Section 12: Calculating with Matrices 139

Keystrokes

Display

" 8

Deactivates Complex

 

mode.

2 v ´ m A 2.0000

´ > 12.0000

Dimensions matrix A to be 2×2.

Prepares for automatic entry of matrix elements in User mode.

´ U

2.0000

 

(Turns on the USER

 

 

 

annunciator.)

3.8 O A

A

1,1

Denotes matrix A, row

 

 

 

1, column 1. (A display

 

 

 

like this appears

 

 

 

momentarily as you

 

 

 

enter each element and

 

 

 

remains as long as you

 

 

 

hold the letter key.)

 

3.8000

 

Stores a11.

7.2 O A

7.2000

 

Stores a12.

1.3 O A

1.3000

 

Stores a21.

.9 “ O A

-0.9000

 

Stores a22.

2 v 1 ´ m

1.0000

 

Dimensions matrix B to

B

 

 

be 2×l.

16.5 O B

16.5000

Stores b11.

22.1 “ O B

-22.1000

Stores b21.

´ < C

-22.1000

Designates matrix C

 

 

 

for storing the result.

Using matrix notation, the solution of the matrix equation AX = B is

X = A-1B

where A–1is the inverse of matrix A. You can perform this operation by entering the ―descriptors‖ for matrices B and A into the Y- and X-registers and then pressing ÷. (A descriptor shows the name and dimensions of a matrix.) Note that if A and B were numbers, you could calculate the answer in a similar manner.

Page 139
Image 139
HP 15c Scientific manual Keystrokes Display Deactivates Complex Mode, = A-1B