alt Hacker News> It's not possible to learn anything about other elements when performing binary search, _except_ the only thing there is to learn: if the target is before or after the recently compared element.
You have another piece of information, you don't only know if the element was before or after the compared element. You can also know the delta between what you looked at and what you're looking for. And you also have the delta from the previous item you looked at.
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Assuming your key space is anything like randomly distributed.
Thinking about it--yeah, if you can anticipate anything like a random distribution it's a few extra instructions to reduce the number of values looked up. In the old days that would have been very unlikely to be a good deal, but with so many algorithms dominated by the cache (I've seen more than one case where a clearly less efficient algorithm that reduced memory reads turned out better) I suspect there's a lot of such things that don't go the way we learned them in the stone age.
And you always start off knowing the total length of the array, and the width of the datatype.
Actually deciding what to do with that information without incurring a bunch more cache misses in the process may be tricky.