January 1 ?

[Harti Brandt]

On Tue, 15 Jun 2004, Dik T. Winter wrote:

DTW> > mark wrote:
DTW> > > Jan 1st, 1 AD was Sunday or Saturday ?
DTW> > >
DTW> > > (question is related to C as I am writing a program (in C) to
DTW> > > calculate days/dates and need a starting point from where to start
DTW> > > counting.)
DTW>...
DTW> > > cal -j 1 0001
DTW> > January 1
DTW> > Sun Mon Tue Wed Thu Fri Sat
DTW> > 1
DTW> > 2 3 4 5 6 7 8
DTW>
DTW>I do not think this gives what you think it is giving; try cal -j 2 0001.
DTW>
DTW> > > cal 9 1752
DTW> > September 1752
DTW> > Su Mo Tu We Th Fr Sa
DTW> > 1 2 14 15 16
DTW>
DTW>Ah, yes... Now if cal recognised the country where you were, much more
DTW>interesting would have been 'cal 2 1712' in Sweden.

It gets even more interesting in Russia, because the orthodox church is
still using the old calendar (therefor Chrismas in Russia is on the 6th of
January), so 'cal' would need to recognize whether an orthodox priest is
typing or a normal human beeing

harti

 

[kal]

Jan 1st, 1 AD was Sunday or Saturday ?

It depends on what one implies by 1 AD. The concept of AD
was introduced only in c. the 6th century AD.

If you extend the current Gregorian system backwards then
Jan. 1, 1 AD would be MONDAY.

If you follow the practices of british colonies and extend
the julian calendar back for years 1752 and before then
Jan. 1, 1 AD would be SATURDAY.

If, on the other hand, you went back in time to the year
1 AD and asked about as to what day it was on Jan 1st then
Jan. 1, 1 AD would be SUNDAY.

This last case is due to the fact that 4 AD was not a leap
year in the julian calendar as observed by people of that
time (especially in Rome.) This, however, is not taken
into account by most routines that calculate Julian dates.

(question is related to C as I am writing a program (in C) to
calculate days/dates and need a starting point from where to start
counting.)

Today is as good a day as any.

 

[Richard Bos]

The interesting thing about it is that they would differ about the day to
which they point as January 1.

Of course.

And both would point to a day which actually
was not a January 1 at that time.

Not? AFAIK there has been no break in the Julian calendar from 45 BC
until 1582 AD, and while they didn't call it "January the first", I
think the day in question probably was called Kalendae Ianuariis, give
or take a grammar error.

Richard

 

[Ralf Damaschke]

Not? AFAIK there has been no break in the Julian calendar from
45 BC until 1582 AD, and while they didn't call it "January
the first", I think the day in question probably was called
Kalendae Ianuariis, give or take a grammar error.

Actually there were some anomalies.
In the first years the Romans used to insert a bisextile
every third year (based on their traditional counting scheme that
took each last leap year as the first year for the next period).
This was corrected in the Augustian era by omitting some leap
years until the accumulated deviation had been corrected.

Personally I am not quite sure of the consequences of the
renaming of a certain month and giving it 31 days in the same era.
Not to talk of the name "bisextile" which implies that the leap
day once was a second sixth day of some period (March, I believe).

 

[Dik T. Winter]

>
> Of course.
>
>
> Not? AFAIK there has been no break in the Julian calendar from 45 BC
> until 1582 AD,

Actually, there was a break. When Julius died the Romans started with
leap years every third year (*). The error was found and corrected by
Augustus by omitting a few leap years. Although the exact period is
not certain during which this happened, the most plausible is that
in 5 AD the normal pattern was started, with a firt leap year in 8 AD,
and so 4 AD was not a leap year.

 

[Dik T. Winter]

> Personally I am not quite sure of the consequences of the
> renaming of a certain month and giving it 31 days in the same era.

The latter appears not to be true.

> Not to talk of the name "bisextile" which implies that the leap
> day once was a second sixth day of some period (March, I believe).

No, Romans counted days backwards. So 1 March was the Kalendae of
March. The last day of February the Pridiae Kal. March, the day
before that III Ante Diem Kal. March, and counting further you
get VI A.D. Kal. March., which was the 24th of February. The
leap day was put between the 23rd and the 24th of February.

 

[Richard Bos]

Actually there were some anomalies.
In the first years the Romans used to insert a bisextile
every third year (based on their traditional counting scheme that
took each last leap year as the first year for the next period).

That was before 1 AD.

This was corrected in the Augustian era by omitting some leap
years until the accumulated deviation had been corrected.

All these are known; only one is after 1 AD.

Not to talk of the name "bisextile" which implies that the leap
day once was a second sixth day of some period (March, I believe).

Nope; the sixth before the Kalends of March, that is, the 23rd of
February.

Richard

 

[Irrwahn Grausewitz]

Actually, there was a break. When Julius died the Romans started with
leap years every third year (*).

[...]

Guys, may I suggest to mark the contributions to this thread OT,
since it's not really topical in c.l.c. Thank you very much.

BTW, I suggest to have a look at the calendar.faq:

http://www.tondering.dk/claus/calendar.html

It makes an interesting reading about date calculations and other
calendar related peculiarities.

Regards