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Re: Time convertion [message #24248 is a reply to message #24126]

Tue, 20 March 2001 06:04

Alex Schuster
Messages: 124
Registered: February 1997

Senior Member

JD Smith wrote:

> Alex Schuster wrote:

>> I found such a thing in the Astro library, st2date, input is the
>> seconds-since-1970, output is year, month, day etc., and even day and
>> month in ASCII notation if one likes. Great. But I did not find
>> something yet to convert to seconds-since-1970. I could write it myself,
>> but I guess this already had be done some dozen times. Some big routine
>> with many, many keywords to convert between all those formats would be
>> nice :)
>
> Hmm... I doubt you found that in the Astro library, since I wrote it and
> posted it to the newsgroup back in 1998. I did use daycnv from the
> astro package to convert julian to calendar dates.

Umm, right. I found it in the folder where my copy of the Astro library
resides.

> The recent
> IDL-bundled "caldat" will work just as well for that now.

Hooray! I hope it also can output various time strings... but I'm still
using IDL 5.2 :(

> In any case,
> it is oh so trivial to convert date to systime, the inverse:
>
> st=(julday(month,day,year,hr,min,sec)-2440587.5D)*86400.0D

Okay, right. Once you know that these Julian Days are, and if you don't
think about leap seconds. I already did the same, but made the mistake
of using julday(1,1,1970) instead of julday(1,1,1970,0,0,0), which gives
half a day offset. Okay, my fault, but if IDL already had such a
conversion routine, I wouldn't have to think about it, and I wouldn't be
able to make such mistakes.
Another example, why can't systime() just also output julian days, give
it one more keyword and that's it.

Reimar's link was a good tip and made things easier:
http://fermi.jhuapl.edu/s1r/idl/s1rlib/time/time.html
Many many routines converting various time and/or date strings to other
formats (of course no direct conversion to secs-since-1970).

--
Alex Schuster Wonko@weird.cologne.de PGP Key available
alex@pet.mpin-koeln.mpg.de

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[Message index]

		Re: Time convertion By: Pavel A. Romashkin on Wed, 14 March 2001 10:57
		Re: Time convertion By: John-David T. Smith on Wed, 14 March 2001 10:50
		Re: Time convertion By: Liam E. Gumley on Wed, 14 March 2001 10:17
		Re: Time convertion By: davidf on Wed, 14 March 2001 09:44
		Re: Time convertion By: Pavel A. Romashkin on Wed, 14 March 2001 09:09
		Re: Time convertion By: Alex Schuster on Tue, 20 March 2001 06:03
		Re: Time convertion By: R.Bauer on Mon, 19 March 2001 13:12
		Re: Time convertion By: tam on Wed, 14 March 2001 11:52
		Re: Time convertion By: Wayne Landsman on Wed, 14 March 2001 11:30
		Re: Time convertion By: Alex Schuster on Tue, 20 March 2001 06:04

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