Scientific Computing Seminar

Date and Place: Thursdays and hybrid (live in 32-349/online via Zoom). For detailed dates see below!


In the Scientific Computing Seminar we host talks of guests and members of the SciComp team as well as students of mathematics, computer science and engineering. Everbody interested in the topics is welcome.

List of Talks

Event Information:

  • Thu

    SC Seminar: Ralf Zimmermann


    Prof. Ralf Zimmermann, Department of Mathematics and Computer Science (IMADA), University of Southern Denmark (SDU), Denmark

    How to interpolate low-rank matrix decompositions? Computing the Riemannian normal coordinates in the space of orthogonal frames


    We address the problem of computing Riemannian normal coordinates on the real, compact Stiefel manifold of orthogonal frames. The Riemannian normal coordinates are based on the so-called Riemannian exponential and the Riemannian logarithm maps and enable to transfer almost any computational procedure to the realm of the Stiefel manifold. To compute the Riemannian logarithm is to solve the (local) geodesic endpoint problem.

    In this talk, we present efficient matrix-algorithms for solving the
    geodesic endpoint problem on the Stiefel manifold for a one-parameter
    family of Riemannian metrics. The findings are illustrated by numerical experiments. We use the Riemannian normal coordinates to construct interpolated matrix curves, where the sample data matrices stem from the thin, (truncated) singular value decomposition and the compact QR-decomposition, respectively.

    How to join

    The talk is held online via Zoom. You can join with the following link: