LAPACK [12] presents a few error bounds for
computed eigenvectors of
the (small) dense GNHEP of a regular
matrix pair , assuming the availability of the generalized Schur
decomposition of the pair. Interested readers are referred
to [425,431]. It is generally not possible to
assess the accuracy of computed eigenvectors of the large sparse problems
with only partial information of a few eigenvalues and eigenvectors.