  We consider the vector space of $n \times n$ matrices over $\mathbb C$, Fermi
operators and operators constructed from these matrices and Fermi operators.
The properties of these operators are studied with respect to the underlying
matrices. The commutators, anticommutators, and the eigenvalue problem of such
operators are also discussed. Other matrix functions such as the exponential
functions are studied. Density operators and Kraus operators are also
discussed.
