HP 15c - Manual (Page 141)

Section 4: Using Matrix Operations 141
Labels used: A, B, and 2 through 8.
Registers used: R
2
through R
9
, R
.0
, R
.1
, and Index register.
Matrices used: A, B, C, D, and E.
Your subroutine, labeled "E", may use any labels and registers not listed above, plus the
Index register, matrix B, and matrix E (which should contain your calculated gradient).
To use the program:
1. Enter your subroutine into program memory.
2. Press 11 ´m% to reserve registers R
0
through R
.1
(Your subroutine may
require additional registers.)
3. Set flag 0 if you're seeking a local minimum; clear flag 0 if you're seeking a local
maximum.
4. Dimension matrix A to n×1, where n is the number of variables.
5. Store the required data in memory:

Store the I nitial estimate x
0
in matrix A.

Store a in R
2
.

Store e in R
3
.

Store d in R
4
.

Store N in R
5
.
6. Press GA to view the slopes during the iteration procedure.

View the iteration number and the value of f(x).

If Error 1 appears, press − to clear the message. Then either go back to step and
possibly revise parameters as needed, or press −¦ to provide one more
bounding search iteration or one more optimization iteration. (If the descriptor of
matrix A was in the display when the error occurred, the number of bounding
search iterations exceeded N; if the descriptor of matrix C was in the display, the
number of optimization iterations exceeded N.)
7. Press ¦ to view the norm of the gradient and to start the next iteration.

If the display flashes the norm of the gradient, press − and then recall the values
of x in matrix A.

If the iteration number and value of f(x) are displayed, repeat this step as often as
necessary to obtain the solution or go back to step 5 and revise parameters as
needed.