Given a date, get the next or previous Monday, or Tuesday etc from the given date. This is useful when working with ical recurring dates.  If the date given is already that day of week, it is returned as the result. For example to get the following Every 20th Monday of the year, forever: DTSTART;TZID=US-Eastern:19970519T090000 [...]

Here  is a simple first of several notes on useful date functions.  This function accepts  a year  (YYYY) and a Day in the year (1 to 366), and returns a DateTime Object. /* Year if format YYYY, Day in year 1 to 366 */ function dayofyear2date( $year, $DayInYear ) { $d = new DateTime($year.’-01-01′); date_modify($d, [...]