FAQ

What coefficient order do functions expect?

Low-to-high (a0, a1, ..., aN) for polynomial a0 + a1 x + ... + aN x^N = 0.

How do I choose a method?

• hybrid is a good default (series seeds + Aberth finisher).
• aberth for simultaneous refinement.
• dk for robust derivative-free finishing.
• numpy if you prefer companion eigenvalues (requires NumPy).

When should I use resummation?

If the local parameter |t| = |-a0/a1| is not small, use resum="auto" (tries Padé/Borel–Padé).

What about multiple or clustered roots?

They are ill-conditioned. We add adaptive damping in Aberth and multiplicity-aware Halley polish, but residuals may still be sensitive.

Does SymPy need to be installed?

Only for the sympy_plugin. Core solvers work with Python complex numbers.

Are eigenvalues supported?

Yes, via solve_eigs(A) (Faddeev–LeVerrier + solver polish).