IV. Special Graphs
B. Greatest Integer Function
The greatest integer function (also called a step function) is actually a piecewise defined function with a special definition. The function has the notation f(x)=x or f(x)=[[x]] when it is written, but the TI83 and the TI84 designate this function by using f(x)=int(x) and is found in the MATH NUM menu. This function is the greatest integer less than or equal to x. So, f(1)=1 and f(1.4)=1. Since this is a piecewise function you should use DOT mode.
Example: Graph the function f(x)=x (the greatest integer function.) Make sure that you use DOT mode.
Access
int( using
MATH  NUM 5 
Enter
the function.

Graph
with ZDecimal.

Without
DOT
(not good). 