Duncan, Berwin, Martin, Thanks for your thoughtful explanations, which make perfect sense.
May I simply suggest that the non-identity between last(cumsum) and sum might be worth mentioning in the cumsum doc page? -s ______________________________________________ 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.