GetRoshHashanah – Retrieving the date that Rosh Hashanah begins in the requested year

' Returns the date that Rosh Hashanah begins for the requested year.' It is important to note that Rosh Hashanah is based on the Lunar cycle so the ' Holiday actually begins at sunset of the day before the date returned by this ' function.' Note: Many dates in the Jewish calendar are dependent on the date of Rosh ' Hashanah just as Good Friday, Lent, and other dates are dependent on Easter. Function GetRoshHashanah(ByVal iYear As Integer) As Date    Dim dDate As Single, iDate As Integer, iDayOfWeek As Integer    Dim JY, JtoG, iMonth As Integer    ' Conversion factors    Const F1 As Single = 765433 / 492480    Const F2 As Single = 23269 / 25920    Const F3 As Single = 765433 / 492480    JY = (12 * ((iYear Mod 19) + 1)) Mod 19    ' Correct from Julian date to Gregorian date    JtoG = iYear  100 - iYear  400 - 2    dDate = JtoG + F1 * JY + (iYear Mod 4) / 4 - (313 * CLng(iYear) + 89081) / _        98496    ' Get the integer portion of the date    iDate = CInt(Math.Floor(dDate))    ' Get the fractional portion of the date    dDate = dDate - iDate    If iDate > 30 Then        iDate = iDate - 30        iMonth = 10    ElseIf iDate < 1 Then        iDate = iDate + 31        iMonth = 8    Else        iMonth = 9    End If    iDayOfWeek = (New Date(iYear, iMonth, iDate).DayOfWeek) + 1    ' Postponement Rules    ' If day of week is Sunday, Wednesday, or Friday    If iDayOfWeek = 1 OrElse iDayOfWeek = 4 OrElse iDayOfWeek = 6 Then        iDate = iDate + 1        ' If day is Monday    ElseIf iDayOfWeek = 2 AndAlso dDate > F1 AndAlso JY > 11 Then        iDate = iDate + 1        ' If day is Tuesday we may need to add two days    ElseIf iDayOfWeek = 3 AndAlso dDate >= F2 AndAlso JY > 6 Then        iDate = iDate + 2    End If    If iDate > 30 Then        iDate = iDate - 30        iMonth = 10    ElseIf iDate < 1 Then        iDate = iDate + 31        iMonth = 8    Else        iMonth = 9    End If    Return New Date(iYear, iMonth, iDate)End Function

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