>>>>> "AR" == Alex Roy <alexroy2...@gmail.com> >>>>> on Tue, 4 Aug 2009 09:56:42 +0200 writes:
AR> Dear all, Rank of a matrix depends on which factors? AR> Only on rows or coumns? or both ? If there is a AR> collinearlity in the variables ( columns ) does it AR> effects the rank? This has nothing to do with R, even though you provide R code here:. Please learn about this, maybe from Wikipedia: http://en.wikipedia.org/wiki/Rank_%28linear_algebra%29 >> X<-matrix((rnorm(10000)),50) dim(X) AR> [1] 50 200 >> qr(X)$rank AR> [1] 50 >> X[,2]<-X[,30] qr(X)$rank AR> [1] 50 >> X[10,]<-X[7,] qr(X)$rank AR> [1] 49 Note that the rank of a matrix is well defined in theoretical linear algebra, but in practice is quite a bit more complicated. For this reason, and to bring this back to a topic more fit to R-help : The package 'Matrix' (typically part of R, since R 2.9.0), has a function rankMatrix() whose options {and implementation; just type 'rankMatrix' !} show you a bit about the problematics. Regards, Martin Maechler, ETH Zurich ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.