scholarly journals A globally convergent method for finding zeros of integer functions of finite order

2017 ◽  
pp. 115-128
Author(s):  
А.Н. Громов
Keyword(s):  
Finite Order ◽  
Logarithmic Derivative ◽  
Initial Point ◽  
Globally Convergent ◽  
Finite Set ◽  
Minimum Number ◽  
Convergent Method ◽  
Arbitrary Initial Point ◽  
Partial Fractions ◽  
Derivatives Of

Предложен метод отыскания нулей целых функций конечного порядка, который сходится к корню от произвольной начальной точки, т.е. является глобально сходящимся. Метод основан на представлении производных высшего порядка от логарифмической производной в виде суммы простейших дробей и сводит отыскание корня к выбору минимального числа из конечного множества. Даны оценки скорости сходимости. A method for finding zeros of integer functions of finite order is proposed. This method converges to a root starting from an arbitrary initial point and, hence, is globally convergent. The method is based on a representation of higher-order derivatives of the logarithmic derivative as a sum of partial fractions and reduces the finding of a root to the choice of the minimum number from a finite set. The rate of convergence is estimated.

scholarly journals On Koenig's theorem for integer functions of finite order

2020 ◽  
pp. 280-289
Author(s):  
А.Н. Громов
Keyword(s):  
Convergence Rate ◽  
Rate Of Convergence ◽  
Finite Order ◽  
Analytic Functions ◽  
Measure Zero ◽  
Logarithmic Derivative ◽  
Convergence Domain ◽  
Globally Convergent ◽  
Voronoi Polygons ◽  
Zeros Of Analytic Functions

Показано, что теорема Кенига о нулях аналитической функции, примененная к логарифмической производной целой функции конечного порядка, приводит к алгоритму отыскания нулей, для которого областями сходимости являются многоугольники Вороного искомых нулей. Так как диаграмма Вороного последовательности нулей составляет множество меры нуль, то алгоритм имеет глобальную сходимость. Дана оценка скорости сходимости. Для итераций высших порядков, которые строятся с помощью теоремы Кенига, рассмотрено влияние кратности корня на область сходимости и приводится оценка скорости сходимости. It is shown that Koenig's theorem on zeros of analytic functions applied to the logarithmic derivative of an integer function of finite order leads to an algorithm of finding zeros whose convergence domains are the Voronoi polygons of the zeros to be found. Since the Voronoi diagram of a sequence of zeros is a set of measure zero, this algorithm is globally convergent. The rate of convergence is estimated. For higher-order iterations that are constructed using Koenig's theorem, the effect of root multiplicity on the convergence domain is considered and the convergence rate is estimated for this case.

scholarly journals Globally convergent method for designing twice spline contractual function

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Zhichuan Zhu ◽  
Yonghong Yao ◽  
Mihai Postolache
Keyword(s):  
Initial Point ◽  
Principal Agent ◽  
Quadratic Spline ◽  
Feasible Set ◽  
Homotopy Algorithm ◽  
Kkt Systems ◽  
Globally Convergent ◽  
Principal Agent Problem ◽  
Convergent Method ◽  
Convergent Solution

Abstract To design a quadratic spline contractual function in the case of discretely unknown nodes, a modified constraint shifting homotopy algorithm for solving principal–agent problems is constructed in the paper. Then the existence of globally convergent solution to KKT systems for the principal–agent problem with spline contractual function is proved under a much weaker condition. The proposed algorithm only requires that any initial point is in the shifted feasible set but not necessarily in the original feasible set.

Convexity of a discrete Carleman weighted objective functional in an inverse medium scattering problem

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nguyen Trung Thành
Keyword(s):  
Finite Number ◽  
Scattering Problem ◽  
One Dimensional ◽  
Globally Convergent ◽  
Convergent Method ◽  
Inverse Medium ◽  
Inverse Medium Scattering ◽  
Objective Functional

AbstractWe investigate a globally convergent method for solving a one-dimensional inverse medium scattering problem using backscattering data at a finite number of frequencies. The proposed method is based on the minimization of a discrete Carleman weighted objective functional. The global convexity of this objective functional is proved.

scholarly journals A derivative free globally convergent method and its deformations

2021 ◽  
Author(s):  
Manoj Kumar Singh ◽  
Arvind K. Singh
Keyword(s):  
Difference Operator ◽  
Linear Equations ◽  
Numerical Test ◽  
Test Functions ◽  
Globally Convergent ◽  
Forward Difference ◽  
Derivative Free ◽  
Fractal Patterns ◽  
Convergent Method ◽  
Non Linear Equations

AbstractThe motive of the present work is to introduce and investigate the quadratically convergent Newton’s like method for solving the non-linear equations. We have studied some new properties of a Newton’s like method with examples and obtained a derivative-free globally convergent Newton’s like method using forward difference operator and bisection method. Finally, we have used various numerical test functions along with their fractal patterns to show the utility of the proposed method. These patterns support the numerical results and explain the compactness regarding the convergence, divergence and stability of the methods to different roots.

