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PRODID:-//Microsoft Corporation//Outlook MIMEDIR//EN
VERSION:1.0
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DTSTART:20121115T203000Z
DTEND:20121115T210000Z
LOCATION:355-EF
DESCRIPTION;ENCODING=QUOTED-PRINTABLE: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. =0AOur 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.=0A=0AOur 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.
SUMMARY:A Parallel Two-Level Preconditioner for Cosmic Microwave Background Map-Making
PRIORITY:3
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