From: Jeremy Hinegardner <jeremy@...>
Date: 2004-03-19T00:52:40+09:00
Subject: Re: Thinking about a date-matching algorithm...

>>>>> "Hal" == Hal Fulton <hal9000@hypermetrics.com> writes:

Hal> I did a little swapping of ideas with dblack on this. Now I'm
Hal> opening discussion to anyone interested.

Hal> I'm writing a little to-do manager (chiefly for my own use).

Hal> I want to allow recurring tasks. Some of these will be simple, like
Hal> "Every Monday." Others will be more complex, like "Every 2nd and
Hal> 4th Friday." Some might not even be based on weeks or months at
Hal> all, but might be like: "Every ten days, no matter what."

Hal> There'd also be an option to give advance warning (N days) on each
Hal> event.

Hal> So the question becomes: Given a date (typically "today") and a
Hal> list of recurring tasks, how do I determine which ones need to be
Hal> displayed?

You might check out the remind application and see what algorithms it 
uses.  Its been around a while and can do some fairly complex recurring 
tasks.  
 
       http://www.roaringpenguin.com/products/remind/index.php 
 
Also "Calendrical Calculations" by Nachum Dershowitz and Edward 
M. Reingold is a great general purpose calendaring book. 
 
enjoy, 
 
-jeremy 

-- 
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 Jeremy Hinegardner                              jeremy@hinegardner.org