HP 39G User Manual page 179

To multiply two
matrices
To divide by a
square matrix
To invert a matrix
To negate each
element
Matrices
To multiply the two matrices M1 and M2 that you created for
the previous example, use the following keystrokes:
M1 M2
To multiply a matrix by a vector, enter the matrix first, then
the vector. The number of elements in the vector must equal
the number of columns in the matrix.
For division of a matrix or a vector by a square matrix, the
number of rows of the dividend (or the number of elements, if
it is a vector) must equal the number of rows in the divisor.
This operation is not a mathematical division: it is a left–
multiplication by the inverse of the divisor. M1/M2 is
–1
equivalent to M2 * M1.
To divide the two matrices M1 and M2 that you created for the
previous example, use the following keystrokes:
M1 M2
You can invert a square matrix in HOME by typing the matrix
(or its variable name) and pressing
can use the matrix INVERSE command. Enter
INVERSE(matrixname) in HOME and press
You can change the sign of each element in a matrix by
pressing before the matrix name.
–1
x . Or you
.
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