Talk:Leap week calendar

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Leap year rule[edit]

The rule determining whether a year has 53 weeks, will be more complicated than a leap year rule, especially if the variation of the equinox and solstice dates is less than two weeks.

Incorrect. Gregorian-level accuracy can be achieved with this simple rule: Leap weeks are added in multiples of 5 except for multiples of 40 not divisible by 400.

Yes, but this rule gives rise to a variation in excess of two weeks see [[1]]. That is why I added the especially clause. It is also a slightly more complicated than the Gregorian rule, from using a 40 rather than 100 year period for the exceptions. Karl (talk) 13:11, 25 January 2013 (UTC)
Inherently a leap week calendar has greater equinox or solstice wobble than a leap day calendar, but that can be minimized by using a leap rule that distributes the leap years as smoothly as possible, which is simpler to do anyway. Furthermore, there are astronomical advantages in distributing the leap years symmetrically within each leap cycle, which is also no more complex to accomplish, see Symmetrical Leap Cycles. If you are really determined to use a 400-year leap cycle, and I don't recommend it because it yields a calendar mean year that is slightly too long relative to the mean northward equinoctial year that is typically taken as the target, then there must be 71 leap weeks per cycle. It can't be a perfectly symmetrical cycle because 400 is an even number, but it can be made almost perfectly symmetrical and leap years smoothly distributed by the simple single-step leap rule: Year y is leap only if the remainder of (71 y + 200) / 400 < 71. Kalendis (talk) 21:18, 1 April 2011 (UTC)
That is, year y is a leap year only if "mod(71y+200,400)<71" is true. Cup o' Java (talkcontribs) 21:25, 24 January 2013 (UTC)

Equal complexity to the Gregorian calendar's leap day rule.

I was just about to make the same coment. Let's remove this line, shall we? By the way, I do wonder what the equinoxes and solstices have to do with it. Jimp 7Sep05
Normally a calendar mean year is designed to approximate an equinoctial or solstitial mean year to minimize long-term drift of the calendar relative to the target equinox or solstice. In the present era the only sensible choices for a simple fixed arithmetic leap cycle are the mean northward equinoctial year or the mean north solstitial year, as they are currently stable. By contrast, the mean southward equinoctial year and south solstitial year are currently getting progressively shorter, see: The Lengths of the Seasons (on Earth). Kalendis (talk) 21:22, 1 April 2011 (UTC)
The whole concept of leap week has a problem that equinoxes and solstices are not on the same day every year. Depending on which calendar to use, they can vary from 3 days up to 19 days. It can be a significant problem in computing Easter as March equinox has to be on March 21. --Quest for Truth (talk) 14:48, 22 March 2009 (UTC)
False. The equinox does not, in fact, have to be March 21, and, in fact, it is not always March 21 in the Gregorian calendar. Victor Engel (talk) 15:42, 30 March 2011 (UTC)
True, there is greater variation in the dates of equinoxes and solstices (but, as noted above, variation exists in the Gregorian calendar) but how big a problem is this? Easter is unimportant to two-thirds of the World's population and, as for the rest, I'm sure they won't be too fussed if it were moved from the first Sabbath day once the Moon hath waxen full since the equinox of March to, say, the eighth of April (if they even notice). JIMp talk·cont 07:49, 22 January 2013 (UTC)

External links: ISO leap years link wrong[edit]

The lnk goes to the CCC&T site, and lists leap weeks according to that calendar. This is wrong because different leap year rules were used to derive the list (CCC&T uses unspecified astronomical data - ISO 8601 is derived from the underlying gregorian year) and because the CCC&T calendar begins on Sunday rather than Monday, meaning that start dates cannot be matched.

Renaming Leap Week Calendar to Week Calendar[edit]

What is the reason for renaming the article? I note that related links in the newly renamed article still refer to "Leap Week Calendar" rather than "Week Calendar". I see no compelling reason to have changed the name, but maybe I'm missing something. Victor Engel (talk) 14:26, 31 March 2011 (UTC)

I agree. A calendar that uses a leap week is a leap week calendar, a calendar that uses a leap day is a leap day calendar, and a calendar that uses a leap month is a leap month calendar. One can equally well use a skip week, skip day, or skip month calendar with the same duration leap cycles, it doesn't change how many years are long vs. short. Leaps per Cycle = Years per Cycle minus Skips per Cycle. Kalendis (talk) 21:09, 1 April 2011 (UTC)

There is no adequate week calendar article yet. Leap week calendars are a special kind of week calendars, i.e. all leap week calendars are week calendars, but not all week calendars have a leap week. Instead of writing a new article from scratch it made sense to me to extend this one (and therefore first rename, i.e. move it).
WP:PRECISION quoted in the revert of the move doesn’t apply, because the change is not about a controversial title or something like that, but founded in changing the scope.
It's not controversial to you because you dreamed it up. Can you even cite any references that use the term "week calendar"? Victor Engel (talk) 04:14, 2 April 2011 (UTC)
Lastly, although I do use the term some people object to “leap week”, “leap week year” and “leap week calendar”, since they only consider “leap” valid in combination with 29 February. See the version history of ISO week date that resulted in “long year”.
That, of course, presumes the calendar under consideration even has such a date as 29 February. It may not. I'm not sure what relevance a discussion on ISO week date has. As mentioned in that article, that is a special case of a leap week calendar, so there may be things specific to it. On the flip side, I don't think it's a given, either, that a leap week calendar must have weeks consisting of 7 days. Suppose a calendar was made up of 6 day weeks. A short year then might have 60 weeks, and a long year 61 weeks. In such a calendar, week 53 really has no special meaning at all. Victor Engel (talk) 04:30, 2 April 2011 (UTC)
Anyhow, I actually have more important things to care about at the moment. — Christoph Päper 23:31, 1 April 2011 (UTC)
Yeah, you said something like that before, and then proceeded to amend the article. Victor Engel (talk) 04:14, 2 April 2011 (UTC)
FWIW, “week calendar” is better established than “leap week calendar”: “week calendar” wins Google battle, over two magnitudes.Christoph Päper 13:00, 2 April 2011 (UTC)


One of the advantages is apparently "For leap week calendars without months, each date of the year can be completely specified with three data (week, weekday, year), instead of four (weekday, month, ordinal day, year)." Call me old fashioned, but I only need 3 pieces of data NOW to reference any day in any year. Day of month, month, and year. MrZoolook (talk) 00:28, 14 January 2013 (UTC)

I agree. This should be changed. Feel free to go a head and be bold! –Cup o' Java (talkcontribs) 01:27, 15 January 2013 (UTC)
That's what I was thinking. Jimp 10:38, 19 March 2014 (UTC)

Complicated leap-year rules[edit]

Says the article "Leap-year rules are usually more complicated than the Gregorian rule—except for the ISO Week Date, which follows the Gregorian calendar, having no leap-year rule of its own.".

What kind of exception is this? You have to figure out what day the Gregorian year starts on. To do that you have to use the Gregorian rule to figure out leap years but your not finished, you then have to figure out what day the Gregorian year would start on. It is a rule of its own, a very complicated rule.

There is, however, a simple rule which gives average years of a reasonable length (I don't know whether any notable proposal suggests it, though). We could switch the 4, 100 & 400 of the Gregorian with 5, 40 & 400. This rule is just as simple and gives a year just as long. Jimp 10:38, 19 March 2014 (UTC)