For some unknown reason I stopped receiving any messages from the R- help mailing list. See if this test gets through.
Thanks, Gang ______________________________________________ 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.