roots function algorithm basis

Dear Community,

I am trying to understand how works root(P), being P a polynomial. As far as I know, MATLAB uses the companion matrix of P and after it uses QR factorization to get the roots. However, I do not know which QR factorization method it uses. Is it householder QR method?

Thanks so much for your help,

Estanis

Answer 1

[Neil Guertin]

According to the documentation, "The roots of the polynomial are calculated by computing the eigenvalues of the companion matrix". Eigenvalues are calculated using LAPACK functions.