This example computes all the eigenvalues of the matrix $A$, where and those eigenvectors which correspond to eigenvalues $\lambda$ such that $\mathrm{Re}\left(\lambda \right)<0$. Here $A$ is general and must first be reduced to upper Hessenberg form $H$ by dgehrd. The program then calls dhseqr to compute the eigenvalues, and dhsein to compute the required eigenvectors of $H$ by inverse iteration. Finally dormhr is called to transform the eigenvectors of $H$ back to eigenvectors of the original matrix $A$.