SCHEDULE: NOV 10-16, 2012
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A Parallel Two-Level Preconditioner for Cosmic Microwave Background Map-Making
SESSION: Numerical Algorithms
EVENT TYPE: Papers
TIME: 1:30PM - 2:00PM
SESSION CHAIR: Costas Bekas
AUTHOR(S):Laura Grigori, Radek Stompor, Mikolaj Szydlarski
ROOM:355-EF
ABSTRACT:
In this work we study performance of two-level preconditioners in the context of iterative solvers of the generalized least square systems, where the weights are assumed to be described by a block-diagonal matrix with Toeplitz blocks. Such cases are physically well motivated and arise whenever the instrumental noise displays a piece-wise stationary behavior.
Our iterative algorithm is based on a conjugate gradient method with a parallel two-level preconditioner (2lvl-PCG) for which we construct its coarse space from a limited number of sparse vectors estimated solely from coefficients of the initial linear system.
Our prototypical application is the map-making problem in the Cosmic Microwave Background observations. We show experimentally that our parallel implementation of 2lvl-PCG outperforms by as much as a factor of 5 the standard one-level PCG in terms of both the convergence rate and the time to solution.
Chair/Author Details:
Costas Bekas (Chair) - IBM Research - Zurich
Laura Grigori - INRIA
Radek Stompor - Paris Diderot University
Mikolaj Szydlarski - INRIA
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A Parallel Two-Level Preconditioner for Cosmic Microwave Background Map-Making
SESSION: Numerical Algorithms
EVENT TYPE:
TIME: 1:30PM - 2:00PM
SESSION CHAIR: Costas Bekas
AUTHOR(S):Laura Grigori, Radek Stompor, Mikolaj Szydlarski
ROOM:355-EF
ABSTRACT:
In this work we study performance of two-level preconditioners in the context of iterative solvers of the generalized least square systems, where the weights are assumed to be described by a block-diagonal matrix with Toeplitz blocks. Such cases are physically well motivated and arise whenever the instrumental noise displays a piece-wise stationary behavior.
Our iterative algorithm is based on a conjugate gradient method with a parallel two-level preconditioner (2lvl-PCG) for which we construct its coarse space from a limited number of sparse vectors estimated solely from coefficients of the initial linear system.
Our prototypical application is the map-making problem in the Cosmic Microwave Background observations. We show experimentally that our parallel implementation of 2lvl-PCG outperforms by as much as a factor of 5 the standard one-level PCG in terms of both the convergence rate and the time to solution.
Chair/Author Details:
Costas Bekas (Chair) - IBM Research - Zurich
Laura Grigori - INRIA
Radek Stompor - Paris Diderot University
Mikolaj Szydlarski - INRIA
Click here to download .ics calendar file