zhbgv example program

This example finds all the eigenvalues of the generalized band Hermitian eigenproblem

$A z = λ B z$ , where

$A = (\begin{array}{r} - 1.13 & 1.94 - 2.10 i & - 1.40 + 0.25 i & 0 \\ 1.94 + 2.10 i & - 1.91 & - 0.82 - 0.89 i & - 0.67 + 0.34 i \\ - 1.40 - 0.25 i & - 0.82 + 0.89 i & - 1.87 & - 1.10 - 0.16 i \\ 0 & - 0.67 - 0.34 i & - 1.10 + 0.16 i & 0.50 \end{array})$

and

$B = (\begin{array}{r} 9.89 & 1.08 - 1.73 i & 0 & 0 \\ 1.08 + 1.73 i & 1.69 & - 0.04 + 0.29 i & 0 \\ 0 & - 0.04 - 0.29 i & 2.65 & - 0.33 + 2.24 i \\ 0 & 0 & - 0.33 - 2.24 i & 2.17 \end{array}) .$

Example program for zhbgv