@article{etna_vol3_pp83-95, author = {Richard S. Varga and Alan Krautstengl}, title = {Minimal Gerschgorin sets for partitioned matrices III. Sharpness of boundaries and monotonicity as a function of the partition}, journal = {Electron. Trans. Numer. Anal.}, volume = {3}, year = {1995}, pages = {83--95}, }