to inverse problems.

*Towards the identification of heat induction in chip removing processes via an optimal control approach*has been published in Volume 9, Issue 3 of the journal Production Engineering Research and Development. It covers a numerical method based on an optimal control ansatz for the solution of inverse heat conduction problems.

## Events: Workshop and meeting of GAMM activity group "Applied and Numerical Linear Algebra"

## Preprint: Frequency-Limited Balanced Truncation with Low-Rank Approximations

## Events: Workshop on Power-Aware Computing (PACO2015)

## Preprint: Inexact Low-Rank Newton-ADI Method for Large-Scale Algebraic Riccati Equations

## Events: Conference: Numerical Algebra, Matrix Theory, Differential-Algebraic Equations, and Control Theory

## CSC News:
**Matthias Voigt's PhD Defense**

*On Linear-Quadratic Optimal Control and Robustness of Differential-Algebraic Systemss*on Monday, May 4th.

## New Paper: Riccati-based Boundary Feedback Stabilization of Incompressible Navier-Stokes Flows

*Riccati-based Boundary Feedback Stabilization of Incompressible Navier-Stokes Flows*appeared in the 2nd issue of the 37th SISC volume on pages A832-A858. The article describes efficient numerical methods to compute a Riccati based feedback stabilization via boundary control input for incompressible Navier-Stokes equations.

## New Paper: Efficient solvers for matrix differential equations

*On the benefits of the LDL*will appear in volume 480 of the Elsevier journal Linear Algebra and its Applications. It covers efficient numerical methods for the solution of differential matrix equations.

^{T}factorization for large-scale differential matrix equation solvers## CSC News: Prof. H. Trentelman visiting Magdeburg

## New Paper: Optimal control and its application to inverse problems.

*Towards the identification of heat induction in chip removing processes via an optimal control approach*will appear in the journal Production Engineering Research and Development. It covers a numerical method based on an optimal control ansatz for the solution of inverse heat conduction problems.

## CSC News: New job posting

## Events: Student Krylov Day 2015

## CSC News:
**DAAD project "MINLP for damping optimization" for 2015-2016 approved**

## CSC News: New Funding

## New Publication: Optimal Control-Based Feedback Stabilization of Multi-field Flow Problems

## Preprint: Low-Rank Newton-ADI methods for Large Nonsymmetric Algebraic Riccati Equations

## Preprint: Balancing based model reduction for structured index-2 unstable descriptor systems with application to flow control

## Preprint: On GPU Acceleration of Common Solvers for (Quasi-) Triangular Generalized Lyapunov Equations

## CSC News: Workshop within DAAD project Optimal Damping of Vibrating Systems in Osijek (Croatia)

## Events: Workshop and meeting of GAMM activity group "Dynamics and Control"

## Preprint: On BLAS Level-3 Implementations of Common Solvers for (Quasi-) Triangular Generalized Lyapunov Equations

## Events: Peter Benner speaks at Heidelberg Laureate Forum

## Events: 3rd Symposium of the German SIAM Student Chapters

## CSC News: New article: Model Order Reduction for Systems with Moving Loads

## Preprint:
On the benefits of the LDL^{T} factorization for large-scale differential matrix equation solvers

^{T}based version of the standard low-rank Lyapunov solvers based on ADI or Krylov subspace methods. The method allows us to avoid complex arithmetic for the solution of matrix differential equations via higher order time integration methods, as well as the a priori reduction of the number of columns in the right hand side of the arising algebraic Lyapunov equations inside of the time integration loop.

