Texas Instruments TI-89 Manual page 5

TI-89 Guide
substitutes that value when the expression is evaluated. All user-defined variables are stored in a
1
folder called
MAIN
name of a variable, press
using to move the cursor to the name of the variable, you can delete, copy, rename, etc. using
▼
the key on the
F1 [Manage]
Deleting a single variable: Suppose we want to delete the variable
a. Go to the
VAR-LINK
by first highlighting it and then pressing
and
ENTER ESC .
or different variables from what is shown to the right.)
The "with" operator, which prints as
order to evaluate expressions so that you do not have to delete the variable when you finish. Ac-
cess this operator by pressing the key directly under
Evaluate 5.3r – 2.1h
typing in the instructions shown to the right. Access
CATALOG = (A)
see that and are not defined variables.
r h
5. ERROR MESSAGES When your input is incorrect, the TI-89 displays an error message.
If you have more than one command on a line without using a colon
(:) to separate them, an error message results when you press
Press
ENTER .
If you try to store something to a particular memory location that is
being used for a different type of object, an error results. (In the
screen shown to the right, the variable abc was defined as a data list,
so a number cannot be stored to it.) Consult either Trouble-Shoot-
ing the TI-89 in this Guide or your TI-89 Owner's Guidebook.
•
The error message shown directly above usually occurs when you are executing a program
that is trying to store a value to a variable that you have previously defined as some other
type of object. Rename the other type of object and rerun the program. Remember, store
only numbers to single-letter names to avoid problems such as these.
A common mistake is using the negative symbol
−
subtraction sign
message, but a wrong answer results. The negative sign is shorter
and raised slightly more than the subtraction sign.
1
We work only in the MAIN folder. If you wish to create different folders, see pages 88-90 of the TI-89 Guidebook.
Copyright © Houghton Mifflin Company. All rights reserved.
unless you create other folders to hold them. If you cannot remember the
−
2nd (VAR-LINK)
screen. We illustrate by deleting the variable
VAR-LINK
screen with
2nd
F1 [Manage] 1 [Delete]
(Note that your
MAIN
, gives a way to temporarily store values into a variable in
"|"
2
for for r = 6 and then for r = 2.9 and h = 7 by
Press
▼ ENTER .
and correct the error.
ESC
or vice-versa. The TI-89 does not give an error
and the names of the variables are listed. After
−
Delete a
(VAR-LINK).
folder may contain more
= .
with
"and"
−
and
2nd (VAR-LINK)
−
instead of the
( )
TI 89-5
a: