> In idealized algorithmic analysis, but not necessarily real life.
Big O notation is used for idealized algorithmic analysis. If you want to talk about real life, you can count cycles, seconds, watts etc.
> "Amortized O(1)," which I assume you concede is a commonly-used, meaningful and legitimate term, means "technically" an idealized O(>1) but O(1) in practice.
Yes, but I wouldn't take O(1) on its own to imply amortized complexity. Not that pretending that an array copy is O(1) in practice is particularly useful here since if you measure a copy operation in practice, you'll find that the time it takes scales roughly linearly with the size of the array. Not to mention that the space complexity is O(n) no matter how you put it.
> Such as an array small enough that it can be copied with 10 or fewer vector load/stores.
Are other cases conversely "uncommon"? My point here is that this is entirely your opinion and doesn't pertain to whether an array copy is O(1) or O(n) complex.
> Yes, that's my point. It's impossible to implement the example in less than idealized O(n) time, so O(n) and O(1) operations are equivalent complexity-wise WRT the entire method.
Big O notation is used for idealized algorithmic analysis. If you want to talk about real life, you can count cycles, seconds, watts etc.
> "Amortized O(1)," which I assume you concede is a commonly-used, meaningful and legitimate term, means "technically" an idealized O(>1) but O(1) in practice.
Yes, but I wouldn't take O(1) on its own to imply amortized complexity. Not that pretending that an array copy is O(1) in practice is particularly useful here since if you measure a copy operation in practice, you'll find that the time it takes scales roughly linearly with the size of the array. Not to mention that the space complexity is O(n) no matter how you put it.
> Such as an array small enough that it can be copied with 10 or fewer vector load/stores.
Are other cases conversely "uncommon"? My point here is that this is entirely your opinion and doesn't pertain to whether an array copy is O(1) or O(n) complex.
> Yes, that's my point. It's impossible to implement the example in less than idealized O(n) time, so O(n) and O(1) operations are equivalent complexity-wise WRT the entire method.
Not in terms of space.