On the calculation of the multiplicity of a real eigenvalue of Hessenberg matrix
In this article, we describe three algorithms: the first one is used to compute the multiplicity of a real eigenvalue of a Hessenberg matrix A? nn in o(n3); the second for the computation of the determinant of a Hessenberg matrix in o(n2) and the third for the computation of the multiplicity of a real root of a polynomial in o(n2). It is a new matricial form and represents generalized Horner scheme.
hessenberg matrix algorithm multiplcity