On Fri, Oct 26, 2012 at 12:14 PM, langvince <la...@purdue.edu> wrote:
> Whatever I do, however I subset it I get the "system is computationally > singular: reciprocal condition number" error. > I know what it means and I know what should be the problem, but there is no > way this is a singular matrix. > > I have uploaded the input file to my ftp: > http://mkk.szie.hu/dep/talt/lv/CentInpDuplNoHeader.txt > It is a tab delimited txt file with no headers. It's a singular matrix. The data matrix has rank 300 according to either qr() or svd(). The 301st singular value is about ten orders of magnitude smaller than the 300th one. The problem is the rounding of the values -- if you take 372 vectors in 380-dimensional space they should be linearly independent, but if you force them to lie on a relatively coarse grid there are quite likely to be linear dependencies. When I add random noise in the fourth decimal place, the matrix stops being singular. -thomas -thomas -- Thomas Lumley Professor of Biostatistics University of Auckland ______________________________________________ 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.
