JOURNAL OF MATHEMATICAL CHEMISTRY, cilt.49, sa.2, ss.609-617, 2011 (SCI-Expanded, Scopus)
In this paper, we are concerned with a 3 x 3 complex matrix Jacobi (tri-diagonal matrix) arised from a non-Hermitian discrete quantum system. Necessary and sufficient conditions for reality of the eigenvalues of the matrix in question are established.