HP 15c - Manual (Page 143)

Section 12: Calculating with Matrices 143
If you redimension a matrix to a larger size, elements with the value 0 are
added at the end as required by the new dimensions. For example, if the
same 2×3 matrix is re dimensioned, to 2×4, then
When you have finished calculating with matrices, you'll probably want to
redimension all five matrices to 0×0, so that the registers used for storing
their elements will be available for program lines or for other advanced
functions. You can redimension all five matrices to 0×0 at one time by
pressing ´ > 0. (You can dimension a single matrix to 0×0 by
pressing 0 ´ m {A through E}.)
Storing and Recalling Matrix Elements
The HP-15C provides two ways of storing and recalling values of matrix
elements. The first method allows you to progress through all of the
elements in order. The second method allows you to access elements
individually.
Storing and Recalling All Elements in Order
The HP-15C normally uses storage registers R
0
and
R
1
to indicate the row and column numbers of a
matrix element. If the calculator is in User mode,
the row and column numbers are automatically
incremented as you store or recall each matrix
element, from left to right along each row from the
first row to the last.
To set the row and column numbers in R
0
and R
1
to row 1, column 1,
press ´ > 1.