sorry, I managed to find the solution at last (by reading the help but sometime is really difficult!)
Class "POSIXlt" is a named list of vectors representing yday 0–365: day of the year. another lesson learned bye -- View this message in context: http://r.789695.n4.nabble.com/julian-day-form-POSIXt-object-tp3855885p3859310.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.