Here is some python code I adapted from this stackoverflow post to get the first day of a week specificed by a week number. This method includes leap year and summer time differences.
import time def weeknum(num,year): instr = str(year)+" "+str(num-1)+" 1" print time.asctime(time.strptime(instr,'%Y %W %w'))
Here is me exectuting the code in Python’s IDLE shell:
See that the first week of 2009 actually started in 2008, but by the end of that week we are in 2009.