I'm on an Ubuntu Linux PC, and get the same wrong result as you.
I could not work out what the description of '%y' really ment, so I did
not realize this was operating system specific in this sense. Anyway,
I'll find a way to work around this bug.

Have a nice weekend,
Kare


On Fri, 2008-05-23 at 10:41 +0100, Prof Brian Ripley wrote:

> On my Linux box:
> 
> > strptime("010169", format = "%d%m%y")
> [1] "1969-01-01"
> > strptime("311268", format = "%d%m%y")
> [1] "2068-12-31"
> 
> >From the help page:
> 
>       '%y' Year without century (00-99). If you use this on input, which
>            century you get is system-specific.  So don't!  Often values
>            up to 69 (or 68) are prefixed by 20 and 70 (or 69) to 99 by
>            19.
> 
> If all else fails, read the documentation (but the posting guide asks you 
> to do that before posting).  Elsewhere on that help page it refers you to 
> your OS documentation -- the posting guide asked for your OS 'at a 
> minimum', but as you didn't follow it so we have no idea which you used.
> 
> On Fri, 23 May 2008, Kåre Edvardsen wrote:
> 
> > Hi r-helpers...
> >
> > Why do I get this strange huge jump of 36524 days when changing "origin"
> > from 1969-01-01 to 1968-12-31. It should still be close to zero! This
> > really messes up my calculations of follow-up times in my analyses.
> >
> >> julian(strptime("010169", format = "%d%m%y"),origin =
> > as.Date("1969-01-01"))
> >> Time difference of -0.04166667 days
> >
> >> julian(strptime("311268", format = "%d%m%y"),origin =
> > as.Date("1968-12-31"))
> >> Time difference of 36524.96 days
> >
> >
> > Cheers,
> > Kare
> >
> > 	[[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
> 

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