Seminar Details:

**LANS Informal Seminar***"An "energy norm" for nonsymmetric problems with application to algebraic multigrid"*

DATE: July 20, 2011

TIME: 15:00:00 - 16:00:00

SPEAKER: James Lottes, *University of Oxford*

LOCATION: Bldg 240 Conference Center 1404-1405, Argonne National Laboratory

**Description:**

Problems governed by linear operators that are symmetric positive definite (SPD) enjoy a natural association with an energy norm, which finds many uses both in analysis and application. For example, Galerkin discretizations are optimal in the energy norm (a consequence of Cea's lemma), as is the conjugate gradient iteration. In the first part of this talk I will discuss a generalization of the energy norm to nonsymmetric operators. In the second part I will discuss how these ideas enable the convergence analysis of alebraic multigrid for SPD matrices, where the usual energy norm features heavily, to be generalized to the nonsymmetric case.

Please send questions or suggestions to Debojyoti Ghosh: ghosh at mcs dot anl dot gov.