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Re: unix time in plot (an Octave problem?)
From: |
Vic Norton |
Subject: |
Re: unix time in plot (an Octave problem?) |
Date: |
Mon, 20 Jul 2015 17:53:36 -0400 |
On Jul 20, 2015, at 4:22 PM, Mike Miller <address@hidden> wrote:
> On Mon, Jul 20, 2015 at 15:39:07 -0400, Vic Norton wrote:
>> I put the unix times above in the following Octave script:
>> printf("This looks right. It's what I want.\n");
>> printf(" %s\n", strftime("%Y-%m-%d %X %Z", gmtime(1420027200)));
>> printf(" %s\n", strftime("%Y-%m-%d %X %Z", gmtime(1435665600)));
>> printf(" %s\n", strftime("%Y-%m-%d %X %Z", gmtime(1451563200)));
>> printf("But shouldn't all the %%z time zones read +0000?\n");
>> printf(" %s\n", strftime("%Y-%m-%d %X %z", gmtime(1420027200)));
>> printf(" %s\n", strftime("%Y-%m-%d %X %z", gmtime(1435665600)));
>> printf(" %s\n", strftime("%Y-%m-%d %X %z", gmtime(1451563200)));
>> The results are a bit disturbing:
>> This looks right. It's what I want.
>> 2014-12-31 12:00:00 UTC
>> 2015-06-30 12:00:00 UTC
>> 2015-12-31 12:00:00 UTC
>> But shouldn't all the %z time zones read +0000?
>> 2014-12-31 12:00:00 -48038628
>> 2015-06-30 12:00:00 -48040837
>> 2015-12-31 12:00:00 -48053659
>> See, for example,
>> http://search.cpan.org/~dexter/POSIX-strftime-GNU-0.0301/lib/POSIX/strftime/GNU.pm
>
> I agree, I get the same output.
>
> Two things:
>
> 1. Note that "%z" is not documented in "help strftime", although I
> agree it is reasonable to expect it to work if you're familiar with the
> standard C function of the same name.
>
> 2. We use the gnulib implementation of strftime, which I think is where
> the bug lies. If you're willing, you could work up a minimal example to
> verify that the bug lies in gnulib, report it to the gnulib project,
> and we can absorb the fix in Octave.
>
> If not, at least report a bug on the Octave bug tracker.
>
> Thanks for the demonstration,
>
> --
> mike
Thanks for the advice, Mike. I don't know anything about gnulib, but I
did report the bug at <https://savannah.gnu.org/bugs>, if that's what
you mean by the Octave bug tracker. Apparently the %z is nonstandard.
In Perl you need the POSIX-strftime-GNU-0.0301 package.
--
Vic