## Preprint: Extending Lyapack for the Solution of Band Lyapunov Equations on Hybrid CPU-GPU Platforms

## Preprint: Semi-active damping optimization for vibrational systems using the parametric dominant pole algorithm

## Events: Joint GAMM ANLA and ALAMA Meeting 2014

## Events: Participation at the PMAA 2014 in Lugano

## Events: Householder Symposium XIX

## Events: Joint GAMM ANLA-MSIP Workshop 2014 -- Matrix Computations for Sparse Recovery

## Events: 85th Annual Meeting of the International Association of Applied Mathematics and Mechanics

## Events: Elgersburg Workshop, 3 - 6 March 2014

## CSC News: Opening workshop of the SIAM Student Chapter Magdeburg officially announced in SIAM News.

## CSC News: Max Planck Institute receives 50.000 Euro grant from Zeidler-Forschungs-Stiftung

## Preprint: FlexiBLAS: A flexible BLAS library with runtime exchangeable backends

## New Preprint: Numerical Solution of Eigenvalue Problems for Alternating Matrix Polynomials and Their Application in Control Problems for Descriptor Systems

## Events: Model Reduction of Complex Dynamical Systems 2013

## CSC News:
**Defense of Bachelor thesis by Björn Baran**

## CSC News:
**New group members**

## Preprint: Interfacing C-M.E.S.S. with Python

## Events: Numerical Solution of PDE Eigenvalue Problems

*Oberwolfach Leibniz Graduate Students (OWLG)*.

## Events: 3rd colloquium of SFB/TR-96 on 10/29-30/13 in Aachen

*SFB/TR-96*

## New Preprint:
L_{∞}-Norm Computation for Large-Scale Desriptor Systems Using Structured Iterative Eigensolvers

_{∞}-norms for descriptor systems using structured iterative eigensolvers. In particular, the algorithm computes some desired imaginary eigenvalues of an even matrix pencil and uses them to determine an upper and lower bound to the L

_{∞}-norm. We finally compare our method to a previously developed algorithm using structured pseudospectra. Numerical examples demonstrate the reliability and accuracy of the new method along with a significant drop in the runtime.

## Thesis Topic: Diplom/Master Thesis

*Structure-Preserving Balancing of Matrix Pencils Arising in Linear-Quadratic Optimal Control*

Balancing is a popular method to increase the accuracy when numerically computing the eigenvalues of a matrix. The aim of this work is the development of an algorithm that enables the balancing of even or skew-Hamiltonian/Hamiltonian matrix pencils by using structure-preserving transformations. This is necessary to be able to use structure-exploiting algorithms to compute the eigenvalues of the balanced pencils. The algorithm should be implemented in FORTRAN 77 and tested for some benchmark examples.

Contact: Matthias Voigt

## Thesis Topic: Diplom/Master Thesis

*Fast Numerical Computation of Structured Real Stability Radii for Large-Scale Matrices and Pencils*

Stability radii are a measure for the robustness of differential or differential-algebraic equations under perturbations. The goal of this project is to adapt existing methods in order to compute the structured real stability radius by using an optimization procedure over structured pseudospectra.

Contact: Matthias Voigt

## New Preprint: Peter Benner, Judith Schneider: Uncertainty Quantification for Maxwell's Equations Using Stochastic Collocation and Model Order Reduction

## New Preprint: Peter Benner, Patrick Kürschner, Jens Saak: Self-Generating and Efficient Shift Parameters in ADI Methods for Large Lyapunov and Sylvester Equations

## New Preprint:
P. Benner, A. Schneider:

Balanced Truncation for Descriptor
Systems with Many Terminals

The model reduction method introduced in [Benner, P. and Schneider, A.; *Balanced Truncation Model Order Reduction for LTI Systems with many Inputs or Outputs*, in A. Edelmayer: Proceedings of the 19th International Symposium on Mathematical Theory of Networks and Systems, 2010, ISBN/ISSN: 978-963-311-370-7] shows how to reduce linear time-invariant (LTI) continuous-time state space systems with either many inputs or many outputs using the well-known balanced truncation approach. We call this method balanced truncation for many terminals (BTMT). In this work we generalize BTMT to descriptor systems of the form

Eẋ(t) = Ax(t) + Bu(t), A, E ∈ ℝ^{n×n},B ∈ ℝ^{n×m}

y(t) = Cx(t) + Du(t), C ∈ ℝ^{p×n}, D∈ ℝ^{p×m},

where m ∈ 𝒪(n) and p ≪ n, or vice versa. We show how to obtain a reduced order model by solving one Lyapunov equation and using the Gauss-Kronrod quadrature to compute the needed projection matrices. In particular, we discuss the case when E is singular and show numerical results.

