Talk:Gregorian calendar

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Difference between Julian and Gregorian dates[edit]

In the third century the difference was zero. Thus H-(H/4)-2=2-[2/4]-2=2-0-2=0. In these equations the square brackets [ ... ] denote integer division.

In the second century the difference is -1. Thus 1-[1/4]-2=1-0-2=-1.

In the first century the difference is -2. Thus 0-[0/4]-2=0-0-2=-2.

In the first century BC the difference is -2. Thus -1-[-1/4]-2=-1-(-1)-2=-2.

In the second century BC the difference is -3. Thus -2-[-2/4]-2=-2-(-1)-2=-3.

In the third century BC the difference is -4. Thus -3-[-3/4]-2=-3-(-1)-2=-4.

In the fourth century BC the difference is -5. Thus -4-[-4/4]-2=-4-(-1)-2=-5.

In the fifth century BC the difference is -5. Thus -5-[-5/4]-2=-5-(-2)-2=-5.

So the section was correct as written. You should put it back the way it was. (talk) 13:10, 10 May 2015 (UTC)

It is perhaps less confusing if the mathematically equivalent relation D = floor(y/100) - floor(y/400) - 2 is used. Here y denotes the year and 'floor' denotes the floor or entier function. AstroLynx (talk) 13:50, 10 May 2015 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── The floor function gives a different result than truncation for negative numbers. I think it's better to use a relationship from a reliable source, so if the article is vandalized, an editor who does not want to rederive and retest the relationship can just restore the relationship from the cited source.

Let us postpone consideration of edge cases, after we agree on a correct formula for mid-century.

In the following table AYN means astronomical year numbering. The years assigned to centuries is common in offical sources but the Oxford English Dictionary said 2000 was the first year of the 3rd millenium. In ranges, the word "to" is inclusive, that is, "1 to 100" means 1 January AD 1 through 31 December AD 100. "Computed Secular Difference" is using the formula in the article [D = H - (H/4) -2, truncating division] which agrees with Blackburn and Holford-Strevens, using the value of H for mid-century to avoid edge cases (AD 250, AD 150, ... -550 BC).

The "Calendrica Secular Difference" was computed using the Calendrica LISP program provided by Cambridge University Press for use with Dershowitz and Reingold's book. Calendrica was used to convert Gregorian June 15 of the mid-century year to Julian and the difference is tabulated.

Century name 3rd AD 2nd AD 1st AD 1st BC 2nd BC 3rd BC 4th BC 5th BC 6th BC
Years included (AYN) 201 to 300 101 to 200 1 to 100 -99 to 0 -100 to -199 -200 to -299 -300 to -399 -400 to -499 -500 to -599
Computed Secular Difference 0 -1 -2 -2 -3 -4 -5 -5 -6
Calendrica Secular Difference 0 -1 -2 -2 -3 -4 -5 -5 -6

Jc3s5h (talk) 15:05, 10 May 2015 (UTC)

Gregorian calendar#Months of the year - numerical method text uses unreliable source[edit]

See User_talk:JoeSperrazza#Gregorian_calendar.23Months_of_the_year_-_numerical_method_text_uses_unreliable_source. JoeSperrazza (talk) 04:22, 11 August 2015 (UTC)

P.S. A formatting error occurred whenever I pasted the comment made at User_talk:JoeSperrazza#Gregorian_calendar.23Months_of_the_year_-_numerical_method_text_uses_unreliable_source into this section of the article talk page. Thus, I posted it to my talk page. Discussion would be better here, however. JoeSperrazza (talk) 14:19, 11 August 2015 (UTC)

North Korean Calendar?[edit]

In the infobox there is no reference to the North Korean Calendar[1]. PLEASE ADD!

North Korea Calendar?[edit]

There is no reference to the North Korean Calendar[2] in the infobox. (talk) 10:13, 18 August 2015 (UTC)

It's under Juche calendar. If you have any other issues with the infobox go take it up on the box's talk page. Arcorann (talk) 06:45, 21 August 2015 (UTC)


  1. ^  Missing or empty |title= (help)
  2. ^ North Korean Calendar. Wikipedia  Missing or empty |title= (help)

Julian calendar[edit]

Julian calendar was a kind of ancient Occidental solar calender is that right? SA 13 Bro (talk) 22:46, 14 September 2015 (UTC)

Sort of. It was ordered by Julius Caesar, so it is western and ancient. And it is solar. But it was still in use in Greece as an official government calendar until 1923, and it is still used by some branches of the Orthodox Church. So it is also modern. Jc3s5h (talk) 23:07, 14 September 2015 (UTC)
Jc3s5h That was the GREAT men! The ancient kind of solar calender is still using at the modern time... SA 13 Bro (talk) 23:22, 14 September 2015 (UTC)

Semi-protected edit request on 31 December 2015[edit]

the text says that Eatern Orthodox churches are using the old calendar but Romania and Bulgaria are orthodox but use the gregorian calendar (talk) 18:04, 31 December 2015 (UTC)

Red question icon with gradient background.svg Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format. Datbubblegumdoe[talkcontribs] 02:49, 7 January 2016 (UTC)

England and Jan 1[edit]

The article is unclear or misleading about England's shift to "New Style Julian". It states that the change to January 1st was made (officially) in 1752, but that January 1st was regarded informally as New Year's Day, and gives an example from Samuel Pepys. So far, so good. It is left open just how far people thought of the year as starting in January, but the implication is that the January start was just an informal concept.

However, year-start on January 1st was in fact in formal (if not "official") written and printed usage in England before 1752. For example, in the London Newspaper The General Advertiser, issue number 4114 was dated Thursday December 31, 1747, and issue number 4115 was dated Friday January 1, 1748.

How general, and when, was public adoption of "New Style Julian?". Were the newspapers really living in different years from officialdom for nearly three months of every year? Could a knowledgeable contributor please clarify the article on this? Wyresider (talk) 23:43, 19 January 2016 (UTC)

External links modified[edit]

Hello fellow Wikipedians,

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Question? Archived sources still need to be checked

Cheers.—cyberbot IITalk to my owner:Online 10:34, 28 January 2016 (UTC)

Reference cleanup and restructuring?[edit]

Please review this recent edit. The purpose is to have more consistent formatting, and to add links between footnotes and references. The mechanism was to add templates where they previously weren't used (though attempting not to change the visual presentation, where the presentation was already consistent). Jc3s5h correctly asserts that changing to templates unilaterally is contrary to WP:CITEVAR. Is there a consensus for or against this change?

(Note that there are also corrections and expansions to some of the citations mixed into this change. That's a separate issue.)

Nitpicking polish (talk) 18:35, 24 February 2016 (UTC)

Back when these citations were first cleaned up and put in the present format, I would have strongly opposed using citation templates. They had some horrible problems, like not being able to put too many citations on the page or else some of them wouldn't be rendered. The citation templates are better than they were, although I think there is a bit too much error checking. For example, putting February 29 for years that were leap years in the Julian calendar but not the Gregorian (like 1700) creates error messages. I'll go along with whatever consensus other editors come to. Jc3s5h (talk) 20:54, 24 February 2016 (UTC)

Inter Gravissimas (W. Spenser & R. T. Crowley, Trans.) paywalled. Is there an open source of this translation?[edit]

This is paywalled:

Is there another source for this translation of Inter Gravissimas?

--Geremia (talk) 20:41, 21 March 2016 (UTC)

Astronomers are subject to WP:RS and WP:V the same as anybody else[edit]