ISO-8601 Week Number from Date()

[Michael REMY]

another way :

public function WeekNumber(adate:Date):int{
				//
				// 1 - CALC JULIAN DATE NUMBER (note: nothing to do with the Julian calendar)
				//
				var wfullyear:int = adate.getFullYear();
				var wmonth:int = adate.getMonth() + 1;
				var wdate:int = adate.getDate();
				//
				var wa:int = Math.floor((14 - wmonth) / 12);
				var wy:int = wfullyear + 4800 - wa;
				var wm:int = wmonth + 12 * wa - 3;
				//
				// wJDN is the Julian Day Number
				//
				var wJDN:int = wdate + Math.floor(((153 * wm) + 2) / 5) + wy * 365
				                     + Math.floor(wy / 4)
				                     - Math.floor(wy / 100)
				                     + Math.floor(wy / 400) - 32045;
				//
				// 2 - CALC WEEK NB
				//
				var d4:int = (((wJDN + 31741 - (wJDN % 7)) % 146097) % 36524) % 1461;
				var L:int = Math.floor(d4 / 1460);
				var d1:int = ((d4 - L) % 365) + L;
				var wweekNb:int = Math.floor(d1 / 7) + 1;
				return wweekNb;
			};

[squadjot]

another way :

public function WeekNumber(adate:Date):int{
				//
				// 1 - CALC JULIAN DATE NUMBER (note: nothing to do with the Julian calendar)
				//
				var wfullyear:int = adate.getFullYear();
				var wmonth:int = adate.getMonth() + 1;
				var wdate:int = adate.getDate();
				//
				var wa:int = Math.floor((14 - wmonth) / 12);
				var wy:int = wfullyear + 4800 - wa;
				var wm:int = wmonth + 12 * wa - 3;
				//
				// wJDN is the Julian Day Number
				//
				var wJDN:int = wdate + Math.floor(((153 * wm) + 2) / 5) + wy * 365
				                     + Math.floor(wy / 4)
				                     - Math.floor(wy / 100)
				                     + Math.floor(wy / 400) - 32045;
				//
				// 2 - CALC WEEK NB
				//
				var d4:int = (((wJDN + 31741 - (wJDN % 7)) % 146097) % 36524) % 1461;
				var L:int = Math.floor(d4 / 1460);
				var d1:int = ((d4 - L) % 365) + L;
				var wweekNb:int = Math.floor(d1 / 7) + 1;
				return wweekNb;
			};

very useful! thanks...