Texas Instruments TI-89 Manual Book page 127

Clearing a Function
Note: ƒ 8 does not erase
any stat plots (Chapter 16).
Shortcuts to Move
the Cursor
From the Home
Screen or a
Program
Tip: User-defined functions
can have almost any name.
However, if you want them
to appear in the Y= Editor,
y1(x)
use function names
y2(x)
, etc.
110 Chapter 6: Basic Function Graphing
From the Y= Editor:
To erase:
A function from
the function list
A function from
the entry line
All functions
You don't have to clear a function to prevent it from being graphed.
As described on page 111, you can select the functions you want to
graph.
From the Y=Editor:
Press:
¥ C or
¥ D
You can also define and evaluate a function from the Home screen or
a program.
¦
Use the
Define
"Graphing a Function Defined on the Home Screen" and
"Graphing a Piecewise Defined Function" in Chapter 12.
"Overview of Entering a Function" in Chapter 17.
¦
Store an expression directly to a function variable. Refer to:
,
"Storing and Recalling Variable Values" in Chapter 2.
"Creating and Evaluating User-Defined Functions" in
Chapter 5.
Do this:
Highlight the function and press 0 or M.
Press M once or twice (depending on the
cursor's location) and then press ¸.
Press ƒ and then select
When prompted for confirmation, press ¸.
To:
Go to function 1 or to the last defined function,
respectively. If the cursor is on or past the last
defined function, ¥ D goes to function 99.
and commands. Refer to:
Graph
8:Clear Functions .