Compute the roots of a general nth-degree polynomial

A = [ ];

a = compan(A);

e = eig(a);

I am trying to find the roots of a general polynomial of degree n using the eigenvalues of the companion matrix. What statement should I use next？

[Walter Roberson]

If you are trying to find numeric roots then why not use roots()?

Answer 1

[Sam Chak]

Hi @Jiapeng

The following article shows you a few methods to find the roots of a polynomial.

https://www.mathworks.com/help/matlab/math/roots-of-polynomials.html

A = 1:2:7

A = 1×4

1 3 5 7

a = compan(A)

a = 3×3

-3 -5 -7 1 0 0 0 1 0

eig(a)

ans = 
  -2.1795 + 0.0000i
  -0.4102 + 1.7445i
  -0.4102 - 1.7445i

roots(A)

ans = 
  -2.1795 + 0.0000i
  -0.4102 + 1.7445i
  -0.4102 - 1.7445i