Getting Previous Period Date

Question

Hello - I'm wondering if anyone can help.
Im currently developing a tool which filters and aggregates some data. I have the user to be able to select a period for example - 01/01/2010 to 07/10/2010.
Then, I want to compare the selected data with the same period of the previous.
I understand that I think I get do this with the .getTime function but Im at a loose end as to how to achieve this. Another example is if the user selects 2 years, e.g. 01/01/2010 - 01/01/2008 the comparison period would be 01/01/2006 - 01/01/2008
Please help!
Thanks
Craig
public function filterAll(evt:Event):void
                var tmpDate:Date = selectedFrom.selectedDate
                var tmpDate2:Date = selectedTo.selectedDate
                tmpDate.time = tmpDate.getTime();
                tmpDate2.time = tmpDate2.getTime(); // this needs to be the previous period
                trace (tmpDate)
                trace (tmpDate2) // trace previous period

Answer 1

Think I've done it! Here is the function for anyone that is interested!
public function getPreviousPeriod(From:Date,To:Date, fromOrTo:String):Date
                var diffNum:Number = From.getTime() - To.getTime();
                var tmpDate:Date = new Date
                var tmpDate2:Date = new Date
                tmpDate.time = From.getTime();
                tmpDate2.time = To.getTime();
                tmpDate.time = tmpDate.getTime() + diffNum
                tmpDate2.time = tmpDate2.getTime() + diffNum
                if (fromOrTo == "From")
                    trace ("FROM")
                    return tmpDate;
                else
                    trace ("TO")
                    return tmpDate2;