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ALOP Colloquium with Prof. Andreas Frommer

May 15 / 16:00 - 18:00





On Monday, May 15 2017,   Prof. Andreas Frommer of Bergische Universität Wuppertal will join the ALOP-Colloquium and present his recent work entitled

 

Matrix functions – computation and convergence for Krylov subspace based methods

Abstract: f(A)b, the action of the function f of a matrix A on a vector b, is required in many applications, for example in exponential integrators, where f = exp or in lattice QCD where f(z) = z- α; α ϵ (0, 1). Typically, A is large and sparse, so computing f(A) directly is not possible, but subspace techniques allow to approximate f(A)b. In this talk will address issues related to the computation and to the
convergence analysis for Krylov subspace based methods. The outstanding problem in computation is how to obtain a stable restart procedure, and we show how this can be achieved when f can be adequately represented by a contour integral. On the analytical side, we present convergence results when f is a Stieltjes function and A is symmetric and positive de nite and, with appropriate modi cations, when A is just positive de nite but not necessarily symmetric. Finally, we will address generalizations to the block case, i.e. when several vectors b are to be treated simultaneously.

The presentation will take place in HS 9

We will meet over coffee in E10 at 15:45

Details

Date:
May 15
Time:
16:00 - 18:00
Event Category:

Organizer

Research Training Group ALOP at Trier University
Phone:
0651-2013461
Email:
alop@uni-trier.de

Venue

Trier University E Building
Universitätsring 15
Trier, 54296 Germany
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