## New Preprint:
Eberhard Bänsch, Peter Benner, Jens Saak, Heiko Weichelt:

Riccati-Based Boundary Feedback Stabilization of Incompressible Navier-Stokes Flow

## Events: GMA activity group 1.30

## Events: 5th Workshop on Matrix Equations and Tensor Techniques

## Events: GAMM Workshop Applied and Numerical Linear Algebra

## Events: Workshop of the GAMM Activity Group ”Dynamics and Control Theory“

## New Preprint: FORTRAN 77 Subroutines for the Solution of Skew-Hamiltonian/Hamiltonian Eigenproblems - Part I: Algorithms and Applications

_{∞}-optimization, certain multi-body systems and many other areas in applied mathematics, physics, and chemistry. In these applications it is necessary to compute certain eigenvalues and/or corresponding deflating subspaces of these matrix pencils. Recently developed methods exploit and preserve the skew-Hamiltonian/Hamiltonian structure and hence increase reliability, accuracy and performance of the computations. In this paper we describe the corresponding algorithms which have been implemented in the style of subroutines of the Subroutine Library in Control Theory (SLICOT). Furthermore, we address some of their applications. We describe variants for real and complex problems with versions for factored and unfactored matrices S.

## New Preprint: FORTRAN 77 Subroutines for the Solution of Skew-Hamiltonian/Hamiltonian Eigenproblems - Part II: Implementation and Numerical Results

## Events: European Numerical Mathematics and Advanced Applications (ENUMATH) conference 2013

## Events: Preconditioning of Iterative Methods - Theory and Applications

*Preconditioning of Large-Scale Saddle Point Systems Arising in Riccati Feedback Stabilization of Coupled Flow Problems*at the PIM2013 in Prague (Czech Republic).

## New Preprint: Model order reduction of DAEs arising from the simulation of gas transport networks

## New Preprint: Fast Solvers for Cahn-Hilliard Inpainting

## New Preprint: A low-rank in time approach to PDE-constrained optimization

## Preprint: Numerical Solution of Large and Sparse Continuous Time Algebraic Matrix Riccati and Lyapunov Equations: A State of the Art Survey

## Events: Numerical Analysis and Scientific Computation with Applications

## CSC News:
**CSC at Preconditioning 2013**

## Events: European Conference on Computational Optimization 2013

## CSC News:
**New intern**

_{∞}-norm for descriptor systems of high dimension. The internship is funded by a grant from the

*DAAD RISE program*.

## CSC News:
**New intern**

_{2}model reduction of bilinear systems.

## Events: CIRM workshop Model Reduction and Approximation for Complex Systems

## Thesis Topic: Bachelor Thesis or Internship

Contact: Patrick Kürschner

## CSC News:
**New intern**

## New Preprint: Peter Benner, Patrick Kürschner: Computing Real Low-rank Solutions of Sylvester equations by the Factored ADI Method

## CSC News: New group member

## New Preprint: Melina Freitag, Patrick Kürschner: Tuned preconditioners for inexact two-sided inverse and Rayleigh quotient iteration

## CSC News:
**New student assistant and diploma candidate**

## CSC News:
**New student assistant and Bachelor candidate**

## Events: 84th Annual Meeting of the International Association of Applied Mathematics and Mechanics

## Events: Workshop on Numerical Methods for Optimal Control and Inverse Problems

*Riccati-Based Boundary Feedback Stabilization of Multi-Field Flow Problems*at the OCIP2013 in Garching by Munich (Germany).

## CSC News:
**Jonas Denißen visits J. J. Strossmayer University of Osijek in Croatia**

## Events: SPP1253 Final Meeting

## CSC News:
**New group member**

## CSC News: New Book: System-level Modeling of MEMS

## CSC News: Elgersburg Workshop, 11 - 14 February 2013

## CSC News: Zoran Tomljanović (J. J. Strossmayer University of Osijek) visiting CSC

## CSC News:
**New intern**

## Events: Meeting of the working group parameterization and simulation of SFB/TR-96 on 01/31-02/01/13 in Dresden

*SFB/TR-96*

## Events: 29th GAMM-Seminar Leipzig on Numerical Methods for Uncertainty Quantification

## New appointments:
**Jessica Bosch, Mian Ilyas Ahmad, Andrew Barker, Yao Yue join the CSC group**

## New Preprint: Jessica Bosch, Martin Stoll, Peter Benner: Fast solution of Cahn-Hilliard Variational Inequalities using Implicit Time Discretization and Finite Elements

