Function halley 

pub fn halley<T: RealScalar>(
    poly: &Poly<T>,
    epsilon: T,
    max_iter: Option<usize>,
    initial_guess: Option<Complex<T>>,
) -> Result<(Vec<Complex<T>>, u128), Error<Vec<Complex<T>>>>

Find a single root

Returns

• vector of roots (usually 1)
• number of evaluations

Errors

• NoConverge: the root finder did not converge within the given constraints. The best guess so far is returned with the error.\n

Panics

If T is any primitive type, this function does not panic. However, if T does not implement num::FromPrimitive::from_f64 correctly, this function might panic under certain circumstances (casting of extreme values, usually)\n\n If T is f32 or f64, this function does not panic. However, if T cannot represent all primitive integers smaller than usize::MAX, this might panic under certain circumstances (casting of extreme values, usually)\n\n