Note on roots location of a symmetric polynomial with respect to the imaginary axis

2012 ◽  
Vol 60 (4) ◽  
pp. 499-510
Author(s):  
Hui-Feng Hao ◽  
Yong-Jian Hu ◽  
Gong-Ning Chen
Author(s):  
Deepali Khurana ◽  
Sushma Gupta ◽  
Sukhjit Singh

In the present article, we consider a class of univalent harmonic mappings, $\mathcal{C}_{T} = \left\{ T_{c}[f] =\frac{f+czf'}{1+c}+\overline{\frac{f-czf'}{1+c}}; \; c>0\;\right\}$ and $f$ is convex univalent in $\mathbb{D}$, whose functions map the open unit disk $\mathbb{D}$ onto a domain convex in the direction of the imaginary axis. We estimate coefficient, growth and distortion bounds for the functions of the same class.


1996 ◽  
Vol 29 (1) ◽  
pp. 1263-1268
Author(s):  
Chyi Hwang ◽  
Bo-Win Lin ◽  
Tong-Yi Guo

2007 ◽  
Vol 79 (4) ◽  
pp. 563-575 ◽  
Author(s):  
Jaume Llibre ◽  
Marcelo Messias

In this paper we study a class of symmetric polynomial differential systems in R³, which has a set of parallel invariant straight lines, forming degenerate heteroclinic cycles, which have their two singular endpoints at infinity. The global study near infinity is performed using the Poincaré compactification. We prove that for all n <FONT FACE=Symbol>Î</FONT> N there is epsilonn > 0 such that for 0 < epsilon < epsilonn the system has at least n large amplitude periodic orbits bifurcating from the heteroclinic loop formed by the two invariant straight lines closest to the x-axis, one contained in the half-space y > 0 and the other in y < 0.


2018 ◽  
Vol 18 (4) ◽  
pp. 673-685 ◽  
Author(s):  
Vitalii G. Kurbatov ◽  
Irina V. Kurbatova

AbstractIt is well known that the equation {x^{\prime}(t)=Ax(t)+f(t)}, where A is a square matrix, has a unique bounded solution x for any bounded continuous free term f, provided the coefficient A has no eigenvalues on the imaginary axis. This solution can be represented in the formx(t)=\int_{-\infty}^{\infty}\mathcal{G}(t-s)f(s)\,ds.The kernel {\mathcal{G}} is called Green’s function. In this paper, for approximate calculation of {\mathcal{G}}, the Newton interpolating polynomial of a special function {g_{t}} is used. An estimate of the sensitivity of the problem is given. The results of numerical experiments are presented.


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