New modifications of Newton-type methods with eighthorder convergence for solving nonlinear equations

The aims of this paper are, firstly, to define a new family of the Thukral and Petkovic type methods for finding zeros of nonlinear equations and secondly, to introduce new formulas for approximating the order of convergence of the iterative method. It is proved that these methods have the convergence order of eight requiring only four function evaluations per iteration. In fact, the optimal order of convergence which supports the Kung and Traub conjecture have been obtained. Kung and Traub conjectured that the multipoint iteration methods, without memory based on n evaluations, could achieve optimal convergence order 2n-1.  Thus, new iterative methods which agree with the Kung and Traub conjecture for n = 4  have been presented. It is observed that our proposed methods are competitive with other similar robust methods and very effective in high precision computations

Solving Polynomial Equations using Modified Super Ostrowski Homotopy Continuation Method

Homotopy continuation methods (HCMs) are now widely used to find the roots of polynomial equations as well as transcendental equations.  HCM can be used to solve the divergence problem as well as starting value problem. Obviously, the divergence problem of traditional methods occurs when a method cannot be operated at the beginning of iteration for some points, known as bad initial guesses. Meanwhile, the starting value problem occurs when the initial guess is far away from the exact solutions.   The starting value problem has been solved using Super Ostrowski homotopy continuation method for the initial guesses between . Nevertheless, Super Ostrowski homotopy continuation method was only used to find out real roots of nonlinear equations.  In this paper, we employ the Modified Super Ostrowski-HCM to solve several real life applications which involves polynomial equations by expanding the range of starting values. The results indicate that the Modified Super Ostrowski-HCM performs better than the standard Super Ostrowski-HCM. In other words, the complex roots of polynomial equations can be found even the starting value is real with this proposed scheme

Steffensen type methods for solving nonlinear equations

[EN] In the present paper, by approximating the derivatives in the well known fourth-order Ostrowski's method and in a sixth-order improved Ostrowski's method by central-difference quotients, we obtain new modifications of these methods free from derivatives. We prove the important fact that the methods obtained preserve their convergence orders 4 and 6, respectively, without calculating any derivatives. Finally, numerical tests confirm the theoretical results and allow us to compare these variants with the corresponding methods that make use of derivatives and with the classical Newton's method. (C) 2010 Elsevier B.V. All rights reserved.This research was supported by Ministerio de Ciencia y Tecnología MTM2010-18539Cordero Barbero, A.; Hueso Pagoaga, JL.; Martínez Molada, E.; Torregrosa Sánchez, JR. (2012). Steffensen type methods for solving nonlinear equations. Journal of Computational and Applied Mathematics. 236(12):3058-3064. https://doi.org/10.1016/j.cam.2010.08.043S305830642361

Three-step iterative methods with optimal eighth-order convergence

In this paper, based on Ostrowski's method, a new family of eighth-order methods for solving nonlinear equations is derived. In terms of computational cost, each iteration of these methods requires three evaluations of the function and one evaluation of its first derivative, so that their efficiency indices are 1.682, which is optimal according to Kung and Traub's conjecture. Numerical comparisons are made to show the performance of the new family. © 2011 Elsevier B.V. All rights reserved.This research was supported by Ministerio de Ciencia y Tecnologia MTM2010-18539.Cordero Barbero, A.; Torregrosa Sánchez, JR.; Penkova Vassileva, M. (2011). Three-step iterative methods with optimal eighth-order convergence. Journal of Computational and Applied Mathematics. 235(10):3189-3194. https://doi.org/10.1016/j.cam.2011.01.004S318931942351