A square matrix A is antihermitian if it satisfies A^H = - A, where A^H is the adjoint. For example, the matrix [i | 1 + i | 2i -1 + i | 5i | 3 2i | -3 | 0] is an antihermitian matrix. Antihermitian matrices are often called "skew Hermitian matrices" by mathematicians. A matrix m can be tested to see if it is antihermitian in the Wolfram Language using AntihermitianMatrixQ[m].