T. Lotfi - Department of Mathematics, Hamedan Branch, Islamic Azad University, Hamedan, ‎Iran‎.
P. Assari - Department of Mathematics, Hamedan Branch, Islamic Azad University, Hamedan, ‎Iran‎.

In this study, based on the optimal free derivative without memory methods proposed by Cordero et al. [A. Cordero, J.L. Hueso, E. Martinez, J.R. Torregrosa, Generating optimal derivative free iterative methods for nonlinear equations by using polynomial interpolation, Mathematical and Computer Modeling. ۵۷ (۲۰۱۳) ۱۹۵۰-۱۹۵۶], we develop two new iterative with memory methods for solving a nonlinear equation. The first has two steps with three self-accelerating parameters, and the second has three steps with four self-accelerating parameters. These parameters are calculated using information from the current and previous iteration so that the presented methods may be regarded as the with memory methods. The self-accelerating parameters are computed applying Newton's interpolatory polynomials. Moreover, they use three and four functional evaluations per iteration and corresponding R-orders of convergence are increased from ۴ ad ۸ to ۷.۵۳ and ۱۵.۵۱, respectively. It means that, without any new function calculations, we can improve convergence order by ۹۳\% and ۹۶\%.  We provide rigorous theories along with some numerical test problems to confirm theoretical results and high computational ‎efficiency.‎

Nonlinear equation, With memory method, R-order of convergence, Self accelerating parameter, Efficiency ‎index