Suppose is a nonlinear equation where is an operator between two Banach spaces with continuous Fréchet derivative . The best known iterative method to solve approximatively the equation is the Newton method which has however two drawbacks: it requires the calculation of and the solution of a linear equation. In order to avoid these drawbacks which make the method of Newton inefficient from the point of view of calculation, several authors have introduced the iterative inexact methods.
The purpose of the paper is to give a convergence criterion for inexact procedures. As example the authors apply their results to a Hammerstein integral equation of the second kind:
where is continuous and positive on and is the Green’s function: