The perpetual calendar
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From: PaulJK on 22 Feb 2010 00:39 Peter Moylan wrote: > Halmyre wrote: > >> I just wish they'd settle on a date for Easter and be done with it. > > The present system might sound complicated, but it's a consistently > reliable method - at least in Australia - for predicting the arrival of > the first really rainy weekend in the year. This ensures that all the > people who go camping for the long weekend will be rained out, year > after year. Well, in New Zealand that prticular function is performed by Christmas. Often, the rain keeps regularly returning until the end of January/ beginning of February when the kids go back to school after the end of summer holidays. pjk
From: PaulJK on 22 Feb 2010 01:48 Andrew Usher wrote: > Brian M. Scott wrote: > >>>>> And the first day of the week is Sunday, not Monday - that >>>>> is an incontrovertible fact. >> >>>> Don't be ridiculous: it's merely a convention. For many of >>>> us Monday is unquestionably the first day of the week. >> >>> It's historically true. No one questioned it before modern times. >> >> Apparently you're not familiar with the Slavic and Baltic >> day-names. For that matter, Sunday is the first day in >> Jewish tradition for the same reason that Monday is the >> first day for many of us today. > > The Slavic and Baltic day names come from Greek tradition (itself > aberrant), not from Western tradition where it was always Sunday. Where did you get that nonsense? If you actually checked the Slavic/Baltic and Greek day names you'd find that they obviously do NOT follow the same tradition. Hey, what a surprise, Greek day names treat Sunday as the day number one! pjk > In addition, it's probably true that the astrological week came before > the Jews adopted it. > > Andrew Usher
From: Transfer Principle on 22 Feb 2010 01:58 On Feb 18, 8:13 pm, Andrew Usher <k_over_hb...(a)yahoo.com> wrote: > Owing to the inconveniences which attend the shifting of the calendar, > and attempting in passing to create a more perfect Church calendar, I > say the following: The notion of calendar reform has appeared on sci.math from time to time. Some people may argue that the debate between those who defend the standard Gregorian calendar and those who wish to reform it is analogous to the debate between the standard set theorists and the so-called "cranks." I'd argue that calendar reform would fit Underwood Dudley's "eccentric" category more than the "crank" category. But then again, the OP of this thread (Andrew Usher) has already been considered a "crank" due to his views on the standard ZFC set theory. Compared to some calendar reformer's proposal's, Usher's is relatively tame. He only proposes a new leap year rule and new dates for the Christian holidays, as opposed to more radical proposals (such as the 13-month calendar proposal mentioned later in this thread). > 1. That Christmas day should be fixed to a Sunday, and this should be > the Sunday between Dec. 21 and 27, and that in all civilised countries > the Monday should be considered a holiday, or the Saturday if not > normally. On one hand, the notion of Christmas always falling on a Sunday sounds appealing, since it's the Christian sabbath (and thus Christians are already in church anyway). Some of the previous calendar reformers have also proposed having Christmas always fall on a Sunday, since, as Usher points out, it allows the holiday to fall on a three-day weekend and prevents workers from wanting to take extra days off when Christmas is mid-week. On the other hand, some workers are going to take off extra days anyway. According to a certain game show (the second time I've referenced game shows in an Usher thread), Christmas (and not Thanksgiving as some may believe) is the most heavily traveled holiday in the USA. Travelers are often forced to leave several days before Christmas because the airlines are booked on the days closer to the holiday. In years in which Christmas is mid-week, the workers are likely to take those extra days off anyway, but when Christmas is on a Sunday as per Usher's proposal, workers don't necessarily wait until Friday, December 23rd at 5PM to begin their holiday travel. So workers may be as likely to take off extra days under Usher's proposal as they are under the current Gregorian calendar. (Also, Sunday Christmases often cause headaches for school calendar planners as well. Some schools actually have school all the way up until Friday, December 23rd, and then have low attendance rates the last few days. One could have school end a full week before Christmas instead, but then the standard two-week winter break might end too close to New Year's Day, or even before, since a December 21st Usher Christmas would result in school resuming on Monday, December 29th, which is before New Year's Day.) Therefore I'm of two minds regarding the Usher Christmas Day. > 2. That similarly Easter day should be fixed to the Sunday which is 15 > weeks following Christmas. Many schools and universities no longer tie their spring break holidays to Easter since it floats so much. They often prefer a break at a fixed point in the spring semester. Therefore, I agree with the Usher Easter more than the Usher Christmas. > 3. That the leap year rule be changed to have a leap year