On Sep 27, 2005, at 6:58, Randy Kramer wrote:

> On Tuesday 27 September 2005 04:51 am, Robert Klemme wrote:
>> No, I mean because of the underlying model (our calendar).  Months 
>> have
>> different lengths.  Same for years and quarters.
>
> Two thoughts, which I don't know whether will help or hurt (may be 
> useful
> approximations?):
>
>
>    * Depending on the level of precision I wanted, I might calculate an
> interval in weeks, then consider 4 1/3 weeks ~= 1 month, 13 weeks ~= 1
> quarter, and 52 weeks = 1 year.  If I wanted to express some arbitrary 
> number
> of weeks in months, (e.g., 62, I'd divide by 4.34 and round off to the
> nearest integer and call it that number of months.
>
> Nope, I take that back.  I'd more likely just express the difference 
> between
> say, Jan 3rd and Dec 15 as the difference in months then the 
> difference in
> days, i.e., 11 months, 12 days.  (and I'd approximate that as either 
> 11, 11
> 1/2, or 11 months, 2 weeks).

[text deleted]

> Do others see the need for other approaches?


There is no "answer" to this problem because the correct usage is 
tremendously context sensitive.

There are 58 shopping days until Christmas.

The convention is in 8 weeks. (58 days = 8.2 weeks)

Your work on the Monster House must be complete in 2 days, 12 hours, 14 
minutes, and 34.5 seconds.

The Date class (if I recall correctly) uses Days and fractions of Days 
for the internal representation, and lets you access a variety of 
interval measures. Which ones you use will depend very much on what 
kind of events you're measuring the distance between.