Complexity nomenclature

[Ola Fosheim Grøstad via Digitalmars-d]

On Friday, 4 December 2015 at 09:17:07 UTC, Ola Fosheim Grøstad 
wrote:
> On Friday, 4 December 2015 at 09:09:35 UTC, ZombineDev wrote:
>> and space complexity (the correctness is given). Otherwise, 
>> designing large systems becomes impossible, because all large 
>> systems have hard performance requirements.
>
> I am sorry to say this, but hard performance requirements 
> require O(1) on everything.

And even then you cannot assume that it is real time as the 
following is O(1):

if (full_moon()) sleep(1000);

So you can have an O(1) algorithm that occasionally triggers an 
expensive constant-time/memory path that causes big problems in a 
running system. You need a hard upper bound measured in cycles.