Multiplying complex matrices – HP 15c User Manual

Page 167

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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.

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