Date of Award
Doctor of Philosophy (PhD)
Mathematics and Statistics
Frank. J. Hall
In this work we discover for the first time a strong relationship between Geršgorin theory and the geometric multiplicities of eigenvalues. In fact, if λ is an eigenvalue of an n × n matrix A with geometric multiplicity k, then λ is in at least k Geršgorin discs of A. Moreover, construct the matrix C by replacing, in every row, the (k − 1) smallest off-diagonal entries in absolute value by 0, then λ is in at least k Geršgorin discs of C. We also state and prove many new applications and consequences of these results as well as we update an improve some important existing ones.
Marsli, Rachid, "New Extensions and Applications of Geršgorin Theory." Dissertation, Georgia State University, 2015.