TI-89 Calculator Tutorial
This TI-89 calculator tutorial is intended to acquaint you with some of the skills and tools that
will be helpful during your engineering education and beyond. The practical will test you over a
subset of the following skills (which are highlighted in BOLD):
1. Matrix Algebra including the following operations:
 Matrix addition
 Matrix multiplication
 Matrix inverse
 Solutions of linear equations through rref (reduced row echelon form)
2. Complex number/polynomial operations:
 Rectangular to polar conversion
 Polar to rectangular conversion
 Magnitude (Modulus) and Angle (principal argument)
 Roots of polynomials (use csolve())
3. Calculus/Algebraic operations
 Symbolic and numerical integration
 Derivatives
 Solve nonlinear equation(s)
4. Graphing


Graph polynomials and other single variable functions of the form y=f(x).
Change the x-axis and y-axis scales to a specified range.
5. Menu Functions/Programming
 Write a simple “program” to evaluate a function of the form y=f(x).
 Add a function to the custom menu.
Matrix Operations: Example 1: Storing a matrix in a variable makes it possible to more easily
perform a variety of operations on that matrix with a minimum number of keystrokes.
1
2
Example: #1 Let the matrix A be defined as A  
2
3
3
, and let the matrix B be
4 
 3 4 


defined as B  6 2 . Calculate C  AB , and D  BA .


1 8


Enter the A matrix by using the command shown (the arrow is the STO key) below. After you hit
the “enter” key you should see the following display.
Repeat this process for the B matrix. After both are entered you should be able to enter the next
command (shown below) to obtain the result for the C matrix.
The D matrix result is given by
Matrix Operations: Example 2: Calculate the inverse of the C matrix defined in example 1.
Matrix Operations: Example 3: There’s more than one way to solve a system of linear equations
on the TI-89 calculator. I feel that the row-reduced echelon form (rref) is the most efficient way
to solve linear equations in terms of using fewer keystrokes. See the “Solving a System of Linear
Equations” example on page 61 of the TI-89 manual. (Note: The page numbers in your manual
may be different, depending on when you purchased your calculator. Please let me know and I
will update this document.)
Complex Numbers: Example 1: Convert the expression 2e
forms.
j 4
 2 j  6 to standard and polar
Standard Form: Use the MODE button to change the Complex format to rectangular.
(Rectangular is the same as standard form). Make sure your calculator is in radian mode,
otherwise you will get a domain error when you calculate the complex exponential term. Enter
the expression to obtain the result shown below.
Complex Form: Now use the MODE button to change the complex format to polar. You should
get the result shown below (use the “approximate equal sign” instead of “enter”):
Complex Numbers: Example 2. The book uses the word “modulus” to describe the “magnitude”
component of a complex number. For complex numbers, the absolute value sign is also used to
mean “magnitude”. The book also uses the words “principal argument” to mean the angle of a
complex number. The TI 89 function for “modulus” is abs() and the TI 89 function for “principal
argument” is angle().
Calculus Operations: Example 1: Find the derivative of f ( x )  x 3 cos(2 x ) with respect to x .
From the catalog menu, find “ d( differentiate” and select it. Your command line and result
should look like the following (you’ll have to “scroll” to see the entire answer).
Solve Nonlinear equation: Example 1: Find the value of x that solves the equation
1
 0.03
x  2000
Graphing: See the example on page 7 of the TI manual.
Simple Program: See the example on page 85 of your manual. After you’ve entered the
definition of the “cube(x)” example (from page 85) you should verify its operation. I also want
you to notice that you can access the function through the program editor. Choose “APPS” –
“Program Editor” – “Open”, and you will get the following screen.
Select “Program” so that a drop-down menu gives you a choice between “Program” and
“Function”. Select “Function”, then select “Variable” so that you get a drop-down menu that has
“cube” as a choice. (Your variable list may ONLY have cube as a choice or it may have several
other choices depending on what you’ve programmed into your calculator.)
Select “cube” and enter “OK” to get the program editor for the cube function.
From the program editor you can change your “custom” function and if needed and more
complicated conditional and branching statements. On the practical, however, you just have to be
able to program a simple function of the form y=g(x).
Add a function to the Custom menu:
Adding a custom menu seems really complicated when you look at the manual. Actually, its
pretty easy if you use the “copy” function and the program editor.
To get started, lets look at the default custom menu. Hit 2nd – Custom and examine the menu that
appears at the top of the calculator. Under F2 there’s a “title” that reads “f(x)”. If you go to the
F2 menu, you get options that say 1: f(x), 2: g(x), .. and so on.
Let’s make our own custom menu that replaces the first two entries under the f(x) title with the
abs( and the angle( functions (that are built-in to the TI-89). I intentionally left the closing
brackets off of both functions to make them easier to use from the custom menu.
To modify the default custom menu, you first need to copy the commands that generate it. You
can do this from the “clean-up” menu. To do this, turn off the custom menu by hitting 2nd –
Custom. Then go to F6 – “Restore custom default”. At this point a “bunch of stuff” shows up on
the command line. This is the command that generates the custom menu. At this point hit the
ENTER key and you will see that the entire text listing is highlighted. Use the Green-Copy key
to copy this command.
Next hit the APPS – Program Editor – New
A custom menu is a “program” type, so you don’t have to change that selection. Let’s store the
custom menu under the “main” (default) folder, so again, you don’t need to make a change. Enter
a variable name in the “Variable” dialog box. In my case, I’m choosing “egr” as shown below:
Then enter OK. For this custom menu, you don’t need any input arguments to the function.
Move the cursor to the line just past the one that says “Prgm” as shown by the arrow.
The paste in the “default custom menu command” that you had already copied using the GreenPaste command.
You get a big mess like the one shown below:
At this point, modifying the custom menu is a matter of finding the “title” and “item” that you
want to change. For this example we wanted to change the first item under the “f(x)” title to
“abs(“, and the second item under the “f(x)” title to “angle(“. Find these items and replace them
as shown. The dark area shows the new text exactly as it should appear.
That’s all there is to it. You can then leave the program editor by hitting the HOME key.
To make your menu appear issue the command egr() , press enter, and then hit F2. You should
get the result shown below with the abs and angle functions added.
Note that when you select either “abs( “ or “angle(“ from the menu you will see the function
name pasted onto the command line and ready for use. You have to remember to add the closing
bracket yourself.
To clear the egr() menu just enter 2nd-Custom and the “regular” menu should show up again.
Hopefully you’ll see that its not that bad to customize the menus. You can even generate a
custom menu for each class so that you can use your calculator more efficiently.