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[Emacs-diffs] Changes to emacs/man/calc.texi,v
From: |
Jay Belanger |
Subject: |
[Emacs-diffs] Changes to emacs/man/calc.texi,v |
Date: |
Mon, 19 Mar 2007 03:36:18 +0000 |
CVSROOT: /cvsroot/emacs
Module name: emacs
Changes by: Jay Belanger <jpb> 07/03/19 03:36:17
Index: calc.texi
===================================================================
RCS file: /cvsroot/emacs/emacs/man/calc.texi,v
retrieving revision 1.90
retrieving revision 1.91
diff -u -b -r1.90 -r1.91
--- calc.texi 17 Mar 2007 18:35:08 -0000 1.90
+++ calc.texi 19 Mar 2007 03:36:17 -0000 1.91
@@ -17379,9 +17379,10 @@
to exactly 30 days even though there is a daylight-saving
transition in between. This is also true for Julian pure dates:
@samp{julian(<may 1 1991>) - julian(<apr 1 1991>)}. But Julian
-and Unix date/times will adjust for daylight saving time:
+and Unix date/times will adjust for daylight saving time: using Calc's
+default daylight saving time rule (see the explanation below),
@samp{julian(<12am may 1 1991>) - julian(<12am apr 1 1991>)}
-evaluates to @samp{29.95834} (that's 29 days and 23 hours)
+evaluates to @samp{29.95833} (that's 29 days and 23 hours)
because one hour was lost when daylight saving commenced on
April 7, 1991.
@@ -17501,12 +17502,15 @@
@vindex math-daylight-savings-hook
@findex math-std-daylight-savings
By default Calc always considers daylight saving time to begin at
-2 a.m.@: on the second Sunday of March, and to end at 2 a.m.@: on the
-first Sunday of November. This is the rule that has been in effect
-in North America since 2007. If you are in a country that uses
-different rules for computing daylight saving time, you have two
-choices: Write your own daylight saving hook, or control time
-zones explicitly by setting the @code{TimeZone} variable and/or
+2 a.m.@: on the second Sunday of March (for years from 2007 on) or on
+the last Sunday in April (for years before 2007), and to end at 2 a.m.@:
+on the first Sunday of November. (for years from 2007 on) or the last
+Sunday in October (for years before 2007). These are the rules that have
+been in effect in much of North America since 1966 and takes into
+account the rule change that began in 2007. If you are in a
+country that uses different rules for computing daylight saving time,
+you have two choices: Write your own daylight saving hook, or control
+time zones explicitly by setting the @code{TimeZone} variable and/or
always giving a time-zone argument for the conversion functions.
The Lisp variable @code{math-daylight-savings-hook} holds the