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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao zbMATH Openarrow_drop_down
image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
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SIAM Journal on Scientific and Statistical Computing
Article . 1984 . Peer-reviewed
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Condition Estimates

Condition estimates
Authors: Hager, William W.;

Condition Estimates

Abstract

Cline/Moler/Stewart/Wilkinson gave a strategy for estimating the condition number \(\mu:=\| A\|_ 1\| A^{-1}\|\) of an \(n\times n\)-matrix A, which is incorporated in LINPACK. It needs the solution of two systems with A and \(A^ T\), but underestimates \(\mu\) by a factor of 0.55 in average, and this factor is getting worse with growing n. The author develops a new idea by considering the relative maxima of the convex function \(f(x):=\| Bx\|_ 1\). He achieves an average factor of 0.97, which obviously is not depending on n and needs 4.2 system solutions with A and \(A^ T\) in average. By splitting this method in cycles in certain subspaces it is possible to reach factors 0.991 and 0.997 by doubling and trebling the effort resp. The worst estimate for 200 random matrices of different orders are 0.32, 0.44 and 0.7 for one, two and three cycles resp.

Keywords

Numerical computation of matrix norms, conditioning, scaling, estimating the condition number

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
147
Top 10%
Top 1%
Average
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