eigenvectors(...,Hermitian=>...)  Hermitian=>true means assume the matrix is symmetric or Hermitian
Synopsis

 Usage:
eigenvectors(M, Hermitian=>true)

Consequences:

The resulting matrix of eigenvalues is defined over RR, not CC, and, if the original matrix is defined over RR, the matrix of eigenvalues is too.
Further information

Default value: false

Function: eigenvectors  find eigenvectors of a matrix over RR or CC

Option key: Hermitian  an optional argument
Caveat
The internal routine uses a different algorithm, only considering the upper triangular elements. So if the matrix is not symmetric or Hermitian, the routine will give incorrect results.
Functions with optional argument named Hermitian :