Table 1 Mathematical notation

O _{M ×  N}

M × N matrix with all-zero entries

\( {\boldsymbol{i}}_M^{(l)} \)

M × 1 vector of zeros except for the l-th element, which has value 1

I _N

N dimensional identity matrix

⊗

Kronecker product

⊙

Schur product (element-by-element multiplication)

vecd[⋅]

Vector formed diagonal element of a matrix

tr{⋅}

Trace

diag{⋅}

Composition of the diagonal matrix

blkdiag{⋅}

Composition of the block diagonal matrix

‖ ⋅ ‖

Euclidean norm of a vector

a(i : j)

Subvector composed from the i-th to j-th elements

A(i : j, k : m)

Submatrix composed from the i-th to j-th row and k-th to m-th column of A

sgn(⋅)

Signum function