| T O P I C R E V I E W |
| newuser_ca |
Posted - 07/26/2012 : 2:15:55 PM
OriginPro 8.6 in Win7
I have a dataset contains Julian Day value as "Date" column. But when I import and convert the date, I have 12-hour offset in Origin.
I noticed that the Julian Day value in Origin is not the same as I got from wiki.
Example: Julian Day Value = 2456135
I use the following codes in Origin to conver to string:
double jd = 2456135;
out_str(get_date_str(jd, LDF_SHORT_AND_HHMM_SEPARCOLON));
The result I got in Origin is: "7/27/2012 00:00"
I used some converters in the Internet, I got "2012 July 26 12:00:00". There is a 12-hour difference.
I searched in the Internet. The Julian Day in wiki is 12h Jan 1, 4713 BC (http://en.wikipedia.org/wiki/Julian_day)
It seems to me that the Julian Day value in Origin counts from 0h instead of 12h.
Is this a bug in Origin or is it set as this way?
Thanks. |
| 4 L A T E S T R E P L I E S (Newest First) |
| newuser_ca |
Posted - 08/02/2012 : 3:54:51 PM
Thanks for the explanation.
That is clear now. |
| greg |
Posted - 08/01/2012 : 11:09:54 AM
All our help files clearly state the relation between Origin's Julian Day numbers and the standard Astronomical Julian Day value:
http://www.originlab.com/www/helponline/Origin/en/UserGuide/Dates_and_Times_in_Origin.html
http://www.originlab.com/www/support/resultstech.aspx?ID=295&language=English&Version=7.5
http://wiki.originlab.com/~originla/howto/index.php?title=QuickHelp:What_is_the_difference_between_the_underlying_mathematical_system
In fact, other non-astronomical software similarly start their days at midnight whether they use the Julian base as Origin does or one of Excels two date systems or Posix (Unix) time. |
| newuser_ca |
Posted - 07/27/2012 : 09:40:30 AM
But this is not the definition of Julian Day.
Julian Day is defined as "12h Jan 1, 4713 BC".
Anyway, I will convert it by myself. |
| Penn |
Posted - 07/27/2012 : 01:54:57 AM
Hi,
Actually, Origin uses a 12 hour offset in order to have 0 hours coincide with midnight. So, the result should be correct.
Penn |
