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From: "Yi Cao" <y.cao@cranfield.ac.uk>
Newsgroups: comp.soft-sys.matlab
Subject: Re: An interesting numerical problem
Date: Thu, 22 Oct 2009 19:18:21 +0000 (UTC)
Organization: Cranfield University
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"Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <hbq6hb$5me$1@fred.mathworks.com>...
> 
> cond(P19*P19') is larger than 10^20. Eigen-space are highly parallel. The fact that P19 contains integer does not matter IMO because DET calculation using LU factorization.
> 

For L*U = P*P', theoretically, L should be P and U should be P' because P is low triangular and P' is upper triangular.  Clearly, LU factorization in Matlab is not so smart.

Yi