## CSC News:
**DAAD project for 2013-2014 approved**

## Thesis Topic: Bachelor Thesis

Contact: Jens Saak

## Thesis Topic: Bachelor Thesis

Contact: Jens Saak

## Thesis Topic: Bachelor Thesis

Contact: Jens Saak

## Thesis Topic: Diplom/Master Thesis

Contact: Jens Saak

## Thesis Topic: Diplom/Master Thesis

Contact: Jens Saak

## Thesis Topic: Bachelor Thesis

Contact: Jens Saak

## Thesis Topic: Bachelor Thesis

Contact: Jens Saak

## Events:
**Scientific Network: Scale bridging simulation methods based on order-reduction and co-simulation, 10.-12. Dezember**

## New Paper: Efficient Model Order Reduction for Piezo Mechanical Systems

*Computation of a Compact State Space Model for an Adaptive Spindle Head Configuration with Piezo Actuators using Balanced Truncation*will appear in volume 6 issue 6 of the Springer journal Production Engineering Research and Development. It covers efficient numerical methods for the model order reduction of the resulting index 1 differential algebraic systems via balanced truncation.

## New Preprint:
Peter Benner, Patrick Kürschner, Jens Saak:

An Improved Numerical Method for Balanced Truncation for Symmetric Second Order Systems

## CSC News: Guests from TU Munich

## Events: 2nd colloquium of SFB/TR-96 on 10/24-25/12 in Chemnitz, Fraunhofer IWU

*SFB/TR-96*

## New Preprint:
Peter Benner, Jens Saak, Friedhelm Schieweck, Piotr Skrzypacz, Heiko K. Weichelt:

A Non-Conforming Composite Quadrilateral
Finite Element Pair for Feedback Stabilization of the Stokes Equations

## CSC News: Prof. Dr. Sebastian Schöps visiting CSC

## New Preprint: Fast Evaluation of Time-Harmonic Maxwell's Equations Using the Reduced Basis Method

## Events: Structured Matrix Computations in Non Euclidean Geometries: Algorithms and Applications

## Events: Second International Workshop on Model Reduction for Parametrized Systems (MoRePaS II)

## Open Position: Student Assistant

**This news entry is expired.**

## Events: Chemnitz FEM Symposium

## New Preprint: Fast Iterative Solution of Reaction-Diffusion Control Problems Arising from Chemical Processes

## Events: Workshop and meeting of GAMM activity group "Dynamics and Control"

## Events: DMV Annual Meeting 2012

*Deutschen Mathematiker Vereinigung*that takes place in Saarbrücken, Germany, from 17th til 20th of September 2012.

## Events: Kick-off meeting of the GAMM CSE activity group

## Events: 3rd IMA Conference on Numerical Linear Algebra and Optimisation

*3rd IMA Conference on Numerical Linear Algebra and Optimisation*which takes place in Birminham, UK, from 10th until 12th of September 2012.

## Events: XII GAMM Workshop on Applied and Numerical Linear Algebra

## Events: Workshop on Nonlinear Model Order Reduction (update)

## CSC News:
**Linux cluster otto now computing faster**

The cluster is supporting the work of all research groups at the institute. With its help many experiments and molecules can be simulated that would not have been doable on a standard workstation, or that would have require unacceptable execution times. The research group Computational Methods in Systems and Control Theory that is in charge of the device, is using the cluster to develop parallel numerical algorithms for model reduction and optimal control.

