Re: Zeller's Algorithm

[Paul A Storm <paul.a.storm@lmco.com>]

Thomas Wolf wrote:

I downloaded your code and ran the test routine, np.  I'll check out the
contents.  I had already
decided to use a Julian conversion with a mod 7 as a basis for "Plan
B".  Thanks for your
reply.

I am still confused as to why the Zeller algorithm wouldn't work.  Since
the algorithm has been
around since 1875 I figure it has proven out.  Although I am still
cogitating on whether it
takes into account for centennial non-leap years(1800,1900, etc.) and
quatra-centennial leap years(i.e. 2000).
It bugs me when I can't figure out the reason for some code not
working.  Know what I mean?

Did you try to compile the program from the link I gave and did you have
any problems like I had?

> 
> paul.a.storm@lmco.com wrote:
> > Help!
> >
> > I am trying to find a Ada implementation of Zeller's algorithm that
> > works!  I have found several on the web
> > but none of them have worked right.
> >
> > For example I tried this one from
> > http://www.adapower.com/alg/zeller.html  Inputting June 19 2002 returns
> > Wednesday, correct.  Inputting June 19 1999 produces Sunday, incorrect.
> > That's a Saturday. Inputting
> > February 3, 2002 produces Friday, incorrect.  That's a Sunday.  What
> > gives?
> >
> > I have had similar weird results using other similar Ada Zeller versions
> > I've found on the web.
> 
> You might try the Util.Calendar packages from my Util subsystem,
> available at the URL
> 
> http://home.tiscalinet.ch/t_wolf/tw/ada95/util/
> 
> Util.Calendars.Universal.Day_Of_Week produces the correct results.
> See the test driver in ./test/calendar_test.adb for some examples.
> 
> The Util subsystem is published under the GMGPL.
> 
> --
> -----------------------------------------------------------------
> Thomas Wolf                          e-mail: t_wolf@angelfire.com

-- 
My perspicacity is only eclipsed by my pertinacity