Convergence analysis for a new faster four steps iterative algorithm with an application
OMA-Vol. 5 (2021), Issue 2, pp. 95 – 112 Open Access Full-Text PDF
Unwana Effiong Udofia, Austine Efut Ofem, Donatus Ikechi Igbokwe
Abstract:In this paper, we introduce a four step iterative algorithm which converges faster than some leading iterative algorithms in the literature. We show that our new iterative scheme is \(T\)-stable and data dependent. As an application, we use the new iterative algorithm to find the unique solution of a nonlinear integral equation. Our results are generalizations and improvements of several well known results in the existing literature.
Simpson’s type inequalities for exponentially convex functions with applications
OMA-Vol. 5 (2021), Issue 2, pp. 84 – 94 Open Access Full-Text PDF
Yenny Rangel-Oliveros, Eze R. Nwaeze
Abstract:The Simpson’s inequality cannot be applied to a function that is twice differentiable but not four times differentiable or have a bounded fourth derivative in the interval under consideration. Loads of articles are bound for twice differentiable convex functions but nothing, to the best of our knowledge, is known yet for twice differentiable exponentially convex and quasi-convex functions. In this paper, we aim to do justice to this query. For this, we prove several Simpson’s type inequalities for exponentially convex and exponentially quasi-convex functions. Our findings refine, generalize and complement existing results in the literature. We regain previously known results by taking \(\alpha=0\). In addition, we also show the importance of our results by applying them to some special means of positive real numbers and to the Simpson’s quadrature rule. The obtained results can be extended for different kinds of convex functions.
Limit cycles of a planar differential system via averaging theory
OMA-Vol. 5 (2021), Issue 2, pp. 73 – 83 Open Access Full-Text PDF
Houdeifa Melki, Amar Makhlouf
Abstract:In this article, we consider the limit cycles of a class of planar polynomial differential systems of the form
$$\dot{x}=-y+\varepsilon (1+\sin ^{n}\theta )xP(x,y)$$
$$ \dot{y}=x+\varepsilon (1+\cos ^{m}\theta )yQ(x,y),
$$
where \(P(x,y)\) and \(Q(x,y)\) are polynomials of degree \(n_{1}\) and \(n_{2}\) respectively and \(\varepsilon\) is a small parameter. We obtain the maximum number of limit cycles that bifurcate from the periodic orbits of a linear center \(\dot{x}=-y, \dot{y}=x,\) by using the averaging theory of first order.
$$\dot{x}=-y+\varepsilon (1+\sin ^{n}\theta )xP(x,y)$$
$$ \dot{y}=x+\varepsilon (1+\cos ^{m}\theta )yQ(x,y),
$$
where \(P(x,y)\) and \(Q(x,y)\) are polynomials of degree \(n_{1}\) and \(n_{2}\) respectively and \(\varepsilon\) is a small parameter. We obtain the maximum number of limit cycles that bifurcate from the periodic orbits of a linear center \(\dot{x}=-y, \dot{y}=x,\) by using the averaging theory of first order.
Asymptotic approximation of central binomial coefficients with rigorous error bounds
OMS-Vol. 5 (2021), Issue 1, pp. 380 – 386 Open Access Full-Text PDF
Richard P. Brent
Abstract:We show that a well-known asymptotic series for the logarithm of the central binomial coefficient is strictly enveloping in the sense of Pólya and Szegö, so the error incurred in truncating the series is of the same sign as the next term, and is bounded in magnitude by that term. We consider closely related asymptotic series for Binet’s function, for \(\ln\Gamma(z+\frac12)\), and for the Riemann-Siegel theta function, and make some historical remarks.
Tail distribution estimates of the mixed-fractional CEV model
OMS-Vol. 5 (2021), Issue 1, pp. 371 – 379 Open Access Full-Text PDF
Nguyen Thu Hang, Pham Thi Phuong Thuy
Abstract:The aim of this paper is to study the tail distribution of the CEV model driven by Brownian motion and fractional Brownian motion. Based on the techniques of Malliavin calculus and a result established recently in [1], we obtain an explicit estimate for tail distributions.
Reachability results in labelled \(t\)-ary trees
OMS-Vol. 5 (2021), Issue 1, pp. 360 – 370 Open Access Full-Text PDF
Isaac Owino Okoth, Albert Oloo Nyariaro
Abstract:In this paper, we prove some new formulas in the enumeration of labelled \(t\)-ary trees by path lengths. We treat trees having their edges oriented from a vertex of lower label towards a vertex of higher label. Among other results, we obtain counting formulas for the number of \(t\)-ary trees on \(n\) vertices in which there are paths of length \(\ell\) starting at a root with label \(i\) and ending at a vertex, sink, leaf sink, first child, non-first child and non-leaf. For each statistic, the average number of these reachable vertices is obtained for any random \(t\)-ary tree.