## New Team Members:
**Martin Redmann, Piotr Skrzypacz **

## New Visitor: John Pearson coming to Magdeburg for two months on ESF grant

## New Preprint:
Peter Benner, Jens Saak, Martin Stoll, Heiko Weichelt:

Efficient Solution of Large-Scale Saddle Point Systems Arising
in Riccati-Based Boundary Feedback Stabilization of Incompressible
Stokes Flow

## CSC News: Dr. Vasile Sima (National Institute for R&D in Informatics, Bucharest, Romania) visiting CSC

## Events: SIAM Applied Linear Algebra

## Open Position: Postdoctoral researcher

**This news entry is expired.**

## Open Position: Postdoctoral researcher/PhD Student

**This news entry is expired.**

## Open Position: Senior postdoctoral researcher/Team leader

**This news entry is expired.**

## Open Position: Student Assistant

**This news entry is expired.**

## Events:
**Workshop on Nonlinear Model Order Reduction**

## New visitor: Nick Higham visiting from Manchester

*Recent Progress in Matrix Functions*and the talk will be given on Thursday, April 26, 2012 at 5 pm here at the MPI. Nick is the Richardson Professor of Applied Mathematics and an expert on many things in Numerical Analysis with a particular focus on Numerical Linear Algebra as well as Numerical Software. He is the vice president of SIAM, a fellow of the Royal Society and SIAM fellow.

## New visitor: Jan Heiland visiting from TU Berlin

*Differential-algebraic Riccati Decoupling in Optimal Control of Flows*in the CSC Reading Group. Main reason for the visit is a projected collaboration with Jens Saak, Norman Lang and Heiko Weichelt.

## New visitor: Catherine Powell visiting from Manchester

*Efficient solvers for saddle point problems with random data*on Tuesday the 10th of April at 2pm. Catherine is an expert on Uncertainty Quantification with a particular focus on computational fluid dynamics.

## CSC News:
**Three Interns Working with CSC**

*DAAD WISE scholarship*will assist Jens Saak with his work. Furthermore, Peihong Jiang (University of Rochester (USA)) who received a grant from the

*DAAD RISE program*and Maximilian Bremer (University of Texas at Austin (USA)) will join Matthias Voigt.

## CSC News:
**MPCSC at GAMM Annual Meeting in Darmstadt**

## Events: 12th Copper Mountain Conference on Iterative Methods

*Efficient Solution of Large-Scale Saddle Point Systems Arising in Feedback Control of the Stokes Equations*there.

## CSC News: Elisabeth Ullmann visiting from University of Bath

*Numerical Methods for PDEs with Uncertainties*(21/03/11, 14:00).

## New Preprint:
Christine Nowakowski, Patrick Kürschner, Peter Eberhard, Peter Benner:

Model Reduction of an Elastic Crankshaft for Elastic Multibody Simulations

## Events: Workshop on Numerical Methods for Optimal Control and Inverse Problems

*Riccati-Based Boundary Feedback Stabilization of Incompressible Flow Problems*at the OCIP2012 in Garching by Munich (Germany).

## New Preprint: Tyrone Rees, Martin Stoll:A fast solver for an H1 regularized optimal control problem

## CSC News: New CSC-Group-Member

## New Preprint: Peter Benner, Thomas Mach: The LR Cholesky algorithm for symmetric hierarchical matrices

We will explain this behavior by applying a theorem on the structure preservation of diagonal plus semiseparable matrices under LR Cholesky transformations.

## Thesis Topic: Diplom/Master Thesis

*Kalman-Yakubovich-Popov Lemma for Algebraic Difference Equations*

In many fields of systems and control theory, dynamical systems are analyzed via certain rational matrix functions (so-called Popov functions). Properties of Popov functions can often be characterized via solvability of linear matrix inequalities. The aim of this thesis is the adaption of the existing theory to the case that the dynamical system is given as algebraic difference equation. Furthermore, relations to the structure of palindromic matrix pencils should be analyzed. Optionally, applications of the theory can be taken into account, e.g., for the structure analysis of dynamical systems or optimal control.

Contact: Matthias Voigt

## Thesis Topic: Bachelor Thesis

*Numerical Computation of Generalized Structured Pseudospectra*

For the analysis of the properties of matrices often their pseudospectra are considered. For the visualization of pseudospectra a MATLAB GUI has already been developed. For the graphical depiction of structured pseudospectra, a generalization of pseudospectra of matrices, such a tool does not exist. Therefore, the task of this thesis is to develop methods for the computation of structured pseudospectra and to implement these in MATLAB. In particular, different approaches for the acceleration of the computations should be analyzed.

