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Posted by Robert Newson on 06/24/07 07:00
Jerry Stuckle wrote:
....
> And while I agree with the astronomers that there is no reason for a
> negative leap-second, programmers need to be aware it can happen!
Shirley the correction for a negative leap-seacond would be to put the clock
/forward/ 1 second? ie /increase/ the time?[1]
The only thing is: does the time() clock actually adjust for leap seconds?
Leap days (and DLS) are "fixed" in the conversion to localtime; would leap
seconds be "fixed" at the same time?
[1] Consider that what leap days do is cause the day to be fast if you don't
correct; the "correction" causes 1 Mar becomes 29 Feb, 2 Mar becomes 1 Mar,
etc - the "correction" is to take the clock /backward/ by 86,400[2] seconds
by inserting an extra 86,400 seconds. Similarly leap-seconds: they insert a
second to take the clock backwards: the [physical] day is 86,401[2] seconds
long (24:00:01); a negative leap-second would require the day to be
86,399[2] seconds long (23:59:59) - the only way this could shirley occur is
if the earth's rotation /speeded up/...or the timekeepers (atomic clocks?)
slowed down[3]?
[2] Rounded to the nearest second.
[3] Or an error was made in adding a leap second in the first place?
Or have I totally misunderstood what leap seconds (and days) do?
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