Texas Instruments TI-82 Manual page 22

Use the arrow keys or ENTER to move the cursor to a matrix element you want to change. At the right edge of the
screen in Figure 2.62, there are dashes to indicate more columns than are shown. Go to them by pressing ► as many
times as necessary. The ordered pair at the bottom left of the screen show the cursor's current location within the
matrix. The element in the second row and first column in Figure 2.62 is currently highlighted, so the ordered pair at
the bottom of the window is 2, . Continue to enter all the elements of matrix [A]
Leave the matrix [A] editing screen by pressing 2nd QUIT and return to the home screen.
2.6.2 Matrix Math: From the home screen you can perform many calculations with matrices. First, let's see matrix
[A] itself by pressing MATRX 1 ENTER (Figure 2.63).
Calculate the scalar multiplication 2[A] by pressing 2 MATRX 1 ENTER. To replace matrix [B] by 2[A], press 2
MATRX 1 STO➧ MATRX 2 ENTER, or if you do this immediately after calculating 2[A], press only STO➧
MATRX 2 ENTER (see Figure 2.64). Press MATRX ► ► 2 to verify that the dimensions of matrix [B] have been
changed automatically to reflect this new value.
Figure 2.63: Matrix [A]
Add the two matrices [A] and [B] by pressing MATRX 1 + MATRX 2 ENTER. Subtraction is similar.
Now set the dimensions of matrix [C] to 2×3 and enter this as [C]:
by [A], press MATRX 3 × MATRX 1 ENTER. If you tried to multiply [A] by [C], your TI-82 would signal an error
because the dimensions of the two matrices do not permit multiplication this way.
The transpose of a matrix [A] is another matrix with the rows and columns interchanged. The symbol for the
T
transpose of [A] is [A] . To calculate [A]
2.6.3 Row Operations: Here are the keystrokes necessary to perform elementary row operations on a matrix. Your
textbook provides more careful explanation of the elementary row operations and their uses.
To interchange the second and third rows of the matrix [A] that was defined above, press MATRX ► 8 MATRX 1 ,
2 , 3 ) ENTER (see Figure 2.65). The format of this command is rowSwap(matrix, row1, row2).
To add row 2 and row 3 and store the results in row 3, press MATRX ► 9 MATRX 1 , 2 , 3) ENTER. The format
of this command is row+(matrix, row1, row2).
To multiply row 2 by –4 and store the results in row 2, thereby replacing row 2 with new values, press MATRX ► 0
(-) 4, MATRX 1 , 2) ENTER. The format of this command is *row(scalar, matrix, row).
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G T
RAPHING ECHNOLOGY
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, press MATRX 1 MATRX ► 2 ENTER.
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G : TI-82
UIDE
Figure 2.64: Matrix [B]
 2 0 3 
. For matrix multiplication of [C]
 
− −
1 5 1
 