Contact: Matthias Voigt

**This news entry is expired.**

## Thesis Topic: Bachelor/Diploma/Master Thesis

*Model reduction in complex biochemical networks*

An important tool in the analysis of complex physical phenomena is the simulation of the underlying mathematical models, which are often given by systems of ordinary and/or partial differential equations. As one is interested in models as accurate as possible, linear models are often insufficient such that one is faced with large-scale nonlinear systems. Frequently, these cannot be handled efficiently, necessitating model order reduction, i.e., the construction of a smaller system approximating the original one. In this thesis, a recently introduced approach for nonlinear model reduction should be implemented and tested by means of a real-life application arising in the context of biochemical reaction networks.

Contact: Tobias Breiten

## Thesis Topic:
**Bachelor Thesis**

Contact: Martin Stoll

## Thesis Topic: Bachelor Thesis

*Optimal Control of a second order partial differential equation with acceleration measurements.*Optimal control problems for infinite dimensional second order systems with acceleration measurements are in general ill-posed. Jacob and Morris proposed a method exploiting the actual implementation of the measurement that pulls the problem back to a well posed one. Here such a system is to be implemented and solved numerically.

Contact: Jens Saak

## Thesis Topic: Diplom/Master Thesis:

*Numerical solution of low-rank representations of band-limited Gramians*

In this thesis we investigate the representation of band-limited Gramians by matrix equations and the low-rank approximation of thereof.

Contact: Patrick Kürschner

## Thesis Topic: Bachelor Thesis

*Simultaneous iterative solution of the adjoint linear systems in the dual low-rank ADI iteration for Lyapunov equations*

Solving dual large-scale Lyapunov equations is a main step for carrying out balanced truncation model order reduction for linear, time-invariant control systems. Both Lyapunov equation can be solved simultaneously in one run of the dual low-rank ADI iteration. Here we are going to investigate the simultaneous iterative solution of the occurring adjoint linear systems with BiCG / QMR.

Contact: Patrick Kürschner

## New visitor: Bart Vandereycken visiting from EPFL

## CSC News: Hermann Mena visiting from ENP Quito

## New visitor: Michael Saunders visiting from Stanford

## CSC News: New CSC-Group-Member

## New Preprint: First MPIMD-preprint in 2012 published

## New Preprints: 3 Preprints in 5 Days

- Peter Benner, Tobias Breiten:
*On optimality of interpolation-based low-rank approximations of large-scale matrix equations* - Peter Benner, Martin Köhler, Jens Saak:
*Sparse-Dense Sylvester Equations in ℋ₂-Model Order Reduction* - Thomas Mach, Jens Saak:
*Towards an ADI iteration for Tensor Structured Equations*

## Events: Workshop on Matrix Equations and Tensor Techniques at RWTH Aachen

## New visitor:
**John Pearson visiting from Oxford**

*Preconditioned Iterative Methods for Optimal Control Problems*on Thursday the 17th at 3pm. He will also be working with Martin Stoll on the fast solution of nonlinear optimal control problems.

## CSC News:
**Philip Losse's PhD Defense**

*The ℋ*on Friday, 4th November. He will receive his degree from TU Chemnitz.

_{∞}Optimal Control Problem for Descriptor Systems## New visitor: Cosmin Ionita (Rice University) visiting

## Events: Summer School Numerical Linear Algebra for Dynamical and High-Dimensional Systems

*Summer School Numerical Linear Algebra for Dynamical and High-Dimensional Systems*will be held on October 10-15, 2011 in Trogir, Croatia and is organized by Peter Benner (MPI Magdeburg), Daniel Kressner (EPF Lausanne), Ninoslav Truhar (University of Osijek) and Zlatko Drmač (University of Zagreb).

