Gustav Brock
gustav at cactus.dk
Fri Aug 1 14:29:02 CDT 2003
Hi Bobby
> This function can be made even more generic by passing in the month, day,
> year, and day fraction (or the day as a fraction 12/4/2003 6:00AM would be
> 12, 4.25, 2003). This way, the function can handle years BC.
> Just in case anyone cared. :-)
Well, could be interesting ... who knows, but it still fails an
example like this:
? (Greg2jd("03/01/1992") - Greg2jd("03/01/1987")) / 365.25
4,99931553730322
like any other method relying on dividing by 365,25. This method is
what we call a "shoemaker method" as it is a method working in "most
cases" but not all.
This is not to pick on you - because it is still published many places
- but for the records, so no list member should be tempted to use a
quick and dirty suggestion for serious use.
/gustav
> Public Function Greg2JD(ByVal strDate As String) As Double
> Dim A As Long
> Dim B As Long
> Dim MM As Long
> Dim YY As Long
> Dim DD As Single
> MM = Month(strDate)
> YY = Year(strDate)
> DD = Day(strDate)
> 'note, you could pass the time of day in as a fraction of a day.
> 'if you do so, simply add the fraction of the day to DD
> 'As is, this code assumes 0 hour, i.e. if it is the 4th,
> 'then it assumed to be the 4th at 12:00:00 AM
> 'DD = DD + sDayFrac 'sDayFrac is the variable holding fraction of day
> If MM < 3 Then
> YY = YY - 1
> MM = MM + 12
> End If
> A = YY \ 100 'integer math
> B = 2 - A + A \ 4 'integer math
> Greg2JD = Int(365.25 * (YY + 4716)) + Int(30.6001 * (MM + 1)) + DD + B -
> 1524.5
> End Function
> To work out our example, I called it with:
> Debug.Print (Greg2JD("02/18/2002") - Greg2JD("02/29/1988")) / 365.25