Corollary 2. Let A be a nonzero m2 × n2 real or complex matrix and suppose that
A = B ⊗ B for some m × n matrix B.
(a) A is symmetric if and only if B is either symmetric or skew symmetric.
(b) A is not skew symmetric.
(c) A is Hermitian if and only if B is either Hermitian or skew Hermitian.
(d) A is Hermitian positive definite if and only if B is Hermitian and definite (positive
or negative).
(e) A is skew Hermitian if and only if ei π/4B is Hermitian.
(f) A is unitary if and only if B is unitary.