HP HP-15C - Miscellaneous Operations Involving Matrices; Using a Matrix Element With Register Operations; Using Matrix Descriptors in the Index Register

Section 12: Calculating with Matrices 173
A problem using this procedure is given in the HP-15C Advanced Functions
Handbook under Solving a Large System of Complex Equations.
Miscellaneous Operations Involving Matrices
Using a Matrix Element With Register Operations
If a letter key specifying a matrix is pressed after any of the following
function keys, the operation is performed using the matrix element specified
by the row and column numbers in R
0
and R
1
, just as though it were a data
storage register.
O
*
l
*
O{+, -, *, ÷}
l{+, -, *,
÷}
e
I
X
Using Matrix Descriptors in the Index Register
In certain applications, you may want to perform a programmed sequence
of matrix operations using any of the matrices A through E. In this
situation, the matrix operations can refer to whatever matrix descriptor is
stored in the index register (R
I
).
If the Index register contains a matrix descriptor:
 Pressing % after any of the functions listed above performs the
operations using the element specified by R
0
and R
1
and the matrix
specified in R
I
.

Pressing % after O| or l| performs the operation
using the element specified by the row and column numbers in the
Y- and X-registers and the matrix specified in R
I.
*
Also, in User mode the row and column numbers in R
0
and R
1
are incremented according to the
dimensions of the specified matrix.