HP -15C Advanced Functions Handbook page 155

Section 4: Using Matrix Operations 153
Keystrokes
IRCL || MATRIX |[B"|
[TJ [RESULT] [A]
s
Display
074-45,16,12
075-42,26,11
076- 20
077- 22 1 1
Calculates A - B
T
AB.
Labels used: A, 0, 1, 2, and 3.
Registers used: R
0
, Rj, R2 (off-diagonal sum), and R
3
Matrices used: A (A/), B (Q
;
), and C.
To use the program:
1. Press 4 [TJ|DIM |full to reserve registers R
0
through R
4
.
2. Press | T 1| USER |to activate User mode.
3. Dimension and enter the elements of matrix A using |T|[
P|M
I
fA~l and |STO| fA~l. The dimensions can be up to 4 X 4, provided
that there is sufficient memory available for matrices B and
C having the same dimensions also.
4. Press [A] to calculate and display the off-diagonal ratio.
5. Press | R/S| repeatedly until the displayed ratio is negligible,
say less than 10~
8
.
6. Press | RCL|fA~1 repeatedly to observe the elements of matrix A.
The diagonal elements are the eigenvalues.
Example: What quadratic surface is described by the equation
below?
x
2
x
3
]
0 1 2
1 2 3
2 3 4
= 7
Keystrokes Display
4.0000
4.0000
Run mode.
Allocates memory.
Activates User mode.