HP 49g Graphing Calculator - Manual (Page 167)

Since the multiplication of matrices is not coimnutative, the order in
which you specify the matrices is important. The nmnber of colmuns in
the first matrix must equal the number of rows in the second matrix.
Multiplying two matrices
Enter the first matrix.
Press ®.
Enter the second matrix.
Press
1
.
2
.
3.
4.
The result is a matrix with the same number of rows as the first matrix
and the same number of columns as the second matrix. Each element in
the matrix is the product of the corresponding two elements in the
original matrices.
Finding the determinant oF a square matrix
1. Enter DET on the coiranand line.
2. Press
0 0.
3. Enter the matrix.
4. Press
The detenninant of a matrix can be used to solve a system of linear
equations. Another method is to use Gaussian elimination to generate the
row-reduced echelon form of a matrix. This is discussed in the next
section.
Solving a system of linear equations
A method of solving a system of linear equations is explained in chapter 6.
This method uses the numeric solver. The HP 49G also has a matrix
command for solving a system of linear equations. This command—
REEF—uses Gaussian eliixdnation to generate the row-reduced echelon
form of an augmented matrix.
You can use the RREF command in direct mode or in step-by-step mode.
(See “Setting step-by-step mode” on page 5-19 for instructions on setting
step-by-step mode.) In this mode, the HP 49G performs the Gaussian
elimination one step at a time. Before it performs each step, the HP 49G
displays a description of the action it is about to perform. You press
OK
to
action each step.
For example, suppose you have to solve the following system;
Vectors, lists, arrays, and matrices Page 8-11