[Octave-bug-tracker] [bug #36954] datenum / datevec convert date-time string incorrectly during hour lost to DST

[Philip Nienhuis]

Follow-up Comment #16, bug #36954 (project octave):

Here's some timings (on Win7 64-bit, octave-4.3.0+ as of late May)

I used the following script that I ran twice w. & w/o patch:

t_tot = t_max = 0;
t_min = Inf;
dats = [datenum(2009, 1, 1, 0, 1, 0) : (1/24/6) : datenum(2009, 12, 31, 23,
51, 0)];
for ii=1:100
  tic; datv = datevec (dats); tt = toc;
  t_tot += tt;
  t_min = min (t_min, tt);
  t_max = max (t_max, tt);
endfor
t_avg = t_tot / 100;
t_tot
t_min
t_max
t_avg


Without my patch:
+verbatim-
Run 1:

>> t_tot
t_tot =  1.1781
>> t_min
t_min =  0.011000
>> t_max
t_max =  0.029002
>> t_avg
t_avg =  0.011781

Run 2:

>> t_tot
t_tot =  1.1891
>> t_min
t_min =  0.011000
>> t_max
t_max =  0.032002
>> t_avg
t_avg =  0.011891


... and with the patch:

Run 1:

>> t_tot
t_tot =  1.1771
>> t_min
t_min =  0.011000
>> t_max
t_max =  0.028002
>> t_avg
t_avg =  0.011771

Run 2:

>> t_avg = t_tot / 100;
>> t_tot
t_tot =  1.1981
>> t_min
t_min =  0.011000
>> t_max
t_max =  0.021002
>> t_avg
t_avg =  0.011981


I'd say there's no discernable slowdown.

Just to note, looking in the cod for datevec I see in subfunc
__date_vfmt2sfmt__ already 5 consecutive calls to regexprep and 3 to strrep.
So those two I add can't make that much difference, can they.


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