HP 40gs - Manual (Page 322)

18-8 Matrices
To divide by a
square 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
equivalent to M2
–1 * M1.
To divide the two matrices M1 and M2 that you created
for the previous example, press the following keys:
M1
M2
To invert a matrix You can invert a square matrix in HOME by typing the
matrix (or its variable name) and pressing
x –1
. Or you can use the matrix INVERSE command.
Enter INVERSE(matrixname) in HOME and press
.
To negate each
element You can change the sign of each element in a matrix by
pressing
before the matrix name.
Solving systems of linear equations
Example Solve the following linear system:
1. Open the Matrix
catalog and create a
vector.
MATRIX
2. Create the vector of the
constants in the linear
system.
5 7
1
2x 3y 4z + + 5
x y z – + 7
4x y – 2z + 1
=
=
=
hp40g+.book Page 8 Friday, December 9, 2005 1:03 AM