Texas Instruments TI-73 Explorer Quick start guide

6/26/01 ©1999, 2001 Texas Instruments
Matrices
for the TI-73
Getting Started
Start here
How To…
Find Installation Instructions
Move Between Matrix Application Screens
View and Edit a Matrix
Use Matrices with Expressions
Display and Copy Matrices
Use Math Functions with Matrices
Use the Matrix MTH Operations
Delete a Matrix
More Information
Uninstalling the Application from the TI-73
Error Recovery
Customer Support
TI

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Important Information
Texas Instruments makes no warranty, either expressed or
implied, including but not limited to any implied warranties of
merchantability and fitness for a particular purpose, regarding
any programs or book materials and makes such materials
available solely on an “as-is” basis.
In no event shall Texas Instruments be liable to anyone for
special, collateral, incidental, or consequential damages in
connection with or arising out of the purchase or use of these
materials, and the sole and exclusive liability of Texas
Instruments, regardless of the form of action, shall not exceed
the purchase price of this product. Moreover, Texas Instruments
shall not be liable for any claim of any kind whatsoever against
the use of these materials by any other party.
This graphing product application (APP) is licensed. See the
terms of the license agreement.
Copyright © 1999, 2001 Texas Instruments Incorporated.

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Where to Find Installation Instructions
You can find detailed instructions on installing Flash applications
at education.ti.com/guides.

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Getting Started: Systems of Linear Equations
Use the Matrices application to solve the system of linear
equations:
X + 2Y + 3Z = 3
2X + 3Y + 4Z = 3
Enter the coefficients as elements in a matrix, and then use rref(
to find the reduced row-echelon form.
Steps
Keystrokes
Display
1. Run the Matrices
application.
9, highlight
MATRICES
and press
b, then
press any key
2. Display the MATRIX EDT
menu, and select the [A]
matrix.
""1

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Steps
Keystrokes
Display
3. Define a 2×4 matrix. The
rectangular cursor
indicates the current
element. Ellipses (...)
indicate additional
columns beyond the
screen.
2 b
4 b
4. Enter 1for the first
element. The rectangular
cursor moves to the
second column of the
first row.
1 b
5. Complete the first row
for X +2Y +3Z =3.
6. Enter the second row for
2X +3Y +4Z =3.
2 b
3 b
3 b
2 b
3 b
4 b
3 b
7. Display the Matrix Home
screen.
9:

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Steps
Keystrokes
Display
8. Clear the screen, if
necessary.
9. Display the MATRIX MTH
menu. Press $to wrap
to the end of the menu,
and then select B:rref(.
:
9"
$
$$$$$$
b
10. Display the MATRIX NAME
menu and select matrix
[A]. Then complete the
calculation. The reduced
row-echelon form of the
matrix is:
1X +0Y N1Z =L3so
X=L3+Z
0X +1Y +2Z =3so
Y=3N2Z
91
Eb

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Running or Quitting the Application
Running the Application
After installing the application:
1. Press 9.
2. Select the Matrices application. An
informational screen appears.
Note
If you ever need technical support, you may need the version
number shown on this screen.
3. Press any key to display the Matrix Menu
screen.

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Quitting the Application
To exit the Matrices application and return to the TI-73 Home
screen, either:
•Press -l.
–or –
•On the Matrix Menu screen, highlight
HLP. Then select 2:Quit.
Any matrices or other variables that you stored while using the
Matrices application are retained in memory. Matrices are stored
as application variables (App vars). After quitting the application,
you cannot use a stored matrix from the TI-73 Home screen; you
must run the Matrices application to access a matrix or perform a
matrix calculation.

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Matrices Application Screens and How to
Move Between Them
The three primary screens used in the Matrices application are
shown below. Notice the keys used to move from one screen to
another.
The Matrices application
starts on this screen.
The Matrix Home
screen replaces the
normal TI.73 Home
screen. Use this
screen to perform all
calculations while
running the Matrices
application. From this
screen, you can also
access most of the
normal TI.73 menus.
The Matrix Edit
screen lets you edit an
existing matrix or
create a new one.
The Matrix Menu
screen lets you access
menus to:
•Select matrix names
for use in a
calculation
•Select matrix math
operations.
•Edit or create a
matrix.
•View online Help.
9
:
Select from
EDT menu
9

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Viewing Online Help
To view online Help, highlight HLP on the Matrix Menu screen.
Then select 1:Help.
At any time, press -lto
exit Help and return to the
Matrix Menu screen.
Press "(next) and !(back) to
move through the Help, one page
at a time. On the last page, "
returns to the Matrix Menu screen.

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Defining a Matrix
What Is a Matrix?
A matrix is a two-dimensional array. You can define, display, or
edit a matrix using the Matrix Edit screen. You can also define a
matrix directly in an expression. The Matrices application for the
TI-73 has six matrix variables, [A] through [F]. A matrix,
depending on available memory, can have up to 100 elements in
any arrangement of rows and columns (with a maximum of 99
individual rows or columns). You can store only real numbers in
a matrix.
Defining a New Matrix
Before you can define or edit a matrix in the editor, you must
select the matrix name. From the Matrix Home screen:
1. Press
9""to display the MATRIX EDT menu (not MATRIX
NAME).
NAME lets you select the
name of an existing matrix
for use in a calculation,
not for creating or editing.
(You can perform a matrix
calculation only on the
Matrix Home screen.)
Matrix [C] is already
defined as a 2x4 matrix.
EDT lets you select
a matrix to create or
edit.

