From: Zefram <zefram@fysh.org>
To: 21902@debbugs.gnu.org, guile-devel@gnu.org
Subject: Re: bug#21902: doc incorrectly describes Julian Date
Date: Fri, 24 Jun 2016 19:01:43 +0100 [thread overview]
Message-ID: <20160624180143.GI1170@fysh.org> (raw)
In-Reply-To: <87eg7mcxgb.fsf@pobox.com>
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Andy Wingo wrote:
>Would you like to propose a specific patch to the documentation?
Sure. Patch attached.
-zefram
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--- a/doc/ref/srfi-modules.texi 2014-03-20 20:21:21.000000000 +0000
+++ b/doc/ref/srfi-modules.texi 2016-06-24 18:57:59.088243245 +0100
@@ -2461,8 +2461,8 @@
@cindex UTC
@cindex TAI
This module implements time and date representations and calculations,
-in various time systems, including universal time (UTC) and atomic
-time (TAI).
+in various time systems, including Coordinated Universal Time (UTC)
+and International Atomic Time (TAI).
For those not familiar with these time systems, TAI is based on a
fixed length second derived from oscillations of certain atoms. UTC
@@ -2494,18 +2494,12 @@
@cindex julian day
@cindex modified julian day
Also, for those not familiar with the terminology, a @dfn{Julian Day}
-is a real number which is a count of days and fraction of a day, in
-UTC, starting from -4713-01-01T12:00:00Z, ie.@: midday Monday 1 Jan
-4713 B.C. A @dfn{Modified Julian Day} is the same, but starting from
-1858-11-17T00:00:00Z, ie.@: midnight 17 November 1858 UTC. That time
-is julian day 2400000.5.
-
-@c The SRFI-1 spec says -4714-11-24T12:00:00Z (November 24, -4714 at
-@c noon, UTC), but this is incorrect. It looks like it might have
-@c arisen from the code incorrectly treating years a multiple of 100
-@c but not 400 prior to 1582 as non-leap years, where instead the Julian
-@c calendar should be used so all multiples of 4 before 1582 are leap
-@c years.
+is a real number which is a count of days and fraction of a day, in UT,
+starting from -4713-11-24T12:00:00Z, ie.@: midday UT on Monday 24 November
+4714 BC in the proleptic Gregorian calendar (1 January 4713 BC in the
+proleptic Julian calendar). A @dfn{Modified Julian Day} is the same,
+but starting from 1858-11-17T00:00:00Z, ie.@: midnight UT on Wednesday
+17 November AD 1858. That time is julian day 2400000.5.
@node SRFI-19 Time
next prev parent reply other threads:[~2016-06-24 18:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20151113125813.GM13455@fysh.org>
2016-06-24 17:23 ` bug#21902: doc incorrectly describes Julian Date Andy Wingo
2016-06-24 18:01 ` Zefram [this message]
2016-06-25 9:36 ` reviewer for time-related bugs (srfi-19) Andy Wingo
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