During several years, important cooperations have been performed with top-class scientists mainly from USA and Europe, which have resulted in several joint publications (see the publication list for details). Normally, they have visited Umeå during one-to-four week periods, but also for extended visits. Below, a few examples that relate to our research are briefly summarized.

Since 2010, Bo Kågström is one of ten principal investigators in the Swedish Government's Strategic Research Program in eScience, named eSSENCE. Collaborations with our partners Lund University and Uppsala University are developing. Our research group is also associated with HPC2N and UMIT Research Lab at Umeå University.

Fred Gustavson, IBM T.J. Watson Research Center, Yorktown Heights is adjunct professor at the Dept. of Computing Science and HPC2N and spends regular visits in Umeå. The cooperation focuses on novel algorithms, techniques and HPC library software, including explicitly and recursive blocked algorithms and hybrid data structures. Software from our research has also been included in the IBM ESSL library.

Daniel Kressner was Emmy-Noether Fellow in our Umeå research group during 2005-07. Since then he has been at ETH and now professsor at EPF Lausanne. The collaboration started already during his PhD studies at TU Berlin (Volker Mehrmann supervisor) and has since then proceeded with focus on blocked and parallel algorithms for dense standard and generalized eigenvalue problems as well as structured and periodic counter parts in terms of formal matrix products. Recently, Kågström and Kressner appointed a new joint PhD student from Fudan University.

During 2009, we have (re)started cooperation with Paul Van Dooren, professor at Université Catholique de Louvain, Belgium, concerning the stratification of full rank polynomial matrices via the study of perturbations of linearizations. Earlier collaboration dates back to early 90’s.

Andras Varga, Senior Scientist, Institute of Robotics and Mechatronics, DLR, Oberpfaffenhofen, Germany is CACSD application specialist in the SSF project. The cooperation has been vital especially for our work in the analysis and design of periodic control systems.

Other visitors by our partners in NICONET (Numerics in Control Network, earlier funded by EU) include professor Volker Mehrmann, TU Berlin and Dr Vasile Sima, National Institute for Research & Development in Informatics, Bukarest.

Cooperation at Umeå univ. includes professor Anton Shiriaev and the Control Systems group. The focus has been on efficient and accurate structure exploiting numerical methods for solving Riccati periodic differential equations, which are essential in the design of periodic feedback controllers. This also includes collaboration with Andras Varga, DLR and Sergei Gusev, St. Peterburg State University.

In addition, for long time we are collaborating with and contributing to the LAPACK and ScaLACK projects (headed by professor Jim Demmel, Univerity of California, Berkeley and professor Jack Dongarra, Univ. of Knoxville; both have visited Umeå several times). The software from our RECSY and SCASY libraries and our new parallel QR and QZ algorithms will enable the same functionality in ScaLAPACK for very large scale dense eigenvalue problems as can be found in LAPACK today.

The results in our projects also build on fruitful collaborations with Jim Demmel, Berkeley (perturbation theory, algorithms and GUPTRI software for singular pencils with applications in CACSD), professor Alan Edelman, MIT (theory for versal deformations and stratifications for matrices and matrix pencil), professor Charles Van Loan, Cornell University (the GEMM-based approach for level 3 BLAS, blocked and parallel algorithms for matrix computations).

Ever since I started as a graduate student with Axel Ruhe as my supervisor, the late professor Gene Golub, Stanford University and the late professor Vera Kublanovskaya, LOMI St Petersburg have been invaluable sources of inspirartion, scientific mentors and dear personal friends. Regrettably, they are no longer with us!