occur every > fourth save that it be delayed when the leap year would start on a > Thursday, and that this gives 7 leap years in every 29, which is near > enough. There's a huge problem with the Usher leap year plan here. I can see why Usher would want to avoid leap years starting on Thursdays, since Easter, being 15 weeks after Christmas, would fall on April 4th such years, which is outside of the April 5-11 range given by Usher elsewhere in this thread. But suppose the Usher plan had been implemented in 2004, which was the last time a leap year started on Thursday. Thus the Usher leap year would have been 2005 instead. Now let's look at a table of Usher New Year's Days and leap years: 2004: Thursday 2005: Friday (leap year) 2006: Sunday 2007: Monday 2008: Tuesday 2009: Wednesday (leap year) 2010: Friday 2011: Saturday 2012: Sunday 2013: Monday (leap year) 2014: Wednesday 2015: Thursday 2016: Friday 2017: Saturday (leap year) 2018: Monday 2019: Tuesday 2020: Wednesday 2021: Thursday (common year) 2022: Friday (leap year) 2023: Sunday And now we see the problem. The resulting leap year cycle isn't 7 leap years in 29 years, but rather 4 leap years in only 17 years. This is because by skipping Thursday leap years, Usher unwittingly skipped Tuesday and Sunday leap years as well! And so the resulting mean year length is only 365+4/17 = 365.2352941 days, which is less accurate than the Gregorian leap year rule. The idea of having occasional five-year periods between leap year's isn't new. Wikipedia mentions the Jalaali calendar, billed as the most accurate solar calendar in the world, which has 8 leap years in 33 years, giving a mean year length of 365+8/33=365.2424... years: http://en.wikipedia.org/wiki/Iranian_calendar > 4. That the perpetual calendar can be made, by considering the first > day of the year of weeks to occur on the Sunday after the Assumption, > and if this is the first possible calendar day, it is called week 1, > and otherwise week 2, and every year runs through week 53. And this > calendar ensures that everything can be fixed to a day of a certain > week, in particular the American Thanksgiving must be made 31 days > before Christmas. There is already a similar week-numbering scheme: http://en.wikipedia.org/wiki/ISO_week_date Of course, the ISO week 1 occurs near New Year's Day, which is unacceptable to Usher since he wants to avoid starting the count during his 15 weeks between Christmas and Easter. So he chose a different starting point. Also, the ISO weeks start on Monday whereas Usher weeks start of Sunday (but this was discussed by others elsewhere in the thread). Notice that the current USA Labor Day (first Monday in September) already occurs exactly 11 weeks and three days before Usher Thanksgiving. As Usher points out later, this is convenient for college football, which traditionally began on Labor Day weekend and ended on Thanksgiving, with enough time to play 11 games in between. (The recent practice of playing 12 games instead of 11 occurred because in a recent year when Labor Day and Thanksgiving were 12 weeks and three days apart, colleges scheduled an extra game, then kept on scheduling 12 games even when the period between the two holidays switched back to 11 weeks and three days.) Also, the current USA Memorial Day (last Monday in May) already occurs exactly seven weeks and one day after the Usher Easter. In other words, it's always Whit Monday. (For those who are tired of all these USA holiday references, note that the UK Spring Bank Holiday occurs on the same day as USA Memorial Day, while the UK Summer Bank Holiday occurs exactly one week before USA Labor Day.) > 6. This is surely the best possible arrangement that can be made, > without disturbing the cycle of weeks or that of calendar days > inherited from the Romans. I'm not sure whether this is the best possible calendar, but it's certainly an interesting proposal.
From: R H Draney on 22 Feb 2010 03:34 Transfer Principle filted: > >The notion of calendar reform has appeared on sci.math from time >to time. Some people may argue that the debate between those who >defend the standard Gregorian calendar and those who wish to >reform it is analogous to the debate between the standard set >theorists and the so-called "cranks." I'd argue that calendar >reform would fit Underwood Dudley's "eccentric" category more >than the "crank" category. If you want a crank, find the person who came up with Daylight Saving Time.... Then find his successor who decided that DST should apply for more of the year than "Standard" time....r -- "Oy! A cat made of lead cannot fly." - Mark Brader declaims a basic scientific principle
From: Ruud Harmsen on 22 Feb 2010 03:50
Sun, 21 Feb 2010 17:01:46 -0000: jimp(a)specsol.spam.sux.com: in sci.lang: >In sci.physics jmfbahciv <jmfbahciv(a)aol> wrote: >> Andrew Usher wrote: >>> Mike Barnes wrote: >>>> Adam Funk <a24061(a)ducksburg.com>: >>>> >From man 5 crontab: >>>>> When specifying day of week, both day 0 and day 7 will be >>>>> considered Sunday. BSD and AT&T seem to disagree about this. >>>> But they presumably agree that day one is Monday. >>> >>> But 0 is the start of computer indexing - at least in real programs. 0 >>> = Sunday. >>> >> Where do you get that idea? >> >> /BAH > >From crontab and array indexes. C. -- Ruud Harmsen, http://rudhar.com |