IV. Special Graphs
E. Piecewise Defined Functions
A function such as the one below is called a piecewise function and can be entered in a TI86. However, it does require careful entry. Some of the key entries are defined in more detail on other pages. So, if you need more explanation, just follow the links.
Example: Graph the function . You will need to access the TEST menu by pressing . You will enter each part of the function in conjunction with the TEST menu. The parentheses are important. You should graph these functions in DOT mode so that the calculator does not attempt to connect two pieces that should not be connected. Two screens are shown in the second panel so that you can see the entire function.
Test Menu.

Enter the function.
Put in DOT mode. 
Graph with ZDECM.

Graph with ZSTD.

Example: Graph the function .
Three screens are shown for entering the function so that you can see the entire function. It is important that you use the parentheses properly.
Enter the first part. Enter the second part. Enter the third part. Graph with ZSTD.