Abstract

CALDERON, Wilson Rodríguez  and  PALLARES-MUNOZ, Myriam Rocío. Formulations to overcome the divergence of iterative method of fixed-point in nonlinear equations solution. Tecnura [online]. 2015, vol.19, n.44, pp.191-199. ISSN 0123-921X.  https://doi.org/10.14483/udistrital.jour.tecnura.2015.2.a14.

When we need to determine the solution of a nonlinear equation there are two options: closed-methods which use intervals that contain the root and during the iterative process reduce the size of natural way, and, open-methods that represent an attractive option as they do not require an initial interval enclosure. In general, we know open-methods are more efficient computationally though they do not always converge. In this paper we are presenting a divergence case analysis when we use the method of fixed point iteration to find the normal height in a rectangular channel using the Manning equation. To solve this problem, we propose applying two strategies (developed by authors) that allow to modifying the iteration function making additional formulations of the traditional method and its convergence theorem. Although Manning equation is solved with other methods like Newton when we use the iteration method of fixed-point an interesting divergence situation is presented which can be solved with a convergence higher than quadratic over the initial iterations. The proposed strategies have been tested in two cases; a study of divergence of square root of real numbers was made previously by authors for testing. Results in both cases have been successful. We present comparisons because are important for seeing the advantage of proposed strategies versus the most representative open-methods.

Keywords : divergence; fixed point; linear convergence; open methods; quadratic convergence; root equations.

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