Block algorithms for reordering a selected set of eigenvalues in a standard or generalized Schur form are proposed. Efficiency is achieved by delaying orthogonal transformations and (optionally) making use of level 3 BLAS operations. Numerical experiments demonstrate that existing algorithms, as currently implemented in LAPACK, are outperformed by up to a factor of four.
Daniel Kressner, Meiyue Shao, Yuxin Ma
Daniel Kressner, Ivana Sain Glibic
Daniel Kressner, Zvonimir Bujanovic