From: Chong Yidong Date: Sun, 9 Aug 2009 23:39:59 +0000 (+0000) Subject: * calc.texi (Date Forms): Fix typos. X-Git-Tag: emacs-pretest-23.1.90~1900 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=4c39f404d52c888bd314a3ffed4c6306537343fe;p=emacs.git * calc.texi (Date Forms): Fix typos. --- diff --git a/doc/misc/ChangeLog b/doc/misc/ChangeLog index 0ec28f3c160..e0fbe264175 100644 --- a/doc/misc/ChangeLog +++ b/doc/misc/ChangeLog @@ -1,3 +1,7 @@ +2009-08-09 Colin Williams (tiny change) + + * calc.texi (Date Forms): Fix typos. + 2009-08-08 Glenn Morris * org.texi (Agenda commands): Restore clobbered change. diff --git a/doc/misc/calc.texi b/doc/misc/calc.texi index 4653a9446a4..49a5260af6c 100644 --- a/doc/misc/calc.texi +++ b/doc/misc/calc.texi @@ -11093,29 +11093,29 @@ days 0 and @mathit{-1} respectively in Calc's internal numbering scheme. @cindex Julian day counting Another day counting system in common use is, confusingly, also called -``Julian.'' The Julian day number is the numbers of days since -12:00 noon (GMT) on Jan 1, 4713 BC, which in Calc's scheme (in GMT) +``Julian.'' The Julian day number is the numbers of days since +12:00 noon (GMT) on Jan 1, 4713 BC, which in Calc's scheme (in GMT) is @mathit{-1721423.5} (recall that Calc starts at midnight instead of noon). Thus to convert a Calc date code obtained by unpacking a date form into a Julian day number, simply add 1721423.5 after compensating for the time zone difference. The built-in @kbd{t J} command performs this conversion for you. -The Julian day number is based on the Julian cycle, which was invented +The Julian day number is based on the Julian cycle, which was invented in 1583 by Joseph Justus Scaliger. Scaliger named it the Julian cycle -since it is involves the Julian calendar, but some have suggested that +since it involves the Julian calendar, but some have suggested that Scaliger named it in honor of his father, Julius Caesar Scaliger. The -Julian cycle is based it on three other cycles: the indiction cycle, -the Metonic cycle, and the solar cycle. The indiction cycle is a 15 -year cycle originally used by the Romans for tax purposes but later -used to date medieval documents. The Metonic cycle is a 19 year -cycle; 19 years is close to being a common multiple of a solar year -and a lunar month, and so every 19 years the phases of the moon will -occur on the same days of the year. The solar cycle is a 28 year -cycle; the Julian calendar repeats itself every 28 years. The -smallest time period which contains multiples of all three cycles is -the least common multiple of 15 years, 19 years and 28 years, which -(since they're pairwise relatively prime) is +Julian cycle is based on three other cycles: the indiction cycle, the +Metonic cycle, and the solar cycle. The indiction cycle is a 15 year +cycle originally used by the Romans for tax purposes but later used to +date medieval documents. The Metonic cycle is a 19 year cycle; 19 +years is close to being a common multiple of a solar year and a lunar +month, and so every 19 years the phases of the moon will occur on the +same days of the year. The solar cycle is a 28 year cycle; the Julian +calendar repeats itself every 28 years. The smallest time period +which contains multiples of all three cycles is the least common +multiple of 15 years, 19 years and 28 years, which (since they're +pairwise relatively prime) is @texline @math{15\times 19\times 28 = 7980} years. @infoline 15*19*28 = 7980 years. This is the length of a Julian cycle. Working backwards, the previous