### Finding complex roots

So, what is the best way to find complex roots of polynomials?

I only found that one:

```
sage: from sage.rings.polynomial.complex_roots import complex_roots
sage: x=polygen(ZZ)
sage: complex_roots(1.3*x^3-x^2-5*x-1)
[(-1.479272103982880?, 1), (-0.2113935621844148?, 1),
(2.459896435398064?, 1)]
```

Should I use that? Isn't there an inbuilt function? Even PARI/GP has one, namely `polroots`

...

And why is the `x`

casted as an element of ~~$\mathbb{Z}$, ~~$\mathbb{Z}[X]$, why not ~~$\mathbb{C}$? ~~$\mathbb{C}[X]$? Can somebody explain that to me?

Thank you!