An effective three-step method to solve nonlinear equations

In this paper, we suggest a seventh order convergence three-step method to solve system of nonlinear equations. Every iteration of the method requires three function evaluations, two first Fréchet derivative evaluations and two matrix inversions. Hence, the efficiency index is $7^{1/(3n+6n^2+{4\over 3}n^3)$, which is better than that of other three-step methods