HP-15C
Matrix Operations
Memory A total of 64 matrix elements can be used in a total of 5 matrices
named A-E. Different matrices can have different size; sometimes
the result of a matrix operation can overwrite the input matrix.
The registers for the matrix elements are allocated from the
uncommitted registers space, see MEM.
See further down for complex matrices.
MATRIX 0 Redimensions all matrices to 0x0 thus freeing up all memory
occupied by matrices
Matrix descriptors The stack registers, Last-X and index register I as well as ordinary
storage registers can contain "
matrix descriptors
" which refer to one
of the matrices A-E. Ie. if there are two matrix descriptors in X and
Y then pressing "+" will add them and put the result in the
result
matrix.
Matrix descriptors can be moved around in the stack and
to/from storage registers like ordinary numbers
DIM A-E Dimensions one of the matrices A-E. It will have as many rows as
specified in Y and as many columns as specified in X.
Whan an existing matrix is redimensioned values are lost or zeros
inserted. Refer to pg. 142 of the Owner's Handbook
DIM (i) If I contains a matrix descriptor then the DIM operation will be
performed on the matrix specified in I.
This indirect method applies to other matrix operations, see below.
RCL DIM A-E, (i) Places the matrix' dimensions in X and Y. A non-exisiting matrix has
dimensions 0x0
RCL MATRIX A-E Put a matrix descriptor in the X register. This displays the matrix'
name and its dimensions
STO 0-9, .0-.9, I
RCL 0-9, .0-.9, I
Matrix descriptors can be stored in and recalled from ordinary
storage registers
MATRIX 1 Stores 1 in R0 and R1 which are used to index matrix elements.
Useful in preparation of matrix element input
STO A-E, (i)
RCL A-E, (i)
Store X in the matrix element of matrix A-E which is addressed by
registers R0 and R1. R0 is the row and R1 the column number,
starting from 1. RCL recalls the matrix element.
While the A-E key is held down, the matrix name, row and column
are displayed. R1 & R0 are automatically incremented in USER
mode, see below
USER When user mode is active, a STO A-E, (i) or RCL A-E, (i) operation
will automatically increment the column index in R1 until it wraps
back to 1 in which case the row index R0 is increment until it wraps
back to 1 as well.
So in user mode
all
matrix elements can quickly be entered and
recalled
STO +–x÷ A-E, (i)
RCL +–x÷ A-E, (i)
Matrix element arithmentic. Does not increment R1/R0 in USER
mode
7
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