logical variable. If TRUE (default) the date is returned as data frame (like data in extractyears), otherwise it is returned as character or POSIXct.
decimal
logical variable. If FALSE (default) k is integer and starts from 1, otherwise is consider as the decimal julian day since origin (deprecated)
character
logical variable. It is used if data.frame is FALSE, if it is FALSE, the date is returned as POSIXct, otherwise it is a character in the following form: YYYY-MM-DD
Value
the date(s) corresponding to k under different formats