CHARLES R. JOHNSON, Ph.D.

Class of 1961 Professor

Department of Mathematics

(757) 221-2014

crjohnso@math.wm.edu

Charles Johnson works primarily in matrix analysis, linear algebra, and discrete mathematics. Within these areas his interests include topics motivated by the many applications that matrix analysis enjoys in the sciences.

Accordingly, Johnson researches combinatorial matrix theory, including matrix completion problems and qualitative matrix theory, inequalilities for generalized matrix functions, norms, numerical ranges, eigenvalues, and non-negative matrices. Qualitative matrix theory, for example, is motivated by problems in biology, chemistry, and economics in which qualitative information about model parameters is known from theory, while precise quantitative information is difficult to obtain.