JDay and J2D
------------

This archive contains RISC OS versions of the Julian Date program.

This is a simple command to convert calendar dates to julian dates. Quite 
useful in timing situations where you need elapsed time between dates. Also 
useful for astronomy applications.

The date system in use follows these rules: 
   1. Julian calendar dates before October 1582
   2. Gregorian calendar dates after October 1582
   3. 04 October 1582 Julian (JD 2299160) is followed by 15 October 1582 
      Gregorian (JD 2299161)
   4. Julian calendar means leap years every four years, no exceptions
   5. Gregorian calendar means leap years every four years except years not
      divisible by 400
   6. There is a year 0 between years -1 and 1
   7. The earliest usable date is -4712/01/01 12:00:00 (JD 0)
   8. The maximum usable date is 5874773/08/15 23:59:59
      (JD 2147438064.499988 )

There are two binarys: JDay and J2D:

* JDay
  This program will, if no arguments are given, display the current time as
  Julian time. If, however, the program is supplied with a date such as
  
  jday -d 0/01/01 12:00:00
  
  ...it will display the julian time for that date.
  
* J2D
  This program will convert and print the Gregorian (e.g. 2000/08/18 05:25:
  27) time from a given Julian time (e.g. 2440587.500000)
  
  
These program are copyright Hiram Clawson. The RISC OS post was undertaken by
I, Richard Butler (richardjcbutler@eircom.net). I hope to release RISC OS
version of any further versions if and when they become available.

The SourceForge page for this project is: 
   http://sourceforge.net/projects/jday
   
   
   
 