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Re: Time Woes [message #30570 is a reply to message #30471]

Wed, 01 May 2002 13:10

Ken Mankoff
Messages: 158
Registered: February 2000

Senior Member

On Wed, 1 May 2002, David Fanning wrote:
> I have a time array that purports to be the number of seconds from 1
> Jan 1980. How in the world do I convert that to something I can use
> with routines I have access to?

First, before you deal with any conversions, you have to understand
exactly what it means to have "seconds since 1980".

What clock system are you on? Is it 365 day years (and leap-years), or
365.25, or something more accurate than that? The clocks here at work
have leap-seconds thrown in every few months (I believe this is one of
the many subtle distinctions between UTC, GMT, and Zulu, but am not
sure).

Then again, depending on the resolution of the data (and x-axis if you
are plotting it), does any of these different "times" matter to you?

Beyond that, I am not sure what you want to convert it to... Can't you
just start doing division until you have it into "days since 1980"?

The other option is to add 10 years worth of seconds onto the array
(again: exactly how many seconds are there in your year calendar?),
now you have it as seconds from 1 Jan 1970. This is the same format as
UNIX and the IDL SYSTIME() function, so you should be able to handle
this array better...

Does this help?

-k.
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http://lasp.colorado.edu/mars/
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[Message index]

		Time Woes By: David Fanning on Wed, 01 May 2002 12:41
		Re: Time Woes By: Craig Markwardt on Thu, 02 May 2002 15:26
		Re: Time Woes By: thompson on Thu, 02 May 2002 14:51
		Re: Time Woes By: btupper on Thu, 09 May 2002 07:21
		CDF_EPOCH (was Re: Time Woes) By: Brian Jackel on Thu, 02 May 2002 12:05
		Re: Time Woes By: Struan Gray on Thu, 02 May 2002 08:34
		Re: Time Woes By: David Fanning on Thu, 02 May 2002 06:38
		Re: Time Woes By: btupper on Thu, 02 May 2002 06:11
		Re: Time Woes By: Ken Mankoff on Thu, 02 May 2002 06:07
		Re: Time Woes By: Paul Van Delst[1] on Wed, 01 May 2002 14:24
		Re: Time Woes By: David Fanning on Wed, 01 May 2002 14:00
		Re: Time Woes By: Robert Stockwell on Mon, 06 May 2002 06:14
		Re: Time Woes By: Ken Mankoff on Wed, 01 May 2002 13:10

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