The structured distance to normality of an irreducible real tridiagonal matrix.
Silvia Noschese, Lionello Pasquini, Lothar Reichel · IRIS Research product catalog (Sapienza University of Rome) · 2007
The problem of computing the distance in the Frobenius norm of a given real irreducible tridiagonal matrix T to the algebraic variety of real normal irreducible tridiagonal matrices is solved. Simple formulas for computing the distance and a normal tridiagonal matrix at this distance are presented. The special case of tridiagonal Toeplitz matrices also is considered.