## Events: 1. General Assembly of the DFG Transregio 96 at TU Dresden

*Thermo-energetic design of machine tools*meet at TU Dresden for their first general assembly. During the 2 days workshop the 19 participating subprojects present their current and future work for the first year of existence. Peter Benner, Norman Lang and Jens Saak will join as responsible for project A06 Model Order Reduction for Thermo-Elastic Assembly Group Models and establish contacts to the persons in charge of the other simulation projects.

## CSC News: New CSC-Group-Member

## Events: SPP1253 Anual Meeting

## Events: GAMM Workshop Applied Linear Algebra

## CSC News: New CSC-Group-Members

## New preprint: John Pearson, Martin Stoll, Andy Wathen: Regularization-robust preconditioners for time-dependent PDE constrained optimization problems

## Events: 17th ILAS Conference in Braunschweig

*Parallel Computing in Numerical Linear Algebra*. Further several group members will give contributed talks.

## CSC News: New CSC-Group-Member

## New visitor:
**Fikriye Yilmaz (Gazi University, Ankara) visiting**

## New preprint: Martin Stoll: One-shot solution of a time-dependent time-periodic PDE-constrained optimization problem

## Thesis Topic: Diplom/Master Thesis:

*Regulator based tracking control of a parabolic partial differential equation under control constraints*

We are searching for a regulator based feedback control u. Since this is not covered by the linear quadratic regulator approach, we first compute a reference pair of control and solution trajectory via open loop optimization. The resulting pair is then tracked by the regulator based feedback control.

Contact: Jens Saak

## Open Position: Student Assistant

**This news entry is expired.**

## Open Position: Student Assistant

**This news entry is expired.**

## Events: CSC-Aachen Workshop on parametric model order reduction

**5th of July 2011**, to discuss the latest developments and state-of-the art methods to generate accurate and efficient reduced models for problems coming from a variety of applications. The workshop is going to be held in our big seminar room and we invite you to join us for the whole day or parts of it.

For more information see the workshop webpage or contact Martin Stoll (stollm@mpi-magdeburg.mpg.de).

## CSC News: DFG funding Transregio 96

*Thermo-Energetic Design of Machine Tools*at Technical Universities Dresden and Chemnitz, as well as RWTH Aachen. The Chemnitz part of our research group is participating with project A06 Model Order Reduction for thermo-elastic assembly group models.

## Open position: Researcher/PhD Position (100%, Entgeltgruppe,13 TV-L)

**This news entry is expired.**

## CSC News: Dr. Vasile Sima (National Institute for R&D in Informatics, Bucharest, Romania) visiting CSC

## Thesis Topic: Diplom/Master Thesis

**This news entry is expired.**

## CSC News: Peter Benner and Martin Stoll at Householder Symposium XVIII

*Rational Krylov Subspaces for Nonlinear Model Reduction*. Martin Stoll will present a poster on

*Preconditioning for time-dependent optimal control problems*.

The Householder Symposia are one of the longest running conference series in applied mathematics and attendance is by invitation only. The first meeting goes back to 1961 in Gatlinburg and therefore, the first meetings were called

*Gatlinburg Conference*. The series was renamed in 1969 to honor Alston Householder for his groundbreaking contributions to Numerical Mathematics and is now held every 3 years.

## Events: 1-Day Symposium in Celebration of Danny Sorensen's 65th Birthday

*Eigenvalues, Model Order Reduction and Trust Regions*in celebration of Danny Sorensen's 65th birthday. The symposium will be held in Reno, Nevada.

## New Preprint: Peter Benner, Tobias Breiten: Interpolation-Based ℋ₂-Model Reduction of Bilinear Control Systems

## New preprint: Martin Stoll, Andy Wathen (Oxford): All-at-once solution of time-dependent Stokes control

## Open Position: Student Assistant

**This news entry is expired.**

## Events: 6th Science Night in Magdeburg

**Saturday, 28th May 2011, 6.00 a.m. to 1.00 p.m., Max Planck Institute Magdeburg**

We cordially invite you and your family to discover basic research in the engineering sciences: during guided tours through our institute, short lectures on our research topics and in experiments for kids and grown-ups! Our program for you (in German) ...

