Blinking snake



devn - Show deviation between Gregorian and Julian Style calendars


devn [-h?vbuIpV] <date(s)> ... ...


Devn calculates the difference (“deviation”) between the Julian Calendar and the Gregorian Calendar, in whole days. Through February 29, 2100, this difference is 13, after which it is 14. To convert from the Gregorian calendar to the Julian (or what would be Julian if we were still running it) calendar, we subtract 13 (“-13”) from the current date. Reverse the sign to convert from Julian to Gregorian. Any date may be input, and for each input date the deviation will be printed; with -v set, it tells more. The zero point is 00:00:00 Mar 1, 200 CE. From that time until 23:59:59 Feb 28, 300 CE, the deviation is 0. Refer to “jug” and “grj” for a discussion of why the zero point occurs then instead of at the time of adoption of the Gregorian calendar in 1582.


Help, stdout.
Help, stderr.
Print years in verbose output as 2 BC instead of -1.
Print the period of deviation; i.e., date is input as a deviation (13 or -13) and the beginning and ending dates of that deviational period are printed. Note that the -u must be the last argument before deviations are entered.
Obtain dates/deviations from <file> instead of from the command line.
If devn is reading from stdin or /dev/tty, and you have specified this option, it will prompt (“devn: ”) before reading.
Print version date and die.


$ devn
$devn -v
11/26/1996  jug (julian -> gregorian) = +13 days.
	    grj (gregorian -> julian) = -13 days.
$ devn -u -13
3/1/1900 to 2/29/2100
$ devn -vu -13
Deviation -13: 3/1/1900 to 2/29/2100
Deviation +13: 3/1/-1500 to 2/29/-1400
$ devn -v 2/28/-100
02/28/-0100  jug (julian -> gregorian) = -3  days.
             grj (gregorian -> julian) = +3  days.
$ devn -v 3/1/-100
03/01/-0100  jug (julian -> gregorian) = -2  days.
             grj (gregorian -> julian) = +2  days.


The ? in the -? must be escaped (preceded by a \) to prevent interpretation as a metacharacter by some shells.


ncal(I), easter(I), jug(I), weekday(I), jday(I), grj(I)




Ivan Van Laningham. If you would like the C source, email me.

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