scholarly journals Logarithmic derivative estimates of meromorphic functions of finite order in the half-plane

2020 ◽  
Vol 54 (2) ◽  
pp. 172-187
Author(s):  
I.E. Chyzhykov ◽  
A.Z. Mokhon'ko
Keyword(s):  
Meromorphic Function ◽  
Finite Order ◽  
Half Plane ◽  
Meromorphic Functions ◽  
Logarithmic Derivative ◽  
Sharp Estimates ◽  
Exceptional Sets ◽  
Upper Half Plane ◽  
Logarithmic Derivatives

We established new sharp estimates outside exceptional sets for of the logarithmic derivatives $\frac{d^ {k} \log f(z)}{dz^k}$ and its generalization $\frac{f^{(k)}(z)}{f^{(j)}(z)}$, where $f$ is a meromorphic function $f$ in the upper half-plane, $k>j\ge0$ are integers. These estimates improve known estimates due to the second author in the class of meromorphic functions of finite order.Examples show that size of exceptional sets are best possible in some sense.

On perturbation range in the feedback synthesis problem for a chain of integrators system

2020 ◽  
Author(s):  
V I Korobov ◽  
T V Revina
Keyword(s):  
Finite Time ◽  
Initial Point ◽  
Settling Time ◽  
Time Function ◽  
Synthesis Problem ◽  
Total Derivative ◽  
Perturbed System ◽  
Arbitrary Initial Point ◽  
Feedback Synthesis ◽  
A Chain

Abstract The feedback synthesis problem for a chain of integrators system with continuous bounded unknown perturbation is considered. Our approach is based on the controllability function (CF) method proposed by V.I. Korobov. The perturbation range is determined by the negativity condition for the total derivative of the CF with respect to the perturbed system. The control that does not depend on perturbation under some restrictions and steers an arbitrary initial point from a neighborhood of the origin to the origin in a finite time (settling-time function) is constructed. The settling-time function depends on the perturbation, but it remains bounded from below and from above by the same value.

scholarly journals Hybrid Method with Perturbation for Lipschitzian Pseudocontractions

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Lu-Chuan Ceng ◽  
Ching-Feng Wen
Keyword(s):  
Nonlinear Operator ◽  
Real Hilbert Space ◽  
Initial Point ◽  
Nonempty Closed Convex Subset ◽  
Descent Method ◽  
Steepest Descent Method ◽  
Hybrid Steepest Descent Method ◽  
Arbitrary Initial Point ◽  
Mann’S Iteration ◽  
Fixed Point Sets

Assume thatFis a nonlinear operator which is Lipschitzian and strongly monotone on a nonempty closed convex subsetCof a real Hilbert spaceH. Assume also thatΩis the intersection of the fixed point sets of a finite number of Lipschitzian pseudocontractive self-mappings onC. By combining hybrid steepest-descent method, Mann’s iteration method and projection method, we devise a hybrid iterative algorithm with perturbationF, which generates two sequences from an arbitrary initial pointx0∈H. These two sequences are shown to converge in norm to the same pointPΩx0under very mild assumptions.

Application of optimization tasks in cluster analysis

10.12737/7483 ◽  
2014 ◽  
Vol 8 (7) ◽  
pp. 0-0
Author(s):  
Олег Сдвижков ◽  
Oleg Sdvizhkov
Keyword(s):  
Cluster Analysis ◽  
Spanning Tree ◽  
Minimum Spanning Tree ◽  
Clustering Algorithms ◽  
Clustering Methods ◽  
Number Of Clusters ◽  
Homogeneous Groups ◽  
Finite Set ◽  
Minimum Number

Cluster analysis [3] is a relatively new branch of mathematics that studies the methods partitioning a set of objects, given a finite set of attributes into homogeneous groups (clusters). Cluster analysis is widely used in psychology, sociology, economics (market segmentation), and many other areas in which there is a problem of classification of objects according to their characteristics. Clustering methods implemented in a package STATISTICA [1] and SPSS [2], they return the partitioning into clusters, clustering and dispersion statistics dendrogram of hierarchical clustering algorithms. MS Excel Macros for main clustering methods and application examples are given in the monograph [5]. One of the central problems of cluster analysis is to define some criteria for the number of clusters, we denote this number by K, into which separated are a given set of objects. There are several dozen approaches [4] to determine the number K. In particular, according to [6], the number of clusters K - minimum number which satisfies where - the minimum value of total dispersion for partitioning into K clusters, N - number of objects. Among the clusters automatically causes the consistent application of abnormal clusters [4]. In 2010, proposed and experimentally validated was a method for obtaining the number of K by applying the density function [4]. The article offers two simple approaches to determining K, where each cluster has at least two objects. In the first number K is determined by the shortest Hamiltonian cycles in the second - through the minimum spanning tree. The examples of clustering with detailed step by step solutions and graphic illustrations are suggested. Shown is the use of macro VBA Excel, which returns the minimum spanning tree to the problems of clustering. The article contains a macro code, with commentaries to the main unit.

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