Talk:Date of Easter

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Merge with Easter Controversy article?

I think that this article's history section should be fairly brief. Merger would expand it to unwieldy lengths. I vote for keeping the Easter Controversy article separate, and removing the tag proposing the merger.--Mockingbird0 (talk) 04:29, 8 July 2011 (UTC)[reply]

Better in my view not to merge them, and summarize Easter Controversy here. Tom Harrison ^Talk 11:31, 26 March 2012 (UTC)[reply]

This article is basically mathematical. It should indicate clearly for which flavor of Easter a particular formula is applicable, but the reasons historical or otherwise why there are conflicting formulas belong to Easter Controversy. (DPL 6 April 2012) — Preceding unsigned comment added by 41.5.23.67 (talk) 09:29, 6 April 2012 (UTC)[reply]

I've removed the tag proposing Easter controversy merge as per consensus. What about Ecclesiastical full moon? --- DoctorKubla (talk) 14:51, 4 May 2012 (UTC)[reply]

I'll take that as a no, particularly since you didn't give any reasons for. — LlywelynII 01:49, 4 February 2013 (UTC)[reply]

Meeus Julian algorithm examples for 2008 and 2009

2008 and 2009 examples in the Julian Algorithm section are not correct considering the Gregorian calendar. They are not even on Sundays. — Preceding unsigned comment added by Claytom (talk • contribs) 02:02, 6 May 2012 (UTC)[reply]

So what? Jc3s5h (talk) 14:00, 6 May 2012 (UTC)[reply]

Notes to Excel formulas

Both formulas on article page work correct only from 1900 to 2203 in the 1900 date system and provide only the Gregorian Easter Sunday dates

Calculate Gregorian Easter date

The actual state is a reduction to <100 characters with full functionality from 1900 to 9999

date system	Excel formula
1900	=FLOOR((5&-A2)+97%MOD(18.998MOD(A2+8/9,19)+INT(68%INT(A2%)-INT(A2%/4)-5/9),30),7)-34 or longer =FLOOR((4&-A2)-5+97%MOD(18,998MOD(A2+8/9;19)+INT(68%INT(A2%)-INT(A2%/4)-5/9);30);7)+1
1904	=FLOOR((4&-A2)-6+97%MOD(18,998MOD(A2+8/9;19)+INT(68%*INT(A2%)-INT(A2%/4)-5/9);30);7)+2
190x	=FLOOR((4&-A2)-DAY(5)+97%MOD(18,998MOD(A2+8/9;19)+INT(68%*INT(A2%)-INT(A2%/4)-5/9);30);7)+DAY(1)

Excel community: http://www.online-excel.de/fom/fo_read.php?f=1&h=58861&bzh=72926&ao=1#a123x

The Gregorian Easter period began 1583 and not 1900 - and that's why it must be enhanced (1900 date system).

=A2&TEXT(FLOOR((5&-A2-(A2%<19)/5%%)+97%*MOD(18.998*MOD(A2+8/9,19)+INT(68%*INT(A2%)-INT(A2%/4)-5/9),30),7)-34,"-MM-DD")

Notice: This formula provides the same results like Gauss from 0001-9999, you could enhance it again with starting =TEXT(A2,"0000")&...
17:42, 23 June 2013 (UTC)

Calculate Julian Easter date

As date: The following works from years 1900 to 9999 (1900 date system)

=(A2&TEXT(FLOOR((5&-1908-MOD(A2,28))+MOD(19*MOD(A2,19)-14,30),7),"-M-D"))-35

As text: The following works from years 0001 to 9999 (1900 date system)

=TEXT(A2,"0000")&TEXT(FLOOR((4&-1908-MOD(A2,28))+MOD(19*MOD(A2,19)-15,30)-4,7),"-MM-DD")

Combination of Julian/Gregorian Easter date

As YYYY-MM-DD text: The following works from years 0001 to 9999 and any breakpoint from 1 to 9999 (here it is 1583), taking 1900 date system

