Yep, you're right, including ceil() was misleading of me, if not downright wrong. I technically did not specify which side the interval is open on. But practica

Yep, you're right, including ceil() was misleading of me, if not downright wrong. I technically did not specify which side the interval is open on. But practically and realistically, in pretty much any scenario it will be a half-open interval that excludes the upper bound, and you have to go out of your way to get it the other way around (at which point you probably well know yourself to use ceil() instead of floor()).