A note on the convergence rate of Kumar–Singh–Srivastava methods for solving nonlinear equations

Abstract

In the present article, it is shown that both the methods presented in Kumar et al. (2013) do not possess
the order of convergence as claimed. One of the two methods, derivative involved method possesses
the convergence rate of eighth order whereas the other derivative free method possesses sixth order
convergence. The theoretical convergence rate is also validated by computational order of convergence.