hp 49g+_user's guide_English_E_DCVL5300427_V2

Page 11-5
The product of a vector with a matrix is possible if the vector is a row vector,
i.e., a 1×m matrix, which multiplied with a matrix m×n produces a 1xn matrix
(another row vector). For the calculator to identify a row vector, you must use
double brackets to enter it, e.g.,
Term-by-term multiplication
Term-by-term multiplication of two matrices of the same dimensions is possible
through the use of function HADAMARD. The result is, of course, another
matrix of the same dimensions. This function is available through Function
catalog (‚N), or through the MATRICES/OPERATIONS sub-menu
(„Ø). Applications of function HADAMARD are presented next:
The identity matrix
In Chapter 9 we introduce the identity matrix as the matrix I = [δ
ij
]
n
×
n
, where δ
ij
is the Kronecker’s delta function. Identity matrices can be obtained by using
function IDN described in Chapter 9. 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: