Re: [boost] Re: reminder about Date/Time formal review

From: Victor A. Wagner, Jr. (vawjr_at_[hidden])
Date: 2002-04-26 01:13:06

Adding to the pedantry, my reference "Supplement to the American Ephemeris 
and Nautical Almanac" Britain and what is now the U.S.  (it wasn't the U.S. 
in 1751) adopted the Gregorian calendar on the same day, so July 4, 1751 
was the same day both in England _and_ the colonies.... by implication, 
July 4th 1752 was ALSO the same day.
At Wednesday 2002/04/24 07:37, you wrote:
>[deleted]
>Gotta
> > > > love this date stuff, no?)
> > >
> >
> > Wrong. Gregorian dates are not dependant on where your are in this way.
>What
> > is dependant is which colander was in use.
>
>July 4, 1751 in the US was a very different day then July 4, 1751 in
>England.  The reason, as you point out (and I thought was obvious from what
>I posted) is because the US didn't adopt the Gregorian system until Sept.
>14, 1752... or, more precisely, they adopted it on Sept. 2, 1752, which
>immediately became Sept. 14, 1752.  The point is, you can't project dates
>backwards with out knowing the location as well as the date.  Further, the
>"change over" date also effects this.  If the change over date used by the
>system were the American Sept. 14, 1752 this would mean the algorithm
>doesn't take into account things such as the missing day added at this time
>when dates are projected further back.
>
> > Gregorian (Sept 14, 1752)-1 = Gregorian(Sept 13, 1752) = Julian(Sept 2,
> > 1752)
>
>The above isn't accurate.  Gregorian (Sept. 14, 1752) - 1 = Gregorian (Sept.
>12, 1752)

Ummm, I think you mean Gregorian(Sept. 13, 1752) .... not 12

>if you were in one of the regions that adopted the Gregorian
>calendar in 1582, or Julian (Sept. 2, 1742) if you were in America or one of
>the other locations that was still using the Julian calendar.  The problem
>is that the Gregorian calendar has not been a stable system, with 10 days
>being added to the Julian system in 1582 and 11 days being added in 1752
>when America switched over.

There weren't 11 days "added" to the Gregorian calendar in 1752, the 
Gregorian calendar and the Julian calendar were the 11 days apart (as 
opposed to 10 days apart in Oct 1582 when pope Gregory decreed the original 
change).  I have no idea what you mean by "not been a stable system"

>Bill Kempf
>_______________________________________________
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Victor A. Wagner Jr.      http://rudbek.com
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