To define or edit a function, follow these steps:

1. Press c to display the Y= editor.

2. With a function defined in the function editor, press a Ä to display the table.

3. Press right arrow key › to the y= column of the function to be edited.

4. Press the up arrow key } to highlight the function line and press =.

5. The function will display in the edit line at the bottom of the screen. Make the desired edits, and press = to complete the edits.