A Note on the “Constructing” of Nonstationary Methods for Solving Nonlinear Equations with Raised Speed of Convergence

This paper is partially supported by project ISM-4 of Department for Scientific Research, “Paisii Hilendarski” University of Plovdiv.In this paper we give methodological survey of “contemporary methods” for solving the nonlinear equation f(x) = 0. The reason for this review is that many authors in present days rediscovered such classical methods. Here we develop one methodological schema for constructing nonstationary methods with a preliminary chosen speed of convergence

Modifikasi metode Schroder tanpa turunan kedua dengan orde konvergensi empat

Metode Schroder merupakan metode iterasi berode dua yang digunakan untuk menentukan akar-akar persamaan nonlinear. Artikel ini membahas modifikasi metode Schroder untuk meningkatkan orde konvergensi. Metode Schroder dengan satu parameter real dikembangkan menggunakan ekspansi deret Taylor orde dua. Metode Schroder yang dimodifikasi masih memuat turunan kedua. Selanjutnya, turunan kedua tersebut direduksi menggunakan kesamaan dua metode iterasi. Berdasarkan hasil kajian, metode iterasi baru mempunyai orde konvergensi empat yang melibatkan tiga evaluasi fungsi dengan indeks efisiensi sebesar  untuk b = ½. Simulasi numerik diberikan untuk menguji performa metode iterasi baru yang meliputi jumlah iterasi, orde konvergensi secara komputasi (COC), galat mutlak dan galat relatif. Nilai-nilai performa dari metode iterasi baru dibandingkan dengan metode Newton, metode Schroder, metode Chebyshev dan metode Halley. Hasil simulasi numerik menunjukkan bahwa performa metode iterasi baru lebih baik dibandingkan dengan metode iterasi lainnya

Two New Predictor-Corrector Iterative Methods with Third- and Ninth-Order Convergence for Solving Nonlinear Equations

In this paper, we suggest and analyze two new predictor-corrector iterative methods with third and ninth-order convergence for solving nonlinear equations. The first method is a development of [M. A. Noor, K. I. Noor and K. Aftab, Some New Iterative Methods for Solving Nonlinear Equations, World Applied Science Journal, 20(6),(2012):870-874.] based on the trapezoidal integration rule and the centroid mean. The second method is an improvement of the first new proposed method by using the technique of updating the solution. The order of convergence and corresponding error equations of new proposed methods are proved. Several numerical examples are given to illustrate the efficiency and performance of these new methods and compared them with the Newton's method and other relevant iterative methods. Keywords: Nonlinear equations, Predictor–corrector methods, Trapezoidal integral rule, Centroid mean, Technique of updating the solution; Order of convergence

Modelado matemático y simulación numérica de disipadores de calor para luminarias LED. Aplicaciones a alumbrado público

[ES] En esta tesis se plasma un ejemplo paradigmático de Matemática Industrial: se define un problema real de enorme interés actual, se presenta un modelo matemático del mismo, se resuelve numéricamente mediante métodos de elementos Finitos, se realiza diferentes prototipos y se verifican experimentalmente las predicciones teóricas; además, en este caso particular, los prototipos aquí analizados se llevaron al mercado, cerrando un ciclo que se inicia con el modelado matemático y se termina con la transferencia a la sociedad de una solución competitiva a un problema real. El problema que se aborda en esta tesis se enmarca en el desarrollo de soluciones de iluminación basadas en tecnología de diodos emisores de luz (LED, por su abreviación en inglés) de alta potencia. De hecho, el problema que se afronta es el desarrollo de disipadores pasivos de calor que garanticen la correcta evacuación del calor producido en el dispositivo LED y aseguren su adecuado funcionamiento. Para ello, se modela el problema de transferencia de calor (incluyendo conducción, radiación y convección) en diferentes prototipos, se resuelve con técnicas de Elementos Finitos y se optimizan los diseños propuestos, garantizando siempre que la temperatura de operación del chip LED sea correcta. Una vez realizado este análisis teórico, se construyen los prototipos y se verifican experimentalmente las predicciones realizadas. Por último, en los anexos se recoge una serie de aportaciones complementarias: una sobre el gas de van der Waals y la Geometría de Contacto y otras dos sobre la convergencia de métodos iterativos.[CA] En aquesta tesi es plasma un exemple paradigmàtic de Matemàtica Industrial: es defineix un problema real d'enorme interès actual, es presenta un model matemàtic del mateix, es resol numèricament mitjançant mètodes d'Elements Finits, es realitza diferents prototips i es verifiquen experimentalment les prediccions teòriques; a més, en aquest cas particular, els prototips aquí analitzats es van dur a mercat, tancant un cicle que s'inicia amb el modelatge matemàtic i s'acaba amb la transferència a la societat d'una solució competitiva a un problema real. El problema que s'aborda en aquesta tesi s'emmarca en el desenvolupament de solucions d'il·luminació basades en tecnologia LED d'alta potència. De fet, el problema que s'afronta és el desenvolupament de dissipadors passius de calor que garanteixin la correcta evacuació de la calor produïda da en el dispositiu LED i assegurin la seva adequat funcionament. Per a això, es modela el problema de transferència de calor (incloent conducció, radiació i convecció) en diferents prototips, es resol amb tècniques d'Elements Finits i s'optimitzen els dissenys proposats, garantint sempre que la temperatura d'operació de l'xip LED sigui correcta. Un cop realitzat aquest anàlisi teòrica, es construeixen els prototips i es verifiquen experimentalment les prediccions realitzades. Finalment, en els annexos es recull una sèrie d'aportacions complementàries: una sobre el gas de van der Waals i la Geometria de Contacte i dues sobre la convergència de mètodes iteratius.[EN] In this thesis, a paradigmatic example of Industrial Mathematics is captured: a real problem of enormous current interest is defined, a mathematical model of it is presented, it is solved numerically using Finite Element methods, different prototypes are made and the theoretical predictions are experimentally verified; Furthermore, in this particular case, the prototypes analyzed here were brought to the market, closing a cycle that begins with mathematical modeling and ends with the transfer to society of a competitive solution to a real problem. The problem addressed in this thesis is part of the development of lighting solutions based on high-power LED technology. In fact, the problem being faced is the development of passive heat sinks that guarantee the correct evacuation of the heat produced in the LED device and ensure its proper operation. For this, the heat transfer problem (including conduction, radiation and convection) is modeled in different prototypes, it is solved with Finite Element techniques and the proposed designs are optimized, always guaranteeing that the operating temperature of the LED chip is correct. Once this theoretical analysis has been carried out, the prototypes are built and the predictions made are experimentally verified. Finally, the annexes contain a series of complementary contributions: one on van der Waals gas and Contact Geometry and two others on the convergence of iterative methods.A la Secretarıa de Educación Superior, Ciencia,Tecnología e Innovación (SENESCYT) por el apoyo económico para poder realizar mis estudios en el extranjero con el fin de fortalecer el talento humano en el Ecuador.Alarcón Correa, DF. (2020). Modelado matemático y simulación numérica de disipadores de calor para luminarias LED. Aplicaciones a alumbrado público [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/155989TESI

