HP HP-15C - Page 139

Section 12: Calculating with Matrices 139
Keystrokes
Display
| " 8
Deactivates Complex
mode.
2 v ´ m A
2.0000
Dimensions matrix A
to be 2×2.
´ > 1
2.0000
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 a
11
.
7.2 O A
7.2000
Stores a
12
.
1.3 O A
1.3000
Stores a
21
.
.9 “ O A
-0.9000
Stores a
22
.
2 v 1 ´ m
B
1.0000
Dimensions matrix B to
be 2×l.
16.5 O B
16.5000
Stores b
11
.
22.1 “ O B
-22.1000
Stores b
21
.
´ < C
-22.1000
Designates matrix C
for storing the result.
Using matrix notation, the solution of the matrix equation AX = B is
X = A
-1
B
where A
1
is the inverse of matrix A. You can perform this operation by
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.