Miguel Ángel Hernández Verón

In this study, we use a family of third-order iterative methods to locate, separate, and approximate a solution of non-linear integral equations of Hammerstein type. We will consider two situations, when the kernel of the integral equation is separable and when it is not separable. When the kernel is non-separable, we will approximate the given integral equation by means of a new one with a separable kernel, and this transformation allows us to locate and approximate a solution of the first integral equation. To apply our theoretical findings, various examples have been tested.

The main problem with the Newton method is the computation of the inverse of the first derivative of the operator involved at each iteration step. Thus, when we want to apply the Newton method directly to solve an integral equation, the existence of the inverse of the first derivative is guaranteed, when the kernel is sufficiently differentiable into any of its two components, through its approximation by Taylor’s polynomial. In this paper, we study the case in which the kernel is not differentiable in any of its two components. So, we present a strategy that consists of approximating the kernel of the nonlinear integral equation by a Chebyshev interpolation polynomial, which is separable. This allows us to explicitly calculate the inverse of the first derivative operator in each step of the Newton method and then approximate a solution of the approximate integral equation.

We present a new fixed point result in Banach spaces by using divided differences of first order and auxiliary points to obtain a result of the so-called restricted fixed point. In particular, we use the secant method to draw conclusions about the fixed point and the domain where it is located, so that we obtain global convergence of the secant method to approximate the fixed point with superlinear speed of convergence.

In this article, we consider two parametric classes of derivative free iterative methods of high order of convergence in Banach spaces. We study local and semilocal convergence results in Banach spaces for both families of iterative processes. We carry out a numerical application to solve a nonlinear and nondifferentiable Fredholm integral equation in the Banach space of continuous functions with the maximum norm.

It is known that the global convergence of the method of successive approximations is obtained by means of the Banach contraction principle. In this paper, we study the global convergence of the method by means of a technique that uses auxiliary points and, as a consequence of this study, we obtain fixed-point type results on closed balls. We apply the study to nonlinear Fredholm integral equations of the second kind.

In this paper, we present a new fixed-point result to draw conclusions about the existence and uniqueness of the solution for a nonlinear Fredholm integral equation of the second kind with non-differentiable Nemytskii operator. To do this, we will transform the problem of locating a fixed point for an integral operator into the problem of locating a solution of an integral equation. Thus, assuming conditions on the Nemytskii operator, we will obtain a global convergence domain for the solution of the considered integral equation, taking for this a uniparametric family of derivativefree iterative processes with quadratic convergence. This result provides us a new fixed-point result for the integral operator considered. Keyword : fixed point theorem, global convergence, Fredholm integral equations, derivative-free iterative processes