Texas Instruments PLUS TI-89 - Manual (Page 221)

204 Chapter 12: Additional Graphing Topics
12ADDLGR.DOC TI-89/TI-92 Plus: Additional Graphing Tools (English) Susan Gullord Revised: 02/23/01 1:03 PM Printed: 02/23/01 2:15 PM Page 204 of 20
On the Y= Editor, all functions must be defined in terms of the
current graph mode’s “native” independent variable.
Graph Mode Native Independent Variable
Function x
Parametric t
Polar q
Sequence n
3D x, y
Differential Equation t
If you have an expression on the Home screen, you can use any of
the following methods to copy it to the Y= Editor.
Method Description
Copy and
paste 1. Highlight the expression on the Home screen.
Press ƒ and select 5:Copy .
2. Display the Y= Editor, highlight the desired
function, and press ¸.
3. Press ƒ and select 6:Paste . Then press ¸.
§ Store the expression to a Y= function name.
2x^3+3x^2ì4x+12!y1(x)
Define
command
Define the expression as a user-defined Y= function.
Define y1(x)=2x^3+3x^2ì4x+12
2£ If the expression is already stored to a variable:
1. Display the Y= Editor, highlight the desired
function, and press ¸.
2. Press 2 £. Type the variable name that
contains the expression, and press ¸ twice.
Important: To recall a function variable such as
f1(x) , type only f1 , not the full function name.
3. Press ¸ to save the recalled expression in the
Y= Editor’s function list.
Graphing a Function Defined on the Home Screen
In many cases, you may create a function or expression on the
Home screen and then decide to graph it. You can copy an
expression to the Y= Editor, or graph it directly from the Home
screen without using the Y= Editor.
What Is the “Native”
Independent
Variable?
Copying from the
Home Screen to the
Y= Editor
Tip : Instead of using ƒ 5
or ƒ 6 to copy and paste,
use:
TI - 89 : ¥ 6 or ¥ 7 .
TI - 92 Plus: ¥ C (copy) or
¥ V (paste).
Tip: To copy an expression
from the Home screen’s
history area to the entry line,
use the auto-paste feature
or copy and paste.
Tip: Define is available from
the Home screen’s
†
toolbar menu.
Tip: 2 £ is useful if an
expression is stored to a
variable or function that
does not correspond to the
Y= Editor, such as a1 or
f1(x)
.
Use the complete function
name: y1(x), not just y1.