How to describe a linear graph with some jumps

Question

To describe this simple with a little pseudocode (i'm better with software than mathematical notation, sorry):

f(x) = if (x <= 50%) then 0 else 1

This with a graph:

 100% |            x     x
  50% |
   0% | x   x      
      |___________________
        0%  33%   66%  100%

How would you describe this graph?

I'm trying to find the words to distinguish it from a flat linear graph:

 100% |
  50% | x    x    x    x  
   0% |
      |___________________
        0%  33%   66%  100%

and a non-flat linear graph

 100% |                     x
  75% |                x
  50% |           x     
  25% |      x
   0% | x
      |________________________
        0%  25%  50%  75% 100%

Answer 1

A piecewise constant function (a.k.a step function) is one possibility for any graph that is constant (flat) on different pieces.

You may also be interested in characteristic functions (a.k.a. indicator functions).