[vox-tech] Easiest way to calculate date in 100 ns increments?

[Rick Moen]

Quoting Mark K. Kim (lugod at cbreak.org):

> BTW, `cal 9 1752` may amuse some people:
> 
>    $ cal 9 1752
>       September 1752
>    Su Mo Tu We Th Fr Sa
>           1  2 14 15 16
>    17 18 19 20 21 22 23
>    24 25 26 27 28 29 30
> 
> 
> 
>    $ _
> 
> Somehow changing the locale doesn't change `cal`'s behavior.  It should,
> though.  A bug, perhaps?

Country code rather than locale, I think, and it might depend on the
_implementation_ of cal.  


BSD cal's manpage includes:

     -s country_code
             Assume the switch from Julian to Gregorian Calendar at the date
             associated with the country_code.  If not specified, ncal tries
             to guess the switch date from the local environment or falls back
             to September 2, 1752. This was when Great Britain and her
             colonies switched to the Gregorian Calendar.


Whereas gcal includes:

`--gregorian-reform=1582|1700|1752|1753|ARGUMENT'
     Set the period which was skipped during the Gregorian Reformation.
     By default, Gcal runs in the "hybrid" calendar mode, i.e. Gcal
     automatically changes from the Julian calendar system to the
     Gregorian calendar system if output is related to dates after the
     Gregorian Reformation has happened.  *Note Aspects in
     Internationalization: Internationalization, for more details.
     Actually, four fixed default periods are supported, and that of
     the year 1582, of the year 1700, of the year 1752 and of the year
     1753.

     If Gcal is called with the `--gregorian-reform=1582' option, it
     assumes the Gregorian Reformation has occurred from 5th till 14th
     October 1582.

     If Gcal is called with the `--gregorian-reform=1700' option, it
     assumes the Gregorian Reformation has occurred from 19th till 28th
     February 1700.

     If Gcal is called with the `--gregorian-reform=1752' option, it
     assumes the Gregorian Reformation has occurred from 3rd till 13th
     September 1752.

     If Gcal is called with the `--gregorian-reform=1753' option, it
     assumes the Gregorian Reformation has occurred from 18th till 28th
     February 1753.

     In case another period shall be respected, it can be arranged by
     the option ARGUMENT like `YYYYY,MM,FIRST-DAY,LAST-DAY'.  If the
     Gregorian Reformation has occurred for example on the 7th till the
     17th April 1802, this can be arranged as follows:

          --gregorian-reform=1802,4,7,17

     Gcal is able to represent so-called "proleptic" calendars of a
     definite calendar system.  This means, Gcal only uses a definite
     calendar system during a definite period, although there was a
     change to another calendar system in the historic reality during
     this definite period.  The following proleptic calendar systems
     are actually supported by Gcal:

        * Proleptic Gregorian calendars can be created from AD 302 until
          AD 9999 if `--gregorian-reform=301,12,31,31' is used.
          Unfortunately, Gcal actually cannot represent years before AD
          302 in a proleptic-Gregorian manner.

        * Proleptic Julian calendars can be created from AD 1 until AD
          9999 if `--gregorian-reform=10002,12,31,31' is used.  In this
          case, the actual system date that is normally based on the
          Gregorian calendar and that is used by Gcal, is internally
          and automatically converted into the according Julian date(4)
          (*note Calendar options-Footnote-4::).  The same happens if
          the actual system date is modified by using the actual date
          modifier `%DATE'.  In such a case, Gcal also assumes that the
          given date is a Gregorian date, and converts it automatically
          into the according Julian date internally.  *Note Actual date
          modifier::, for further details.

     Please note that it is possible to corrupt the calendars likewise
     the fixed date feature logically (which works correctly now for
     the year in which the Gregorian Reformation has occurred) if the
     argument of the `--gregorian-reform' option is not used with care.