JUL() Function - Get Julian Date
Syntax
JUL(year,month,day{,ERR=lineref})
Description
For BBj-specific information, see JUL() Function - BBj.
The JUL() function returns the Julian day number for a given date.
|
Parameter |
Description |
|---|---|
|
year |
Calendar year such as 1999 or a small number such as 99 that is interpreted to indicate 1999. Note that 00 as the year number is 1900, not 2000. |
|
month |
Month of the year, as represented by an integer. January =1, February=2, etc. A zero may only be used to retrieve the Julian value for the current date, as seen below. |
|
day |
Day of the month. |
|
ERR=lineref |
Branch to be taken if an error occurs during execution. |
To return the Julian value for the current date, enter the following:
JUL(0,0,0)
A Julian date is defined as the number of days since January 1, 4713
BC. Because the days are sequentially numbered it is a convenient way
to determine the number of days between any two dates. By definition,
a Julian date changes at noon. PRO/5, however, changes at midnight.
The PRO/5 JUL() function works for any date from the 1800s to the year
4000 (past the end of the Julian cycle). The main problem with early Julian
dates is caused by leap years. For centuries, every fourth year was considered
a leap year. Advances in the knowledge of astronomy led to the current
definition of a leap year, however, and the calendar "slipped"
by a two weeks. To allow the calendar to "catch up", approximately
two weeks had to be skipped. This correction was performed at different
times by different countries in the 16th to 18th centuries. PRO/5 considers
these early dates unimportant and assumes the early calendars to be correct.
Any date after the year 1752 is now standard on any calendar.
NOTE: Some popular worksheets erroneously
consider 1900 to be a leap year. This could require special attention
when exchanging data with PRO/5.