Properties
- The eigenvalues of a skew-Hermitian matrix are all purely imaginary. Furthermore, skew-Hermitian matrices are normal. Hence they are diagonalizable and their eigenvectors for distinct eigenvalues must be orthogonal.
- All entries on the main diagonal of a skew-Hermitian matrix have to be pure imaginary, i.e., on the imaginary axis (the number zero is also considered purely imaginary).
- If A, B are skew-Hermitian, then aA + bB is skew-Hermitian for all real scalars a and b.
- If A is skew-Hermitian, then both iA and -iA are Hermitian.
- If A is skew-Hermitian, then Ak is Hermitian if k is an even integer and skew-Hermitian if k is an odd integer.
- An arbitrary (square) matrix C can uniquely be written as the sum of a Hermitian matrix A and a skew-Hermitian matrix B:
- If A is skew-Hermitian, then eA is unitary.
- The space of skew-Hermitian matrices forms the Lie algebra u(n) of the Lie group U(n).
Read more about this topic: Skew-Hermitian Matrix
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