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Bo Kågström

Related publications (9)

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Algorithm 953: Parallel Library Software for the Multishift QR Algorithm with Aggressive Early Deflation

Daniel Kressner, Meiyue Shao, Bo Kågström

Library software implementing a parallel small-bulge multishift QR algorithm with Aggressive Early Deflation (AED) targeting distributed memory high-performance computing systems is presented. Starting from recent developments of the parallel multishift QR ...

Assoc Computing Machinery2015

A generalized matrix product can be formally written as Lambda(sp)(p) Lambda(sp-1)(p-1) ... Lambda(s2)(2) Lambda(s1)(1) where s(i) is an element of {- 1,+ 1} and ( A(1), ..., A(p)) is a tuple of ( possibly rectangular) matrices of suitable dimensions. The ...

International Linear Algebra Society2011

A Novel Parallel QR Algorithm For Hybrid Distributed Memory HPC Systems

Daniel Kressner, Bo Kågström

A novel variant of the parallel QR algorithm for solving dense nonsymmetric eigenvalue problems on hybrid distributed high performance computing systems is presented. For this purpose, we introduce the concept of multiwindow bulge chain chasing and paralle ...

2010

A parallel algorithm for reordering the eigenvalues in the real Schur form of a matrix is presented and discussed. Our novel approach adopts computational windows and delays multiple outside-window updates until each window has been completely reordered lo ...

2009

Blocked algorithms for the reduction to Hessenberg-triangular form revisited

Daniel Kressner, Bo Kågström

We present two variants of Moler and Stewart's algorithm for reducing a matrix pair to Hessenberg-triangular (HT) form with increased data locality in the access to the matrices. In one of these variants, a careful reorganization and accumulation of Givens ...

2008

A parallel Schur method for solving continuous-time algebraic Riccati equations

Daniel Kressner, Bo Kågström

Numerical algorithms for solving the continuous-time algebraic Riccati matrix equation on a distributed memory parallel computer are considered. In particular, it is shown that the Schur method, based on computing the stable invariant subspace of a Hamilto ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2008

Computing periodic deflating subspaces associated with a specified set of eigenvalues

Daniel Kressner, Bo Kågström

We present a direct method for reordering eigenvalues in the generalized periodic real Schur form of a regular K-cyclic matrix pair sequence (A k ,E k ). Following and generalizing existing approaches, reordering consists of consecutively computing the sol ...

2007

Multishift variants of the QZ algorithm with aggressive early deflation

Daniel Kressner, Bo Kågström

New variants of the QZ algorithm for solving the generalized eigenvalue problem are proposed. An extension of the small-bulge multishift QR algorithm is developed, which chases chains of many small bulges instead of only one bulge in each QZ iteration. Thi ...

Society for Industrial and Applied Mathematics2006

Reordering the eigenvalues of a periodic matrix pair with applications in control

Daniel Kressner, Bo Kågström

Reordering the eigenvalues of a periodic matrix pair is a computational task that arises from various applications related to discrete-time periodic descriptor systems, such as pole placement or linear-quadratic optimal control. However, it is also implici ...

IEEE2006