>>Hi everybody,
>>
>>Given 52 weeks in a year and week definition (from Sat through Friday) I need to calculate Week's first day, week's last day and some other dates for the given year for each week. What would be a formula here?
>>
>>Thanks a lot in advance.
>

This may be closer to actual function you want:

procedure getFirstDateofWeek
lparameters lnYear, lnWeek
    lnFirstDOW = 7   && Saturday

    lnFirstDate = date(lnYear, 1, 1) + (lnFirstDOW - dow(date(lnYear, 1, 1)))
    return lnFirstDate + (lnWeek - 1)*7
endproc