which day of the week

[SpriggsySpriggs]

From Julian to Gregorian, yes.

[SierraKen]

Chat GPT says it was a Saturday on Jan. 1, 1 A.D., but only if you go by the Julian Calendar and count back. If you go back in time in a time machine, they didn't have our weekdays until 321 A.D. Before that there were other weekdays, like the 8 day Roman one, or 7 day ones by other groups (Christians, Jewish, Babylonians). But it wasn't universally made until 321 A.D. by Constantine.

[Pete]

Hope to clear things up a bit with this Columbus Day demo, but short answer... When was Columbus Day in 1492? No day... It hadn't been invented until 1971.

Anyway, the demo shows all leap years in yellow, non in white. It shows the difference in calendar days for each year, 365 or 366 (except the first year, 1492). What you will notice that unless it is a leap year the progression is the next day each year. On a leap year it skips to the day after next. The pattern proves if the algorithm used is correct.

Code: (Select All)

' Columbus Day "Day of the Week" from 1492 on...

' Using Gregorian calendar algorithm, which was not available (invented) until 1582.

Width 80, 43

_ScreenMove 0, 0

map$ = "Sunday    Monday    Tuesday  Wednesday Thursday  Friday    Saturday"

year = 1492

month = 10

Rem January = 0, February = 31,March = 59, April = 90, May = 120, June = 151, July = 181, August = 212,,September = 243, October = 273, November = 304 and December = 334

oct = 273

day = 12

Do

    leapyear = 0

    ans = (365 * year) + year \ 4 - year \ 100 + year \ 400 - 365

    If year Mod 4 = 0 And year Mod 100 Or year Mod 4 = 0 And year Mod 100 = 0 And year Mod 400 = 0 Then leapyear = 1

    If leapyear And month < 3 Then ans = ans - 1

    ans = ans + oct + day

    dow = ans Mod 7

    If leapyear Then Color 14 Else Color 7

    Print year, ans, ans - oldans, "Oct 12,"; year; "falls on a " + Mid$(map$, 10 * dow + 1, 10)

    year = year + 1

    oldans = ans

    Sleep

Loop

Pete

[bplus]

Chat GPT says it was a Saturday on Jan. 1, 1 A.D., but only if you go by the Julian Calendar and count back. If you go back in time in a time machine, they didn't have our weekdays until 321 A.D. Before that there were other weekdays, like the 8 day Roman one, or 7 day ones by other groups (Christians, Jewish, Babylonians). But it wasn't universally made until 321 A.D. by Constantine.

Actually I was going for the very first day of AD in the year 0.

Remember you need to go a whole year, 365+ days before year 1 starts.

But sure, at that time nobody knew it was AD yet

[macalwen]

October 4, 1582 week 4, before this date the Julian calendar was used, with a leap year every 4 years, and working backwards from this, then January 1, 1 AD was week 6, October 5 to 14, 1582 was canceled, so October 15, 1582 was week 5, and from this date onwards the Gregorian calendar was used, with a slightly different calculation of leap years. To take all of this into account, it can only be calculated separately.

[Pete]

October 4, 1582 week 4, before this date the Julian calendar was used, with a leap year every 4 years, and working backwards from this, then January 1, 1 AD was week 6, October 5 to 14, 1582 was canceled, so October 15, 1582 was week 5, and from this date onwards the Gregorian calendar was used, with a slightly different calculation of leap years. To take all of this into account, it can only be calculated separately.

I put a +2 on your initial post for addressing the calendar change up. It made me decide to stop my routine from going back prior to 1583. I use it for appointments, so unless I make a time machine... Which if I ever do you'd think I know about it by now, going back in times past the first day of use was not something I was concerned about. At least now it can't be misused in that regard,

Pete

[Stuart]

I've been following this thread for a while now and wanted to share this info for anyone that might be as confused as I was at this point...
-->

"The year 1752 is a leap year, with 355 days in total (The calendar changed from the Julian to the Gregorian calendar this year, and a number of days were dropped during this process)"

(The day/date before Thursday, 09/14/1752 was Wednesday, 09/02/1752.)

September 1752
Su Mo Tu We Th Fr Sa
...........1 ..2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

The above info can be found here :
https://www.timeanddate.com/calendar/?ye...&country=1

More info about Calendar Reform can be found here :
https://en.wikipedia.org/wiki/Calendar_(...)_Act_1750

==========================================================================
I wrote a program named TIMECALC.BAS many years ago (using GW-BASIC) that is based on this page :
https://www.timeanddate.com/date/timeduration.html
It will display time and date calculations as well as the day of week for any particular date.
I'll post that in a different thread and leave a link to it here if anyone is interested.

Julian dates : 01-01-0001 to 09-02-1752
Gregorian dates : 09-14-1752 to 02-28-4000
Probable dates : 03-01-4000 to 12-31-9999

(The PROBABLE [proposed] CALENDAR [unofficial] does not consider the year 4000 or the year 8000 to be a leap year.)
==========================================================================

@bplus

MORE INFO ABOUT WHY THERE IS NO YEAR 0 (zero) CAN BE FOUND HERE :
https://www.historyskills.com/classroom/...ce-meaing/

This shorter page has this quote :

"Unlike BC, AD years move forward from year 1. There is no year 0—the timeline goes directly from 1 BC to AD 1."

This longer page has more detailed info about why there is no year 0 :
https://www.calendarr.com/united-states/...fferences/

[bplus]

Re: Quote about skipping the year 0

Obviously not the work of mathematicians, must of been one of those nutty political things
(I should probably read the link before making these statements but wheres the fun in that? OK I am on record for my guess as to what happened to the year 0.)

OK I read it and still don't understand, did it take a whole year for Christ to be born? We go from 1 BC down to 6 months BC 5,4,3,2,1 days BC then suddenly it's 1 AD?

Here's another theory: 0 wasn't invented yet as a place holder, just like negative numbers were not real. Very primative days back then.

[SMcNeill]

This calendar era takes as its epoch the traditionally reckoned year of the conception or birth of Jesus. Years AD are counted forward since that epoch and years BC are counted backward from the epoch. There is no year zero in this scheme; thus the year AD 1 immediately follows the year 1 BC. This dating system was devised in 525 by Dionysius Exiguus but was not widely used until the 9th century.

It might help if you realize that the term anno Domini is Medieval Latin and means "in the year of the Lord".

So 1AD is basically the first "year of the Lord". 1BC is 1 "year before Christ".

(Which oddly enough is not accurate now, as modern scholars think that Christ was born back in 5 BC...)

[Pete]

All I care about is who was Miss July back then. If anybody says it was Wilma Flintstone, you're in big Betty Rubble trouble!

Pete

- I'm just counting the days 'til the idiot bus, and its fares, leaves the White House.