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MathGroup Archive 1996

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Re: Julian Day Calculation - Plea for Help

  • To: mathgroup at smc.vnet.net
  • Subject: [mg3967] Re: Julian Day Calculation - Plea for Help
  • From: ianc (Ian Collier)
  • Date: Mon, 13 May 1996 01:47:05 -0400
  • Organization: Wolfram Research, Inc.
  • Sender: owner-wri-mathgroup at wolfram.com

In article <searchme-2904961319480001 at 204.250.36.184>,
searchme at earthlink.net (Matthew K.) wrote:

> Hi,
> 
> Please forgive me if this is a duplicate posting - I tried posting
> yesterday and while it appeared to post, I was having a great deal of
> trouble with my server and it now appears that this did not post at all. 
> <sigh>  Sorry for any inconvenience if it *does* appear mysteriously
> tomorrow.
> 
> I need , if possible, to get the equation for calculating the Julian Day
> well into the future (we're talking 1000 years here).  I have been unable
> to come up with an equation on the Web (limited at least in part by my
> wonderful but antique Mac Plus <grin>).
> 
> If anyone can help me, it would be most appreciated.  Please e-mail if you
> would at searchme at earthlink.net as I seldom check this group, not being a
> professional in this field.  And if it is not something that can be easily
> calculated (requires an algorithm or something along those lines), could
> someone please let me know that??  Thanks so much for any assistance.
> 
> Lisa
> -- 
> emergency address only:  SMS CDs @aol.com


These conversions can be done using Mathematica's CalendarChange 
function, which is defined in Miscellaneous`Calendars`, one of 
the standard packages distributed with Mathematica. if you want 
to see how it is implemented yopu can simply open the package with 
a text editor and examine the Mathematica code.

Here is an example (using a date 1000 years in the future):

In[4]:=
    Needs[ "Miscellaneous`Calendar`" ]

In[5]:=
    ?CalendarChange

    CalendarChange[date, calendar1, calendar2] converts a date
       in calendar1 to a date in calendar2.

In[6]:=
    CalendarChange[ {2996, 5, 6}, Gregorian, Julian ]
Out[6]=
    {2996, 4, 16}

I hope this helps.

--Ian

-----------------------------------------------------------
Ian Collier
Wolfram Research, Inc.
-----------------------------------------------------------
tel:(217) 398-0700   fax:(217) 398-0747    ianc at wolfram.com
Wolfram Research Home Page:         http://www.wolfram.com/
-----------------------------------------------------------

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