PEAR::Calendar: Can you build a week with only the year and the week number

Hi all, From the documentation I can't see whether it's possible to build a specific week just from the year and the week number. Ideally I'd like to build the week like this $Week = new Calendar_Week($year, $weeknumber, 'n_in_year'); but that's not possible (yet) so I'm wondering whether there is an other way to achieve the same result without having to iterate through the whole year. Thanks a lot Peter