Dynamics of Newton-like root finding methods

Altres ajuts: project UJI-B2019-18When exploring the literature, it can be observed that the operator obtained when applying Newton-like root finding algorithms to the quadratic polynomials z − c has the same form regardless of which algorithm has been used. In this paper, we justify why this expression is obtained. This is done by studying the symmetries of the operators obtained after applying Newton-like algorithms to a family of degree d polynomials p(z) = z − c. Moreover, we provide an iterative procedure to obtain the expression of new Newton-like algorithms. We also carry out a dynamical study of the given generic operator and provide general conclusions of this type of methods

Dynamics of Newton-like root finding methods

When exploring the literature, it can be observed that the operator obtained when applying Newton-like root finding algorithms to the quadratic polynomials z2 − c has the same form regardless of which algorithm has been used. In this paper, we justify why this expression is obtained. This is done by studying the symmetries of the operators obtained after applying Newton-like algorithms to a family of degree d polynomials p(z) = zd −c. Moreover, we provide an iterative procedure to obtain the expression of new Newton-like algorithms. We also carry out a dynamical study of the given generic operator and provide general conclusions of this type of methods.Funding for open access charge: CRUE-Universitat Jaume

On Some Optimal Multiple Root-Finding Methods and their Dynamics

Finding multiple zeros of nonlinear functions pose many difficulties for many of the iterative methods. In this paper, we present an improved optimal class of higher-order methods for multiple roots having quartic convergence. The present approach of deriving an optimal class is based on weight function approach. In terms of computational cost, all the proposed methods require three functional evaluations per full iteration, so that their efficiency indices are 1.587 and, are optimal in the sense of Kung-Traub conjecture. It is found by way of illustrations that they are useful in high precision computing enviroments. Moreover, basins of attraction of some of the higher-order methods in the complex plane are also given

Family of Multiple-Root Finding Iterative Methods Based on Weight Functions

A straightforward family of one-point multiple-root iterative methods is introduced. The family is generated using the technique of weight functions. The order of convergence of the family is determined in its convergence analysis, which shows the constraints that the weight function must satisfy to achieve order three. In this sense, a family of iterative methods can be obtained with a suitable design of the weight function. That is, an iterative algorithm that depends on one or more parameters is designed. This family of iterative methods, starting with proper initial estimations, generates a sequence of approximations to the solution of a problem. A dynamical analysis is also included in the manuscript to study the long-term behavior of the family depending on the parameter value and the initial guess considered. This analysis reveals the good properties of the family for a wide range of values of the parameter. In addition, a numerical test on academic and engineering multiple-root functions is performed

Some Multiple and Simple Real Root Finding Methods

Solving nonlinear equations with root finding is very common in science and engineering models. In particular, one applies it in mathematics, physics, electrical engineering and mechanical engineering. It is a researchable area in numerical analysis. This present work focuses on some iterative methods of higher order for multiple roots. New and existing novel multiple and simple root finding techniques are discussed. Methods independent of a multiplicity m of a root r, which function very well for both simple and multiple roots, are also presented. Error-correction and variatonal technique with some function estimations are used for the constructions. For the analysis of orders of convergence, some basic theorems are applied. Ample test examples are provided (in C++) for test of efficiencies with suitable initial guesses. And convergence of some methods to a root is shown graphically using matlab applications. Keywords:Iterative algorithms, error-correction, variational methods, multiple roots, applications