CalendarChange
CalendarChange[{year,month,day},calendar1,calendar2]
converts the date {year,month,day} given in calendar calendar1 into a date given in calendar calendar2.
CalendarChange[{year,month,day,hour,minute,second},calendar1,calendar2]
converts the given date {year,month,day,hour,minute,second}.
Details and Options
- To use CalendarChange, you first need to load the Calendar Package using Needs["Calendar`"].
- The following settings can be given for calendar1 and calendar2:
-
Gregorian Gregorian calendar Julian Julian calendar Islamic Islamic calendar Jewish Jewish calendar
Examples
open allclose allBasic Examples (8)Summary of the most common use cases

https://wolfram.com/xid/0dbtw3a018kw7oy6-iuyy1z
The Western calendar in current use is the Gregorian calendar. To convert a contemporary Western date to another calendar, use Gregorian for the contemporary Western date.
Israel obtained its independence on May 14, 1948. This finds the Jewish date:

https://wolfram.com/xid/0dbtw3a018kw7oy6-lcjf9

Because the Jewish calendar has a leap month preceding Passover, the Wolfram Language uses a numbering starting with Nisan, the month of Passover:

https://wolfram.com/xid/0dbtw3a018kw7oy6-bwltgd
Israel's independence was declared on the 5th of Iyar, 5708.

https://wolfram.com/xid/0dbtw3a018kw7oy6-gt0rlo
This finds the Western date corresponding to the 50th Jewish anniversary:

https://wolfram.com/xid/0dbtw3a018kw7oy6-cwuvnr


https://wolfram.com/xid/0dbtw3a018kw7oy6-ioiph3
Between 1582 and 1752, Catholic countries used the Gregorian calendar, while Britain and her colonies used the Julian calendar. To convert British and Catholic dates occurring between 1582 and 1752, it is necessary to change calendars from Julian to Gregorian.
George Washington was born February 22nd, 1732. In France, the date was:

https://wolfram.com/xid/0dbtw3a018kw7oy6-bf48rq


https://wolfram.com/xid/0dbtw3a018kw7oy6-b0jz7j
Voltaire was born on November 21st, 1694. In Great Britain the date was:

https://wolfram.com/xid/0dbtw3a018kw7oy6-mw8ibn


https://wolfram.com/xid/0dbtw3a018kw7oy6-i6966x
The Russian Orthodox Church still uses the Julian calendar. This finds the Western (Gregorian) date of Greek Orthodox Christmas 2000:

https://wolfram.com/xid/0dbtw3a018kw7oy6-fkfes


https://wolfram.com/xid/0dbtw3a018kw7oy6-cfeps2
You can find Islamic dates corresponding to Western (Gregorian) dates:

https://wolfram.com/xid/0dbtw3a018kw7oy6-bhz2bs

The Islamic calendar has the following months:

https://wolfram.com/xid/0dbtw3a018kw7oy6-i9a2b
The above date is, therefore, the 24th of Ramadan, 1420.

https://wolfram.com/xid/0dbtw3a018kw7oy6-wxxa0
The Western date for the beginning of Ramadan of the Islamic year 1420:

https://wolfram.com/xid/0dbtw3a018kw7oy6-bb245e


https://wolfram.com/xid/0dbtw3a018kw7oy6-him1d
Hours, minutes, and seconds are left unchanged by CalendarChange:

https://wolfram.com/xid/0dbtw3a018kw7oy6-g3ejoo


https://wolfram.com/xid/0dbtw3a018kw7oy6-e7ul1p

Possible Issues (1)Common pitfalls and unexpected behavior

https://wolfram.com/xid/0dbtw3a018kw7oy6-gxsjoo
Because it is a solar and lunar calendar (the year follows the seasons, and the months keep track of the phases of the moon), the Jewish calendar has an extra leap month 7 times every 19 years. This leap month occurs in spring the month preceding Passover, so it is appropriate to count the Jewish months starting with Nisan, the month of Passover, as follows:

https://wolfram.com/xid/0dbtw3a018kw7oy6-kmh5hw
Since the Jewish year begins in the fall, this numeration of months will not always follow an increasing order; that is, later dates in the same year may have a smaller number for the month:

https://wolfram.com/xid/0dbtw3a018kw7oy6-dw4kft


https://wolfram.com/xid/0dbtw3a018kw7oy6-h5x42k
