HP 15c - Manual (Page 154)

154 Section 12: Calculating with Matrices
Keystrokes
Display
- C 2 3
Calculates B - A and stores
values in redimensioned result
matrix C.
The result is 






8 4 3
2 1 0
C
Matrix Multiplication
With matrix description in both the X- and Y-registers, you can calculate
three different matrix products. The table below shows the results of the
three functions for a matrix X specified in the X-register and a matrix Y
specified in the Y-register. The matrix X
-1
is the inverse of X, and the
matrix Y
T
is the transpose of Y.
Pressing Calculates*
*
YX
´ > 5
Y
T
X
÷
X
-1
Y
* Result is stored in result matrix. For
÷
, the
result matrix can be Y but not X. For the others,
the result matrix must be other than X or Y.
Note: When you use the ÷
function to evaluate the expression
A
-1
B, you must enter the matrix descriptors in the order B, A rather
than in the order that they appear in the expression.
*
The value stored in each element of the result matrix is determined
according to the usual rules of matrix multiplication.
For > 5, the matrix specified in the Y-register isn't changed by this
operation, even though its transpose is used. The result is identical to that
obtained using > 4 (transpose) and *.
*
This is the same order you would use if you were entering b and a for evaluating a
-1
b = b/a