Computed negative CLOCK time 1 hour off

Computed negative CLOCK time 1 hour off

[Chris Leyon]

When Org automatically computes a time interval which is negative, it
is off by 1 hour.  (This may or may not be related to Chris Willard's
"1 hour earlier" problem.)  Positive time intervals seem okay.   I'm
using 6.08c on GNU Emacs 22.1.

To reproduce: emacs -Q

Start with this line:
CLOCK: [2008-10-16 Thu 10:00]--[2008-10-16 Thu 10:00] =>  0:00

Position point over the "00" in the second timestamp.  Press S-down.  See
CLOCK: [2008-10-16 Thu 10:00]--[2008-10-16 Thu 09:55] => -1:55

Re: Computed negative CLOCK time 1 hour off

[Carsten Dominik]

Hi Chris,

what could possibly be the purpose of a negative time range?  Are you  
working for a secret government agency?

:-)

- Carsten

On Oct 16, 2008, at 5:24 PM, Chris Leyon wrote:

> When Org automatically computes a time interval which is negative, it
> is off by 1 hour.  (This may or may not be related to Chris Willard's
> "1 hour earlier" problem.)  Positive time intervals seem okay.   I'm
> using 6.08c on GNU Emacs 22.1.
>
> To reproduce: emacs -Q
>
> Start with this line:
> CLOCK: [2008-10-16 Thu 10:00]--[2008-10-16 Thu 10:00] =>  0:00
>
> Position point over the "00" in the second timestamp.  Press S- 
> down.  See
> CLOCK: [2008-10-16 Thu 10:00]--[2008-10-16 Thu 09:55] => -1:55
>
>
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> Remember: use `Reply All' to send replies to the list.
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Re: Computed negative CLOCK time 1 hour off

[Chris Leyon]

[-- Attachment #1: Type: text/plain, Size: 701 bytes --]

There is a precedent in the Emacs manual -- Appendix E, Antinews: "For
those users who live backwards in time [...]"

:-)

I admit there may not be great practical utility in a negative time
range.  But the interval is well-defined so it ought to be computed
correctly.  I would say that a wrong answer is worse than no answer
since it may be believed correct at first glance, when it is not.

Anyway, I'm including a patch for 6.09 which seems to fix the problem....

On Thu, Oct 16, 2008 at 12:39 PM, Carsten Dominik
<dominik@science.uva.nl> wrote:
> Hi Chris,
>
> what could possibly be the purpose of a negative time range?  Are you
> working for a secret government agency?
>
> :-)
>
> - Carsten

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: neg-time.patch --]
[-- Type: text/x-patch; name=neg-time.patch, Size: 635 bytes --]

--- /home/cleyon/u/share/emacs/site-lisp/org-6.09/lisp/org.el	2008-10-09 10:25:12.000000000 -0400
+++ org.el	2008-10-16 21:57:45.000000000 -0400
@@ -2511,11 +2511,12 @@
 		      (apply 'encode-time (org-parse-time-string te)))
 		     (time-to-seconds
 		      (apply 'encode-time (org-parse-time-string ts))))
-		h (floor (/ s 3600))
+		sign (if (< s 0) "-" "")
+		h (truncate (/ s 3600))
 		s (- s (* 3600 h))
-		m (floor (/ s 60))
+		m (truncate (/ s 60))
 		s (- s (* 60 s)))
-	  (insert " => " (format "%2d:%02d" h m))
+	  (insert " => " (format "%s%d:%02d" sign (abs h) (abs m)))
 	  t))))))
 
 (defun org-check-running-clock ()

[-- Attachment #3: Type: text/plain, Size: 204 bytes --]

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Re: Computed negative CLOCK time 1 hour off

[Carsten Dominik]

Hi Chris
On Oct 17, 2008, at 4:03 AM, Chris Leyon wrote:

> There is a precedent in the Emacs manual -- Appendix E, Antinews: "For
> those users who live backwards in time [...]"

Great answer.  And thanks for the patch.  I am applying it.
However,  I am sure there are more similar problems, so
I am not at all sure that calculating clock sums, or summing
properties that contain times, will work properly with negative
time intervals.  I did not pay any attention to this when writing
those functions, and it is likely that similar problems will exist.

- Carsten


>
>
> :-)
>
> I admit there may not be great practical utility in a negative time
> range.  But the interval is well-defined so it ought to be computed
> correctly.  I would say that a wrong answer is worse than no answer
> since it may be believed correct at first glance, when it is not.
>
> Anyway, I'm including a patch for 6.09 which seems to fix the  
> problem....
>
> On Thu, Oct 16, 2008 at 12:39 PM, Carsten Dominik
> <dominik@science.uva.nl> wrote:
>> Hi Chris,
>>
>> what could possibly be the purpose of a negative time range?  Are you
>> working for a secret government agency?
>>
>> :-)
>>
>> - Carsten
> <neg-time.patch>_______________________________________________
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