[AccessD] Age calculation function

I tested several expressions years ago and came up with only one -- based
strictly on date arithmetic -- that consistently worked, in any century,
with any date, at any time. If you can't find that works for you, I'll be
glad to dig it up.

Anything that's based on increments or components is bound to fail sooner or
later -- but it could fail only on the Tuesday following the year of the
Chinese Rat, after the first full moon and only if it rained -- but
eventually, they all seem to fail.

Susan H.


> 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
>
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