Convergence regions for the Chebyshev-Halley family

In this paper we study the dynamical behavior of the Chebyshev-Halley methods on the family of degree n polynomials z(n) + c. We prove that, despite increasing the degree, it is still possible to draw the parameter space by using the orbit of a single critical point. For the methods having z = infinity as an attracting fixed point, we show how the basins of attraction of the roots become smaller as the value of n grows. We also demonstrate that, although the convergence order of the Chebyshev-Halley family is 3, there is a member of order 4 for each value of n. In the case of quadratic polynomials, we bound the set of parameters which correspond to iterative methods with stable behaviour other than the basins of attraction of the roots. (C) 2017 Elsevier B.V. All rights reserved.