Greatest Integer Function

on the TI-89

The greatest integer function, y = [x], is represented on the TI-89 as either the int() function (found in the CATALOG) or the floor() function (found in the MATH menu). Examples are shown below.

You can find the int() function in the [CATALOG]. Of course you can always type a function name, too.

int() function in catalog

Here are some results of the [x] (int()) function.

int() function results

By default, the TI-89 will connect the segments of a graph. Since we know that the graph of y = [x] is discontinuous, press [F6-Style] and select "2: Dot".

graphing int(x)

Here is the resulting graph (in the "2: ZoomStd" window).

graph of y = int(x)

You won't find "int(" in the [2nd][MATH] menu, but the "6 floor(" function in the "1: Number" submenu is the same thing.

floor() function in math menu

Here are some results of the floor() function - compare to the int() function results above.

floor() function results

last update September 12, 2001 by JL Stanbrough