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Re: What about my last date functions? there are some error?

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From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: What about my last date functions? there are some error?
Date Tue, 08 Nov 2016 12:11:58 -0800
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jadill33@gmail.com writes:
[...]
> I'm curious, if you don't mind, what's your use-case on calculating a
> Julian date when the Gregorian calendar is primarily what we use these
> days?

Confusingly, the word "Julian" is used for two different purposes
in calendar discussions.

The Julian calendar was the one that was replaced by the Gregorian
calendar starting in 1582.  The Julian calendar has a leap year
every 4 years.  The Gregorian calendar uses a formula that gives
us 97 leap years in every 400 years, which is a much better (but
still imperfect) approximation to reality.

A Julian Day Number (JDN) is the whole number of days since noon,
Jan 1, 4713 BCE.  A Julian date is the same thing, but with an added
fractional part.  They're commonly used in astronomy, because they
make calculations simpler (no leap years, no variable number of
days per month).  It plays a similar role to the Unix epoch time,
the number of seconds since 1970-01-01 00:00:00 UTC, a representation
optimized for ease of calculation rather than for human readability.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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Thread

What about my last date functions? there are some error? Rosario19 <Ros@invalid.invalid> - 2016-11-08 11:28 +0100
  Re: What about my last date functions? there are some error? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-11-08 10:55 +0000
    Re: What about my last date functions? there are some error? "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2016-11-08 19:00 +0800
    Re: What about my last date functions? there are some error? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-11-08 11:04 +0000
      Re: What about my last date functions? there are some error? "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2016-11-08 19:22 +0800
    Re: What about my last date functions? there are some error? Richard Heathfield <rjh@cpax.org.uk> - 2016-11-08 11:35 +0000
      Re: What about my last date functions? there are some error? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-11-08 15:46 +0000
        Re: What about my last date functions? there are some error? Richard Heathfield <rjh@cpax.org.uk> - 2016-11-08 16:20 +0000
          Re: What about my last date functions? there are some error? Rosario19 <Ros@invalid.invalid> - 2016-11-08 17:44 +0100
            Re: What about my last date functions? there are some error? Richard Heathfield <rjh@cpax.org.uk> - 2016-11-08 16:51 +0000
              Re: What about my last date functions? there are some error? Jerry Stuckle <jstucklex@attglobal.net> - 2016-11-08 13:21 -0500
          Re: What about my last date functions? there are some error? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-11-08 18:06 +0000
            Re: What about my last date functions? there are some error? Richard Heathfield <rjh@cpax.org.uk> - 2016-11-08 18:56 +0000
              Re: What about my last date functions? there are some error? Keith Thompson <kst-u@mib.org> - 2016-11-08 12:05 -0800
              Re: What about my last date functions? there are some error? David Brown <david.brown@hesbynett.no> - 2016-11-08 21:10 +0100
                Re: What about my last date functions? there are some error? Richard Heathfield <rjh@cpax.org.uk> - 2016-11-08 20:16 +0000
          Re: What about my last date functions? there are some error? jadill33@gmail.com - 2016-11-08 11:16 -0800
            Re: What about my last date functions? there are some error? Richard Heathfield <rjh@cpax.org.uk> - 2016-11-08 20:08 +0000
            Re: What about my last date functions? there are some error? Keith Thompson <kst-u@mib.org> - 2016-11-08 12:11 -0800
              Re: What about my last date functions? there are some error? Keith Thompson <kst-u@mib.org> - 2016-11-08 12:29 -0800
      Re: What about my last date functions? there are some error? Rosario19 <Ros@invalid.invalid> - 2016-11-08 17:41 +0100
        Re: What about my last date functions? there are some error? asetofsymbols@gmail.com - 2016-11-08 11:26 -0800
          Re: What about my last date functions? there are some error? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-11-08 19:38 +0000
  Re: What about my last date functions? there are some error? Keith Thompson <kst-u@mib.org> - 2016-11-08 08:19 -0800

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