On April 17, Robert Dodier wrote:
-----------------
I guess you have Maxima built with GCL on Windows.
GCL has a global variable SI::*DEFAULT-TIME-ZONE* which by
default is -1. You can set this to some other value, e.g.
:lisp (setq si::*default-time-zone* 7)
now I get timedate() => 2010-04-17 08:51:46-07:00
Digging around in the GCL source code, I see that the time
zone is retrieved by, I guess, a Mingw function named
GetTimeZoneInformation. I don;t know if the -1 value is a bug
in that function or in GCL or what.
Hope this helps,
-----------------------------
On April 17 Leo Butler wrote:
--------------
Ted, timedate can be patched to give you the functionality
you want. The patched code replicates timedate() while
timedate(+8) will give you the offset time.
Leo
(defmvar $time_zone_offset nil
"The offset of the local time zone from GMT. This offset does
not account for daylight savings.")
(defun $timedate (&optional (tz-offset $time_zone_offset))
(multiple-value-bind
(second minute hour date month year day-of-week dst-p tz)
(decode-universal-time (get-universal-time) tz-offset)
(declare (ignore day-of-week))
(let
((tz-offset (if dst-p (- 1 tz) (- tz))))
(multiple-value-bind
(tz-hours tz-hour-fraction)
(floor tz-offset)
(let
((tz-sign (if (< 0 tz-hours) #\+ #\-)))
(format nil "~4,'0d-~2,'0d-~2,'0d
~2,'0d:~2,'0d:~2,'0d~a~2,'0d:~2,'0d"
year month date hour minute second tz-sign (abs tz-hours)
(floor (* 60 tz-hour-fraction))))))))
-------------------------------------------
Thanks to you both for solutions to my query.
Both solutions do the job, although the lisp
patch did not behave as expected with no
argument:
-------------------------
(%i1) timedate();
(%o1) 2010-04-18 19:51:22+01:00
(%i2) :lisp (setq si::*default-time-zone* 7)
7
(%i2) timedate();
(%o2) 2010-04-18 11:52:20-07:00
(%i3) load("new-timedate.lisp");
(%o3) new-timedate.lisp
(%i4) timedate();
Maxima encountered a Lisp error:
Error in DECODE-UNIVERSAL-TIME [or a callee]: NIL is not of type NUMBER.
Automatically continuing.
To reenable the Lisp debugger set *debugger-hook* to nil.
(%i5) timedate(+8);
(%o5) 2010-04-18
10:56:08-08:00
(%i6) timedate(+7);
(%o6) 2010-04-18
11:56:27-07:00
-------------------------------
My actual interest is using timedate() to put a
time stamp on runs of batch files. Looking back
at my tex file record of these runs, having that
time stamp helps me sort out what came first in
my thinking. And I actually only need the mo-day-year
part of the time stamp.
So I use the code :
mydate : apply ('sconcat, rest (charlist (timedate()),-15))$
with the effects (with the lisp patch in place):
---------------------------
(%i7) mydate : apply ('sconcat, rest (charlist (timedate()),-15))$
Maxima encountered a Lisp error:
Error in DECODE-UNIVERSAL-TIME [or a callee]: NIL is not of type NUMBER.
Automatically continuing.
To reenable the Lisp debugger set *debugger-hook* to nil.
(%i8) mydate : apply ('sconcat, rest (charlist (timedate(+7)),-15))$
(%i9) mydate;
(%o9) 2010-04-18
-------------------------------------------
I would like to include the construction of mydate
as a simple example of string manipulation in the next
revision of ch. 1 of maxima by example, as well as
mention the cures you have provided for windows
users.
Thanks again,
Ted