HP HP-15C - Page 167

Section 12: Calculating with Matrices 167
8.
Press * to calculate X
P
= (YX)
P
. The values of these matrix
elements are placed in the result matrix, and the descriptor of
the result matrix is placed in the X-register.
9.
If you want the product in the form (YX)
C
, press |c
Note that you don't transform X
P
into 

.
You can derive the complex elements of the matrix product YX by recalling
the elements of (XY)
P
or (YX)
C
and combining them according to the
conventions described earlier.
Example: Calculate the product ZZ
-1
, where Z is the complex matrix given
in the preceding example.
Since elements representing both matrices are already stored (

in A and
(Z
-1
)
P
in B), skip steps 1, 3, 4, and 6.
Keystrokes
Display
l>A
A
4
4
Displays descriptor of matrix A.
l>B
b
4
2
Displays descriptor of matrix
B.
´<C
b
4
2
Designates C as result matrix.
*
C
4
2
Calculates 

(Z
-1
)
P
= (ZZ
-1
)
P
.
´U
C
4
2
Activates User mode.
lC
C
1,1
Matrix C, row 1, column 1.
(Displayed momentarily while
last key held down.)
1.0000
Value of c
11
.
lC
–2.8500 –10
Value of c
12
.
lC
–4.0000 –11
Value of c
21
.
lC
1.0000
Value of c
22
.
lC
1.0000 –11
Value of c
31
.
lC
3.8000 –10
Value of c
32
.
lC
1.0000 –11
Value of c
41
.
lC
–1.0500 –10
Value of c
42
.
´U
–1.0500 –10
Deactivates User mode.