[Aimmath-developers] AutoConf*.mpl,Date.mpl,ManualConf.dist changes

[Greg G. <gr...@ma...>]

Dear developers,

Well 4th April came around and I got burnt again ... I was under the
mistaken apprehension that the Summer Time bugs had been fixed. 
(I misread the meaning of the statement in this regard in 
ManualConfig.dist.) I suppose newDate.mpl was supposed to fix it,
but it doesn't seem to be finished.

I note that you guys in the Northern Hemisphere will be burnt at the
other end because the date give for 2004 for the finish of Summer Time
is 26th October which is a Tuesday.

It's my belief that just doing a cvs update and doing

  read "AutoConf.mpl";

in maple, in AIM's .../WEB-INF/maple directory is all that's required
to fix things.

Anyway, I made changes to:

  AutoConf.mpl, AutoConfWin.mpl, Date.mpl and ManualConf.dist

I'm not sure if there need to be compensatory changes in AutoConfWin.mws.
Perhaps someone could check that.

Anyway, the main change is the introduction of the variable
`Date/SummerTimeSpec` with which one can set the Summer Time specification
for one's locale without being defaulted to a possibly erroneous setting
for the Northern Hemisphere. 

New functions added in Date.mpl are:
  `Date/DaysSince1Jan2000`, `Date/DayOfNthSundayOfMonth`, `Date/Test`

Also, `Date/SummerTime` is now a function (rather than a table), that
returns a list consisting of two month, day pairs which are the beginning
and end dates of Summer Time for the locale, determined from
`Date/SummerTimeSpec`.

Finally, `Date/IsSummer` now takes account of whether there is no Summer
Time, or whether the locale is in the Northern or Southern Hemisphere.

To explain how it all fits together, let's consider the default
`Date/SummerTimeSpec` which is [[4, 1], [10, 5]] which specifies
that Summer Time goes from April's 1st Sunday, until October's
5th or last Sunday. Given a year, month and a Sunday ordinal,
`Date/DayOfNthSundayOfMonth` returns a list specifying the day of the 
month on which the Sunday occurs, e.g. 

  `Date/DayOfNthSundayOfMonth`(2004, 10, 5)

returns [10, 31], i.e. the 5th(= last) Sunday of October occurs on the
31st of that month. Someone might like to check that Summer Time in
the Northern Hemisphere does indeed finish on the 31st October this year.
In any case, I feel confident that it doesn't finish on 26th October.

A special case is the case we have here in Western Australia (no Summer
Time at all), and this is specified by setting `Date/SummerTimeSpec`
to [[0, 0], [0, 0]]. 

The possible values of `Date/SummerTimeSpec` that I know of (including
various parts of Australia) are all listed in ManualConfig.dist.
I'm quite probably the only Southern Hemisphere user currently, but
conceivably this may change.

  Regards,
  Greg