Hi,
Yep. This was a bug which was apparently fixed in the srfi-19 reference
implementation quite some time ago. However, the current reference
implementation for date->julian-day doesn't work either. Anyway, I've
made a change to my working copy of CVS HEAD, and attached is output
from cvs diff.
Regards,
Jon
Jon Wilson wrote:
Hi,
Take a gander:
guile> (date->string (current-date))
"Wed Jun 27 16:39:42-0400 2007"
guile> (date->string (julian-day->date (date->julian-day
(current-date))))
"Wed Jun 27 12:39:43-0400 2007"
Offset by four hours from one another. Of course, the four hours
comes from the -0400 time zone. But clearly one of the two functions
is taking the time zone into account in a different manner from the
other function, leading to this discrepancy.
Similarly:
guile> (exact->inexact (current-julian-day ))
2454279.36203873
guile> (exact->inexact (date->julian-day (julian-day->date
(current-julian-day ))))
2454279.19553665
Nothing changes if I add the timezone specification to the
julian-dat->date function: (julian-day->date X -14400). I'm going to
go look at SRFI-19, and see if I can figure out if this is really a
bug or a design flaw. If it is a bug, I'll take a look at fixing it
and submitting a patch soon.
Regards,
Jon
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Index: srfi-19.scm
===================================================================
RCS file: /sources/guile/guile/guile-core/srfi/srfi-19.scm,v
retrieving revision 1.27
diff -r1.27 srfi-19.scm
814c814,815
< (year (date-year date)))
---
> (year (date-year date))
> (offset (date-zone-offset date)))
817c818,819
< (+ (/ (+ (* hour 60 60)
---
> (+ (/ (+ (- offset)
> (* hour 60 60)
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