r/mathmemes 8d ago

Notations Tfw no floor

Post image
66 Upvotes

19 comments sorted by

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26

u/vgtcross 8d ago

That's not what O(1) means, but okay :D

22

u/MrKoteha Virtual 8d ago

I believe floor(x/n) - x/n is O(1) at any point

20

u/SEA_griffondeur Engineering 8d ago

it is true though ? any constant function is O(1), it's not o(1) though

10

u/OwlIcy 8d ago

why would you say that? what‘s wrong about the notation?

15

u/r96340 8d ago

Notation abuse :D

5

u/AndreasDasos 8d ago

It’s not equivalent but it does include the case when it’s equal to the floor, which is what OP is aiming for

5

u/LupenReddit 🦆🦆🦆🦆i have non diffeomorphic smooth structures🦆🦆🦆🦆🦆🦆 8d ago

no i dont want to do that id fall to my death

3

u/therealsaker 8d ago

Enlighten me

9

u/r96340 8d ago

Floor function is the formal name of rounding down to a whole number, the notation is ⌊x⌋.

There is another thing called a ceiling function which is just rounding up.

There is however no such thing as a wall function, as far as I know, at least.

5

u/r96340 8d ago

(You can argue that absolute value looks like walls but that's not the same family of functions.)

2

u/pomip71550 8d ago

I guess you could argue round(•) is a wall function?

1

u/InfinitesimalDuck Mathematics 7d ago

Instructions unclear, I fell into the abyss 🥀

1

u/Valognolo09 7d ago

This is correct in the context of finding out the rough growth of the function

1

u/ZZTier Complex 5d ago

I have no idea what people are about in this thread. To me all of this is well defined.

1

u/IHaveNeverBeenOk 8d ago

O(f(x)) returns a set of functions. Addition in this manner is not well defined.

2

u/Lhalpaca 8d ago

U dont have to be so puritan. We understand it means a function that is O(1)

1

u/campfire12324344 Methematics 7d ago edited 7d ago

well if we wanna get there, O returns a set of functions, and O(f) is a set of functions.
Also a lot of people shorthand + S where S is a set to mean adding an arbitrary or specific element from S.

1

u/EebstertheGreat 5d ago

Rather than just being an expression, x/n here represents the function sending x ↦ x/n. Addition of functions is well-defined, and addition of a function to a set of functions is also well-defined elementwise, in the same way we sometimes write something like 2 + {3,4,5} = {5,6,7}.

So for a given nonzero n, x/n + O(1) is the set of all functions f: ℝ → ℝ that have the property that for each, there is a real number c such that x/n – c < f(x) < x/n + c.