## CSC News: Linux-Cluster Otto in the Press

## Events: Registration for Summer school in Croatia now open

*Summer School Numerical Linear Algebra for Dynamical and High-Dimensional Systems*is now open until June 30. The school will be held on October 10-15, 2011 in Trogir, Croatia and is organized by Peter Benner (MPI Magdeburg), Daniel Kressner (EPF Lausanne), Ninoslav Truhar (University of Osijek) and Zlatko Drmač (University of Zagreb).

## CSC News: Minisymposium at SIOPT 2011

*Preconditioning in PDE-Constrained Optimization*at the SIAM Conference on Optimization, which takes place from May 16 until May 19, 2011, in Darmstadt. Peter Benner gives a talk in the minisymposium

*Model Order Reduction Techniques in PDE Constrained Optimization*on

*System-theoretic Methods for Model Reduction of Linear and Nonlinear Parabolic Systems*, too.

## CSC News:
**Daniel Kressner visiting**

*Low-rank tensor techniques for parametrized and high-dimensional linear algebra problems*in the MPI Colloquium on the

**12th of May**. Daniel is an expert on many things in numerical linear algebra such as tensor techniques and eigenvalue problems.

## CSC News:
**David Knezevic visiting**

*The Certified Reduced Basis Method: Real-time Simulation of Parametrized Systems*(05/09/11, 15:30).

## Events: 1. Max Planck Industrial Workshop – Bridging the gap between basic research and industrial application

*Friday, May 6th, 2011, 9.00 a.m. to 1.00 p.m.*, Max Planck Institute Magdeburg We would like to discuss with you how to enhance cooperation between fundamental research and industrial application, looking at projects which are being pursued jointly between research groups of the Max Planck Institute Magdeburg and external partners from industry. Invitation and program (in German) ...

## CSC News:
**Melina Freitag visiting**

*Preconditioned inverse iteration and shift-invert Arnoldi method*(05/03/11, 15:00).

## CSC News:
**Jens in Osijek, Croatia**

*Algebraic Riccati Equations*from May 2 to 06. Additionally he give a colloquiums talk at 5th May on

*Numerical Solution of Linear Quadratic Regulator Problems under PDE Constraints*.

## CSC News:
**4 Contributed Talks at GAMM Annual Meeting in Graz**

## CSC News: Hermann Mena visiting

## CSC News:
**First CSC research group weekend workshop**

## CSC News: Timo Reis visiting CSC

*Infinite-Dimensional Systems and Balanced Truncation*on March 23th, 10:00 (V1.06).

## New Preprint: Peter Benner, Thomas Mach: The preconditioned inverse iteration for hierarchical matrices

We extend the ideas to the computation of inner eigenvalues by computing an invariant subspaces S of (M-\mu I)² by subspace preconditioned inverse iteration.

## CSC News: Prof. Peter Benner awarded with Honorary Professorship

## CSC News: Project Meeting

## CSC News: MoreSim4Nano project cooperation gets started

## Events: MOR2011

## CSC News: New CSC-Group-Members

## Events:
**Verteidigung Diplomarbeit**

*Feedback-Stabilisierung von instationären, inkompressiblen Strömungen mit Riccati-Ansatz*in Chemnitz im Raum 2/B202.

## Events:
**Verteidigung Diplomarbeit**

*H*in Chemnitz im Raum 2/41/638.

_{2}Modellreduktion Verfahren-Implementierung-Vergleich## New Preprint:
Peter Benner, Thomas Mach: Computing all or some Eigenvalues
of symmetric ℋ_{ℓ}-Matrices

_{ℓ}-matrix M. The bisection method requires matrix-size independent many iterations to find an eigenvalue up to the desired accuracy, so that an eigenvalue can be found in linear-polylogarithmic time. Numerical experiments demonstrate the efficiency of the algorithm, in particular for the case where some interior eigenvalues are required.

## CSC News:
**New CSC Webpage**

## Events: CSC Welcome Colloqium

## CSC News: New position

**Computational Methods in Systems and Control Theory (CSC)**. Additionally, he will also keep the "Mathematics in Industry and Technology" professorship in Chemnitz on an extraofficial basis.

Most of the MiIT group has moved to Magdeburg, too.