Two-step Newton methods

We present sufficient convergence conditions for two-step Newton methods in order to approximate a locally unique solution of a nonlinear equation in a Banach space setting. The advantages of our approach over other studies such as Argyros et al. (2010) 5], Chen et al. (2010) 11], Ezquerro et al. (2000) 16], Ezquerro et al. (2009) 15], Hernández and Romero (2005) 18], Kantorovich and Akilov (1982) 19], Parida and Gupta (2007) 21], Potra (1982) 23], Proinov (2010) 25], Traub (1964) 26] for the semilocal convergence case are: weaker sufficient convergence conditions, more precise error bounds on the distances involved and at least as precise information on the location of the solution. In the local convergence case more precise error estimates are presented. These advantages are obtained under the same computational cost as in the earlier stated studies. Numerical examples involving Hammerstein nonlinear integral equations where the older convergence conditions are not satisfied but the new conditions are satisfied are also presented in this study for the semilocal convergence case. In the local case, numerical examples and a larger convergence ball are obtained.