Mike Schwab wrote: <begin snippet> Actually, the Islamic calendar is 12 lunar months of 29.5 days on average. So it is shorter than a solar year by about 11 days and the 1st day of the year cycles through the solar year about every 34 or so years. </end snippet>
and his point in fact makes mine. In the standard Moslem view the aseasonality of the Islamic lunar calendar is one of its chief merits. Moslems have designed lunisolar calendars. The Djalali calendar designed in the 11th century by the Persian poet and astronomer Omar Khayyam and his colleagues is at least as good a lunisolar calendar as our much later Gregorian one; and a variant of this calendar is the one used for secular purposes in Iran today. But Persian Moslems, be they Sunni or Shia, use the Islamic lunar calendar for religious purposes. Like other Moslems they perceive it to be fairer. Its aseasonality means that the considerable rigors of the 9th penitential month of Ramazam/Ramadan are not aggravated for some Moslems because it always falls in high summer and mitigated for other Moslems because it always falls in the depths of winter. A standard, day-serial-number (DSN) scheme is appropriate, indeed necessary for the internal representation of dates in computer systems. External date representations now vary widely at different places on the surface of this small planet, and since they serve very different purposes this diversity is likely to persist. It need not, however, be problematic. Presentation services can format dates that are to be printed or displayed in many different ways. To support any such display scheme d, one need write only two trivial subroutines: one that performs the conversion d==>DSN and another that performs the conversion DSN==>d; conversion between two such display schemes d, D is then accomplished by the sequence d==>DSN, DSN==>D. N such schemes can be supported by writing 2N subroutines, and a new scheme can be added by writing just two more of them (and reassembling a table). To summarize now, the notion of a universal external date representation is, I think, chimerical; and it would be easy to stigmatize as provincial and authoritarian too. Respect for seasonality is certainly desirable in some contexts and, as I have tried to make clear, undesirable in others. Moreover, if our species survives and undertakes space travel even the notion of a month/lunation will have to be discarded as parochial. There is a planet in our solar system---Its identification is left as an exercise for the interested reader---that revolves about the sun in a period that is shorter than the period of its rotation on its own axis. Months being longer than years there, its inhabitants' notion of a month would surely be very different from ours. John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN
