What is the precise definition of JDE's Julian Date format?

Question

I am writing code to convert from a Gregorian date to a JDE (J.D.Edwards) Julian date.

Note: a JDE Julian date is different from the normal usage of the term Julian date.

As far as I can work out from Googling, the definition of a JDE Julian date is:

1000*(year-1900) + dayofyear

where year is the 4-digit year (e.g. 2009), and dayofyear is 1 for 1st January, and counts up all year to either 365 or 366 for 31st December (depending whether this is a leap year).

My question is this: are years before 1900 supported? If so, does the above formula still hold, or should it be this:

1000*(year-1900) - dayofyear

(note minus instead of plus.)

or something else?

Does anyone have a link to the official documentation for this date format?

Hautevienne

And they called that 'Julian' ? Silly and unhelpful. – Rummer

Yes, I completely agree! – Hautevienne

Please state in the question what JDE is. E.g. is it the Java Development Environment, an Emacs Lisp package ? – Hauge

We could all use a break here in the name of these things. How about an abbreviation to JS for Joseph Justus Scaliger or even JJS. en.wikipedia.org/wiki/Joseph_Justus_Scaliger. So what language is that? – Potentiality

Answer 1

The JDE Julian date consists of CYYDDD which is Century, Year, Day of year.

Century is zero for 20th e.g. 19XX and one for 21st e.g. 20XX.

The year is two digits. So 101001 is 1 January 2001

As you can see this will not support dates before 1900.

See this Oracle page for a simple and official explanation: About the Julian Date Format

Sabo

If you look on the tools documentation on Oracle Metalink you will find it there (e.g. tools foundation guide for your JDE release) if you have access to that. But personally I have been working on JDE for over ten years and use this date format many times each day, I know it intimately :-) – Sabo

Answer 2

The "JDE Julian Date Converter" does return a negative value for:

1809/07/23 : -90635

As opposed to the classical Julian Date:

The Julian date for CE  1809 July 23 00:00:00.0 UT is
JD 2381986.50000

Here is a example of JD EDWARDS (AS/400 software) Julian Date, but that is not an "official" documentation and it does not seems to support dates before 1900...

Note: this "ACC: How to Convert Julian Days to Dates in Access and Back" does not support date before 1900 either... as it speaks about an "informal" Julian day, commonly used by government agencies and contractors.

The informal Julian day format used in this article is the ordinal day of a year (for example, Julian day 032 represents February 1st, or the 32nd day of the year).
Variations on informal Julian day formats include using a preceding two-digit year (for example 96032 for 2/1/96) and separating the year with a dash (for example 96-032).
Another, less popular, Julian day format uses a one digit year (for example 6-032). These additional formats do not uniquely identify the century or decade. You should carefully consider the consequences when using these formats; for example, the Julian day 00061 can be interpreted as 3/1/2000 or 3/2/1900.

Leilaleilah

Thanks - I did find these links through my Googling, but none of them gave me a definitive answer. Maybe I'm being dense, but I can't guess what formula the macek.cc converter is using to get to this value for 1809-07-23. The two formulae I gave above would give either -90796 or -91204. – Hautevienne

Answer 3

Update: Sorry, JDE is probably something else. But for reference:

The JDE I know is different. From page 59 in the book "Astronomical algorithms" (Jean Meeus, ISBN 0-943396-35-2):

"If the JD corresponds to an instant measured in the scale of Dynamical Time (or Ephemeris Time), the expression Julian Ephemeris Day (JDE) is generally used. (Not JED as
it is sometimes written. The 'E' is a sort of index appended to 'JD')"

JD and JDE (for the same point in time) are close in value as the difference UT and ET is on the order of minutes. E.g. ET-UT was 56.86 seconds in 1990 and -2.72 seconds in 1900.

There is also MJD (Modified Julian Day):

MJD = JD - 2400000.5

Zero point for MJD is 1858-11-17, 0h UT.

---

Note that JD as Julian date is a misnomer. It is Julian day. The JD has nothing to do with the Julian calendar. (This is in disagreement with the Wikipedia article, this is from the author of the book mentioned above, Jean Meeus - a Belgian astronomer specializing in celestial mechanics.)

Hauge

Answer 4

Maybe off from the question, you can convert in Excel using the following formula:

Convert Julian to Date in Excel

In Cell A2 place a Julian date, like 102324
in Cell B2 place this formula: (copy it in)
=DATE(YEAR("01/01/"&TEXT(1900+INT(A2/1000),0)),MONTH("01/01/"&TEXT(1900+INT(A2/1000),0)),DAY("01/01/"&TEXT(1900+INT(A2/1000),0)))+MOD(A2,1000)-1

The date 11/20/02 date will appear in cell B2

Convert Date to Julian in Excel

In Cell C2 copy this formula:
=(YEAR(B2)-2000+100)*1000+B2-DATE(YEAR(B2),"01","01")+1

This will convert B2 back to 102324

Arlyn

Answer 5

Save the below source code in a source member called JDEDATES. Use the runsqlstm on the first line to create the functions. You can then do things like

select  jde2date(A1UPMJ), f.* from f00095 f                            

and see a real date.

Source:

--RUNSQLSTM SRCFILE(qtxtsrc) SRCMBR(JDEDATES) COMMIT(*NONE)  NAMING(*SQL) 
 -- jde 2 date                                                                    

 create function QGPL/jde2date ( d decimal(7,0))                                  
 returns date                                                                     
 language sql                                                                     
 deterministic                                                                    
 contains sql                                                                     
    SET OPTION DATFMT=*ISO                                                        
 BEGIN                                                                            
  if d=0 then return null;                                                        
  else                                                                            
       return date(digits(decimal(d+1900000,7,0)));                               
  end if;                                                                         
 end;                                                                            -- date 2 jde                                     
 create function QGPL/date2jde ( d date)           
 returns decimal(7,0)                              
 language sql                                      
 deterministic                                     
 contains sql                                      
    SET OPTION DATFMT=*ISO                         
 BEGIN                                             
  if d is null then return 0;                      
  else                                             
  return (YEAR(D)-1900)*1000+DAYOFYEAR(D);         
  end if;                                          
 end ;                                              

Glycine

Answer 6

Several years late to the party, but for other folks like me that find yourselves working with legacy systems like this, I hope some of my java snippets can help. I'm leveraging the fact that you can convert this CYYDDD format into yyyyDDD format and parse based on that.

    import java.util.Date;
    import java.util.GregorianCalendar;
    import java.util.Calendar;
    import java.util.SimpleDateFormat;
    
    String jdeJulianDate = "099365"; //Testing with December 31, 1999
    
    // Compile what the year number is
    int centIndex = Integer.parseInt(jdeJulianDate.substring(0,1));
    int yearIndex = Integer.parseInt(jdeJulianDate.substring(1,3));
    int yearNumber = 1900 + (100 * centIndex) + yearIndex;
    
    // Put the year number together with date ordinal to get yyyyDDD format
    String fullDate = String.valueOf(yearNumber) + jdeJulianDate.substring(3,6);
    
    // Date parsing, so need to wrap in try/catch block
    try {
        Date dt = new SimpleDateFormat("yyyyDDD").parse(fullDate);
        // Validate it parses to a date in the same year...
        Calendar cal = new GregorianCalendar();
        cal.setTime(dt);
        if (cal.get(Calendar.YEAR) != yearNumber) {
            // Cases happen where things like 121366 (should be invalid) get parsed, yielding 2022-01-01.
            // Throw exception or what-not here.
        }
    }
    catch (Exception e) {
        // Date parsing error handling here
    }

Waverley

Answer 7

A sample of VBA code to convert back and forth between JDE Julian Date and Gregorian:

Public Const Epoch = 1900
Public Const JDateMultiplier = 1000
Public Const FirstJan = "01/01/"

Public Function Julian2Date(ByVal vDate As Long) As Date

    Dim Year As Long
    Dim Days As Long
    Dim SeedDate As Date

    '   Day Number
    Days = vDate - (Int(vDate / JDateMultiplier) * JDateMultiplier) - 1
    '   Calendar Year
    Year = ((vDate - Days) / JDateMultiplier) + Epoch
    '   First Day of Calendar Year
    SeedDate = CDate(FirstJan + CStr(Year))

    '   Add Number of Days to First Day in Calendar Year
    Julian2Date = DateAdd("d", Days, SeedDate)

End Function

Public Function Date2Julian(ByVal vDate As Date) As Long

    Dim JYear As String
    Dim BeginDate As Date
    Dim JDays As Long

    '   Calendar Year
    JYear = Format(Year(vDate), "0000")
    '   First Day of Calendar Year
    BeginDate = CDate(FirstJan + JYear)
    '   Day Number
    JDays = DateDiff("d", BeginDate, vDate) + 1

    '   Add Number of Days to Year Number
    Date2Julian = ((CLng(JYear) - Epoch) * JDateMultiplier) + JDays

End Function

I have tried to make it as clear and simple as possible, and to this end I have intentionally left out any error trapping. However, you should be able to add the code to a VBA module and call them directly from your own code.

I also include some useful snippets of T-SQL:

Todays Date as JDE Julian Date:

 (datepart(yy,getdate())-1900) * 1000 + datepart(dy, getdate())

Convert JDE Julian Date to Gregorian (DD/MM/YYYY), replace XXXXXX with the column name containing the JDE Julian Date:

convert (varchar, dateadd (day,convert (int, right(XXXXXX,3)) - 1, convert (datetime, ('1/1/' + convert ( varchar, (cast(left(right(XXXXXX+1000000,6),3) as varchar) + 1900))))),103)

If you require a different Gregorian format, replace the 103 value (right at the end) with the applicable value found here: https://msdn.microsoft.com/en-us/library/ms187928.aspx

Anchylose

Answer 8

I have an easy way for C using time now and epoch 1970, 01, 01 midnight if anybody is interested. But this is for Julian Day Numbers which is not the same as JDE but they are similar in respect to using math to compute days and I'm sure this idea could be adapted for JDE. Sometimes people just confuse the two like I do. Sorry. But still this is an example of using a time reference which should always be done and since most computers use this it would be just as easy for us not to get too bogged down in dates and just use days before or after this epoch.

Since JDE is now owned by Oracle, they also now support Julian_Day. see: https://docs.oracle.com/javase/8/docs/api/java/time/temporal/JulianFields.html

#include <stdio.h>
#include <time.h>
#define EPOCH (double)  2440587.5 /* Julian Day number for Jan. 01, 1970 midnight */
int main ()
{
 double days = time(0)/86400.0;

 printf ("%f days since January 1, 1970\n", days);

 printf ("%f\n", days + EPOCH);

 return 0;  
}

Potentiality

Answer 9

Wow, there's a lot of complicated code in some of these answers just to convert to and from JDE julian dates. There are simple ways in Excel and VBA to get there.

FROM JULIAN

Excel (assuming julian date is in A1):

=DATE(1900+LEFT(A1,LEN(A1)-3),1,RIGHT(A1,3))

VBA (from julian date, j, stored as String):

d = DateSerial(1900 + Left$(j, Len(j) - 3), 1, Right$(j, 3))

VBA (from julian date, j, stored as Long):

d = DateSerial(1900 + Left$(j, Len(CStr(j)) - 3), 1, Right$(j, 3))

TO JULIAN

Excel (assuming date is in A1):

=(YEAR(A1)-1900)*1000+A1-DATE(YEAR(A1),1,0)

VBA (to a Long, j):

j = (Year(d) - 1900) * 1000 + DatePart("y", d)

Coextensive