Talk:Maya calendar/Archives/2005/December

Calculating the Tzolkin date portion

The text of this section of the article now reads:

The Tzolkin date is counted forward from 4 Ahau. To calculate the numerical portion of the Tzolkin date, we must add 4 to the total number of days given by the date, and then divide total number of days by 13. (4 + 1383136) / 13 = 106395 and 5/13 This means that 106395 complete 13 day cycles have been completed, and the numerical portion of the Tzolkin date is 5. To calculate the day, we divide the total number of days in the long count by 20 since there are twenty day names. 1383136 / 20 = 69156 and (16/20) This means 16 day names must be counted from Ahau. This gives Cib. Therefore, the Tzolkin date is 5 Cib.

An anonymous person added this text:

*** This is not quite right: the remainder, when you divide by 13, ranges from 0 to 12. But the Tzolkin dates go from 1 to 13. So you should add 3 to the day number, find the remainder when dividing by 13, and then add 1. ***

The change, as it was formatted by that anonymous person, is inappropriate for the article space. However, the person has a point. What if the remainder had been zero? For example, what if the day were 1383131, and the same calculation were performed? It strikes me that a change of one sort or another is needed here.—GraemeMcRae^talk 04:44, 19 November 2005 (UTC)

The maths is by using the modulo 13 of a number. Basically you are subtracting as many 13's as possible from the original number. Whatever is left is what you use to advance the count from the base date. If the remainder was 0, you don't advance that portion of the date. Dylanwhs 09:26, 9 December 2005 (UTC)

Accurate calendars

It's been reported the Maya caledar was the most accurate until the Gregorian. Trekphiler 22:51, 8 December 2005 (UTC)

True, that is a statement frequently encountered, and perhaps equally often it is claimed that the Maya calendar was/is much more accurate than our present Western one. However, both of these statements are untrue, or at least need to be highly qualified. As shown in this article, the portion of the Maya calendar which approximated the tropical year took account of 365 full days, and the calendar itself had no mechanism or adjustment such as 'leap years' which would keep it in synch with the "true" year. However, even though the Maya did not see fit to update their calendar with the appropriate compensatory mechanisms, it is evident that they were well enough aware of its gradual precession for they would from time to time realign certain ceremonies which were supposed to correspond with astronomical and seasonal events- but did not adjust the calendar itself. I think that when people (rather too loosely) speak of the Maya calendars' "remarkable accuracy", what they are really referring to is their prowess in observational and mathematical calculations, with which they could indeed pinpoint certain astronomical events with considerable accuracy. For eg, by extending the number of observation cycles of the moon (as is done in the Dresden Codex's eclipse tables) to 405 lunar months, this corresponded to a mean synodic month of 29.53086, whereas the modern mean value is 29.53059. This is a little more accurate than the corresponding Ptolemaic calculation, for example. However, it should be noted that these calculations were done more so to "fit in" with numbers and cycles they found significant, rather than for accuracy's sake alone, and that the calendars themselves were not adjusted. Perhaps it could be said that they possessed highly accurate almanacs, rather than calendars.--cjllw | TALK 00:40, 9 December 2005 (UTC)