The Identity Matrix; The Inverse Matrix - HP 48gII User Manual

The identity matrix

The identity matrix has the property that A⋅I = I⋅A = A. To verify this property
we present the following examples using the matrices stored earlier on. Use
function IDN (find it in the MTH/MATRIX/MAKE menu) to generate the
identity matrix as shown here:

The inverse matrix

-1 -1 -1 ⋅A = I,
The inverse of a square matrix A is the matrix A such that A⋅A = A
where I is the identity matrix of the same dimensions as A. The inverse of a
matrix is obtained in the calculator by using the inverse function, INV (i.e., the
Y key). Examples of the inverse of some of the matrices stored earlier are
presented next:
To verify the properties of the inverse matrix, we present the following
multiplications:
Page 9-6