Hello Wang matrix bb is symmetric positive semidefinite, so algebraically the eigenvalues are nonnegative.
I would use bb <- crossprod(b) to calculate bb (faster and possibly more accurate) Look at eigen(bb,TRUE,TRUE)$values (see ?eigen for the meaning of the arguments) to see how many very small eigenvalues you have. The number of zero eigenvalues is equal to the number of linear relations in the columns of b. HTH rksh On 12 Dec 2007, at 10:59, Wang Chengbin wrote: > I got the following error: > > a = read.csv("mat.csv") > b = as.matrix(a) > tb = t(b) > bb = tb %*% b > dim(bb) > ibb = solve(bb) > bb %*% ibb > >> ibb = solve(bb) > Error in solve.default(bb) : > system is computationally singular: reciprocal condition number = > 1.77573e-19 >> > Are there any ways to find more information about why it is singular? > > Thanks. > ______________________________________________ > 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. -- Robin Hankin Uncertainty Analyst and Neutral Theorist, National Oceanography Centre, Southampton European Way, Southampton SO14 3ZH, UK tel 023-8059-7743 ______________________________________________ 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.