[tz] How to compute the moment of the next DST change

Paul Eggert eggert at cs.ucla.edu
Wed Apr 3 02:45:11 UTC 2013

On 04/02/2013 12:21 PM, Simon Perreault wrote:

> Looking at the source code of "calendar-next-time-zone-transition",
> it looks very error prone to me. Am I reading the comments right?
> It initializes a binary search with the results of a heuristic?

Yes.  It's a heuristic that should work with all real-world time zone
histories (including all time zone histories in the tz database).
It won't work in general, though.

zdump uses a similar heuristic, if memory serves.

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