HP 15c - Manual (Page 149)

Section 12: Calculating with Matrices 149
While the key used for any matrix operation that stores a result in the result
matrix is held down, the descriptor of the result matrix is displayed. If the
key is released within about 3 seconds, the operation is performed, and the
descriptor of the result matrix is placed in the X-register. If the key is held
down longer, the operation is not performed and the calculator displays
null.
Copying a Matrix
To copy the elements of a matrix into the corresponding elements of
another matrix, use the O > sequence:
1. Press l > followed by the letter key specifying the
matrix to be copied. This enters the descriptor of the matrix into
the display.
2. Press O> followed by the letter key specifying the
matrix to be copied into.
If the matrix specified after l does not have the same dimensions as the
matrix specified after O, the second matrix is redimensioned to agree
with the first. The matrix specified after O need not already be
dimensioned.
Example: Copy matrix A from the previous example into matrix B.
Keystrokes Display
l>
A A 2 3 Displays descriptor of
matrix to be copied.
O>
B A 2 3
Redimensions matrix B and
copies A into B.
l>
B b 2 3
Displays descriptor of new
matrix B.
One-Matrix Operations
The following table shows functions that operate on only the matrix
specified in the X-register. Operations involving a single matrix plus a
number in another stack register are described under Scalar Operations
(page 151).