A Family of Optimal Derivative Free Iterative Methods with Eighth-Order Convergence for Solving Nonlinear Equations

In this paper, modification of steffensen’s method with eight-order convergence is presented. we propose a family of optimal three-step methods with eight-order convergence for solving the simple roots of nonlinear equations by using the weight function and interpolation methods. per iteration this method requires four evaluations of the function which implies that the efficiency index of the developed methods is 1.682. some numerical examples illustrate that the algorithm is more efficient and performs better than other methods.