Tupper’s self-referential formula is a self-referential formula defined by Jeff Tupper that, when graphed in two dimensions, can visually reproduce the formula itself. It is used in various math and computer science courses as an exercise in graphing formulae.
The formula is an inequality defined by:
where [.] denotes the floor function and mod is the modulo operation. If one graphs the set of points (x,y-k) with
such that they satisfy the inequality given above, the resulting graph looks like this: