Computation of the field of values of a 2 x 2 matrix
Charles R. Johnson · Journal of Research of the National Bureau of Standards Section B Mathematical Sciences · 1974
It is kno wn that the field of values , F(A) '" {x* Ax: x*x= 1, X~C2} , of a 2 X 2 matrix A is a conve x set whose boundary is an e llipse.This is used to compute F(A ) ex pli c itly from th e e ntri es of A