=TEXT(A2,"0000")&TEXT(IF(A2<1583,FLOOR((4&-1908-MOD(A2,28))+MOD(19*MOD(A2,19)-15,30)-4,7),FLOOR((5&-A2-(A2%<19)/5%%)+97%*MOD(18.998*MOD(A2+8/9,19)+INT(68%*INT(A2%)-INT(A2%/4)-5/9),30),7)-34),"-MM-DD")

Frank Schneider, 08:55, 5 November 2013 (UTC)--

First two Excel formulas of main page have a lot of restrictions - is it possible to replace them? 22:10, 30 September 2013 (UTC) — Preceding unsigned comment added by 85.199.76.112 (talk)

I added the universal formula. Frank Schneider, 08:55, 5 November 2013 (UTC)--

Addition to table, claiming regular pattern

Is the table addition in this edit by User:Q5968661 comprehensible and sufficiently connected to the remainder of the article that readers will understand why it is included? Is this table useful to readers, and therefore merit inclusion? Is "regular pattern" a correct and useful titile for that portion of the table? Jc3s5h (talk) 19:54, 3 March 2013 (UTC)[reply]

Simplify or explain. The table is confusing, but if additional explanation were offered it would make more sense. Alternatively, the article could include a simplified walkthrough of what all of those dates mean for a single year. Andrew³²⁷ 19:21, 5 March 2013 (UTC)[reply]
This makes sense. Perhaps split into two tables preceded by explanations? Comparisons should still be easy enough for reader, if tables are in proximity to each other. — daranz [ t ] 20:35, 14 March 2013 (UTC)[reply]

Mental arithmetic

>> step1 needs to be bracketed to clarify it is the +29 that is conditi0onal on y mod 19 = 5 or 16. >> and some clarification is also needed on what mod 30 really means here, since mathematically it should be in the range 0-29 or (sometimes) -14..15 but in the samples 55 mod 30 = 25 but 88 mod 30 = -2. A1jrj (talk) 14:01, 19 May 2013 (UTC)[reply]

Step one: using 45 - (y mod 19 × 11) mod 30 + 29, if y mod 19 = 5 or 16, to determine the date of PFM (PFMd).

Step two: using (y mod 100 + [y mod 100/4] + c + PFMd) mod 7 to determine the day of PFM (dPFM).

Step three: using PFMd + 7 - dPFM to determine the date of Easter (if the result > 31 the month = April).

where c = 3 for years 1900 ~ 1999, c = 2 for years 2000 ~ 2099, and c = 0 for years 2100 ~ 2199.

Take a few examples:

The year 2000 mod 19 = 2000 - 1995 = 2000 - 2000 + 5 = 5 hence 5 × 11 mod 30 = 55 - 30 = 25, so PFMd = 45 - 25 + 29 = 49 (Apri 18), and 2000 mod 100 = 0 hence dPFM = (0 + 0 + 2 + 49) mod 7 = 0 + 0 + 2 + 0 = 2 (Tuesday), so Easter Sunday = 49 - 31 + 7 - 2 = 18 + 5 = 23 April.
The year 1992 mod 19 = 16 hence 16 × 11 mod = 26, so PFMd = 45 - 26 + 29 = 48 (April 17), and 1992 mod 100 = 92 hence dPFM = (92(8) + [92(8)/4] + 3 + 48) mod 7 = 1 + 2 + 3 + 6 - 7 = 5 (Friday), so Easter Sunday = 48 - 31 + 7 - 5 = 17 + 2 = 19 April.
The year 2117 mod 19 = 2100 - 2090 + 17 - 19 = 2100 - 2100 + 10 - 2 = 8 hence (8 × 11) mod 30 = 88 - 90 = -2, so PFMd = 45 - (-2) = 47 (April 16), and 2117 mod 100 = 17 hence dPFM = (17 + [17/4] + 0 + 47) mod 7 = 3 + 4 + 5 - 7 = 5 (Friday), so Easter Sunday = 47 - 31 + 7 - 5 = 16 + 2 = 18 April.

So it is very easy to determine the date of Easter! --Q5968661 (talk) 10:06, 8 March 2013 (UTC)[reply]