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2. Select the matrix you want to define. Use #or $to highlight
the corresponding number and then press b, or press
that number key. The Matrix Edit screen is displayed.
When you edit or create a matrix, the cursor highlights the
number of rows.
3. Accept or change the number of rows.
•To accept the value, press b.
•To change the value, type the number of rows and then
press b.
The cursor moves to the number of columns.
Sets the number of
rows, up to 99.
Sets the number of
columns, up to 99.

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4. Accept or change the number of columns. When you press
b, the cursor moves to the first matrix element.
5. Type the value (or an expression) for each element and
press b, one row at a time. Each time you press b,
the cursor moves to the next element in the row. At the end
of a row, the cursor moves to the next row.
6. After entering the last element, press 9to return to the
Matrix Menu screen. You can then press :to display the
Matrix Home screen.
To change a value, use !, ", #,
and $to highlight that element
and then enter a new value (or
press
band then edit the
current value).
In a new matrix, all
elements are zero.

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Viewing and Editing a Matrix on the Matrix
Edit Screen
Viewing an Existing Matrix
On the Matrix Edit screen, select the matrix. As necessary, use the
cursor keys to move the rectangular cursor from one matrix
element to the next.
When the rectangular cursor highlights an element (and an edit
cursor is not shown on the bottom line), you can use the
following keys:
Key
Description
!or "
Moves the cursor within the current row.
#or $
Moves the cursor within the current column.
•On the first row, $moves the cursor to the number of columns
•On the number of columns, $or !moves the cursor to the
number of rows.
Dimensions of the matrix.
Ellipses (...) in the left or right column indicate
additional columns.
#or $in the right column indicates additional rows
The full value of the highlighted element is shown
on the bottom line.

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Key
Description
b
or
:
or
any entry
character
Lets you edit the highlighted element, and activates the edit cursor
on the bottom line of the screen.
•bretains the current value in the bottom line so that you
can modify it.
•:clears the bottom line so you can enter a new value.
•Any entry character clears the bottom line and places that
character on the line.
Editing a Matrix Element
To edit a matrix element, you must first activate the edit cursor.
1. Select the matrix from the Matrix Edit menu, and then enter or
accept the number of rows and columns.
2. Press
!, $, ", and #to highlight the element.
3. Press either
b, :, or an entry key to activate the
edit cursor on the bottom line.
4. Change the value of the matrix element using the editing
keys described below. You can enter an expression, which is
evaluated when you move the cursor to another element.
Note
If you edit a value by mistake and want to restore the original
value, press :b.

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5. Press
b, $, or #to move to another element.
When the edit cursor is shown on the bottom line, use the
following keys to edit the value:
Key
Description
!or "
Moves the edit cursor within the value.
#or $
Stores the value displayed on the bottom line to the matrix element;
deactivates the edit cursor and moves the rectangular cursor within
the column.
b
Stores the value displayed on the bottom line to the matrix element;
deactivates the edit cursor and moves the rectangular cursor to the
next row element.
:
Clears the value on the bottom line.
Any entry
character
Places that character at the location of the edit cursor.
-m
Activates the insert cursor.
/
Deletes the character under the edit cursor.

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Using Matrices with Expressions on the Matrix
Home Screen
Using a Matrix in an Expression
To use a matrix in an expression, either:
•Copy the name of an existing matrix from the MATRIX NAME
menu.
•Type the matrix elements directly from the keyboard.
An expression can perform a maximum of two operations that
create or return a matrix. For example:
[ [1,2] [3,4] ] Ü[A] and [ [1,2] [3,4] ] ¦3
are valid because they contain two matrix operations (the input
matrix is created in the calculator’s memory, and so is the
resulting output matrix).

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If an expression has three or more such operations, an error
occurs. In most cases, however, you can perform the operations
successfully by breaking them into separate pieces. For
example:
An error occurs for:
Instead, enter:
[ [1,2] [3,4] ] + [ [5,6] [7,8] ]
[ [1,2] [3,4] ] Ü[A]
[ [5,6] [7,8] ] Ü[B]
[A] +[B]
augment([ [1,2] [3,4] ] , [ [5,6] [7,8] ])
[ [1,2] [3,4] ] Ü[A]
[ [5,6] [7,8] ] Ü[B]
augment( [A] , [B] )
identity(3) * randM(3,3)
identity(3)
Ü[A]
randM(3,3)
Ü[B]
[A] * [B]
Note
These expressions cause an error because they contain three
matrix operations (two input matrices and one result matrix).

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Typing a Matrix Directly from the Keyboard
On the Matrix Home screen, use the syntax:
[ [element1,1,...,element1,n],...,[elementm,1,...,elementm,n] ]
Any expressions are evaluated when you press b. For
example:
To store a matrix directly to a matrix variable, use X. For
example:
Use [(press &) to
begin the matrix.
Use ](press ') to
end the matrix.
Note: The closing ]]are
not necessary at the end of
an expression or preceding
Ü(X).
Use [ ] to enclose the elements for each
row. Use commas to separate the
elements. An element can be an
expression.
Note: At the start, [[begins the matrix
and then begins the first row.
The commas that you
must enter to separate
elements are not
displayed on output.
Select the matrix from the
Matrix NAME menu or type it
directly. Press &and '
to type [and ].

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Accessing a Specified Matrix Element
On the Matrix Home screen, you can store a value to, or recall a
value from, a specified matrix element. The element must be
within the defined matrix dimensions. Use the syntax:
[matrix] (row,column)