Computer generated numerical ranges and some resulting theorems
Marvin D. Marcus, Claire Pesce · Linear and Multilinear Algebra · 1987
The numerical rangeW(A), of an arbitrary n-square matrix A is the union of the numerical ranges of all 2-square real compressions of A. As a result, a simple graphics program is written that accurately exhibits W(A) for real A, and suggests several conjectures relating the geometry of W(A) to algebraic properties of A. Some of these conjectures are analyzed in the final sections of the paper.