4 Apr
2011
4 Apr
'11
8:11 p.m.
Rich Alderson wrote:
From: Jerome H. Fine
Sent: Monday, April 04, 2011 5:49 PM
You have forgotten to take into account the fact that the Gregorian
calendar was not adopted in by English speakers until 1752, by which
time an 11th day had to be dropped from the calendar. While the Catholic
countries in Europe adopted the Gregorian calendar in 1582, dropping 10
days in October, the English and their colonies took another 170 years,
and dropped 11 days in September of that year.
So any time-warping calendar program needs to take not only the date but
the location into account.
In addition, other countries such as Russia adopted the Gregorian Calendar
at a much later date. I am not sure when the US adopted the Gregorian
Calendar, but it was probably around the same time.
After considering how few dates will be used prior to 1900, I concluded
that the
Gregorian Calendar can be used as a common set of dates rather than
making the
different set of exceptions for all of the different countries. And
prior to 1582,
the proleptic Gregorian Calendar would provide a continuous set of dates
without
any gaps.
Plus, supporting dates prior to 1972 was really in response to Don North,
although I suspect it was more of an April Fool's suggestion.
Don North
wrote:
Actually I'd be more interested in Y1K support since I am using
an 11/34 as the navigational computer in my time machine, and it
only goes back in time.
Already taken into account. The only question is how far back?
While my initial start year was around 9999 BCE, I settled for the
year 1588 CE (= 1972 - 3 * 128). Since the Gregorian Calendar
started in 1582, there would not be any question of needing the
proleptic Gregorian Calendar dates (dates which would be in effect
if the Gregorian Rules had been used prior to 1582). However,
if you need all of the dates for positive years staring with 1 CE, that
can easily be accommodated.
It is far better to use Julian days (not related to the
Julian calendar
which the Gregorian revised), and calculate from there to dates on any
shorter-term calendar.
Switching to Julian Days would provide a better solution, but the majority
of Common Era (CE) dates are expressed via the more familiar months
of January to December with a day number and a CE year. I suspect
that the confusion of Julian Days would not be worth the extra precision.
The imposition of using a proleptic Gregorian Calendar for dates in
countries
which had not switched should not be a huge burden if dates prior to 1900 CE
are rarely needed, let alone used.
If in the future, Julian Days prove to be a popular request for the
date, then
code could be added for its support.
Jerome Fine