Isolating a root of a polynomial

[Jeroen Demeyer <jdemeyer@cage.ugent.be>]

Hello pari-dev,

I am wondering if there is an algorithm (preferably implemented in PARI) 
which can isolate a complex root of a given polynomial?

The typical use case is that I have a polynomial for which I know one 
approximate root and I want to find a complex interval around that root 
which contains no other roots. The point is that I need to do this for 
just one root, not all roots of the given polynomial.

The input polynomial has exact (t_INT or t_FRAC) coefficients.

Cheers,
Jeroen.