This work is supported by the Natural Science Foundation of Fujian Province of China (No. Z0511010);the Natural Science Foundation of China (No. 10571012).
Let H∈Cn×n be an n×n unitary upper Hessenberg matrix whose subdiagonal elements are all positive. Partition H as H=[H11 H12 H21 H22],(0.1) where H11 is its k×k leading principal submatrix; H22 is the complementary...