Create a 3-by-3 matrix.

A = [1 0 1i; 0 1 0;-1i 0 1]

A = 3×3 complex

   1.0000 + 0.0000i   0.0000 + 0.0000i   0.0000 + 1.0000i
   0.0000 + 0.0000i   1.0000 + 0.0000i   0.0000 + 0.0000i
   0.0000 - 1.0000i   0.0000 + 0.0000i   1.0000 + 0.0000i

The matrix is Hermitian and has a real-valued diagonal.

Test whether the matrix is symmetric.

tf = issymmetric(A)

tf = logical
   0

The result is logical 0 (false) because A is not symmetric. In this case, A is equal to its complex conjugate transpose, A', but not its nonconjugate transpose, A.'.

Change the element in A(3,1) to be 1i.

A(3,1) = 1i;

Determine whether the modified matrix is symmetric.

tf = issymmetric(A)

tf = logical
   1

The matrix, A, is now symmetric because it is equal to its nonconjugate transpose, A.'.

Create a 4-by-4 matrix.

A = [0 1 -2 5; -1 0 3 -4; 2 -3 0 6; -5 4 -6 0]

A = 4×4

     0     1    -2     5
    -1     0     3    -4
     2    -3     0     6
    -5     4    -6     0

The matrix is real and has a diagonal of zeros.

Specify skewOption as 'skew' to determine whether the matrix is skew-symmetric.

tf = issymmetric(A,'skew')

tf = logical
   1

The matrix, A, is skew-symmetric since it is equal to the negation of its nonconjugate transpose, -A.'.