This example computes all the eigenvalues of $Az=\lambda Bz$, where and Here $A$ is Hermitian, $B$ is Hermitian positive definite, and $A$ and $B$ are treated as band matrices. $B$ must first be factorized by zpbstf. The program calls zhbgst to reduce the problem to the standard form $Cy=\lambda y$, then zhbtrd to reduce $C$ to tridiagonal form, and dsterf to compute the eigenvalues.