C++ program with MKL i have written a c++ example for Matrix eigenvalue/eigenvector problem. In the Documentation MKL all the examples are given in FORTRAN/C . To find all the eigenvalue and optionally all the eigenvector of real symmetric matrix i have used the lapack function dsyev from MKL . In This example i have created a matrix which correspond to 3D Tight Binding Hamiltonian. This is quit common in Condensed Matter Physics community.