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Johan Matheus Tuwankotta
Analysis and Geometry Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung
Mathematics

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TWO ASPECTS OF A GENERALIZED FIBONACCI SEQUENCE Tuwankotta, Johan Matheus
Journal of the Indonesian Mathematical Society Volume 21 Number 1 (April 2015)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.21.1.173.1-17

Abstract

In this paper we study the so-called generalized Fibonacci sequence: $x_{n+2} = \alpha x_{n+1} + \beta x_n, n\in \mathbb{N}$.  We derive an open domain around the origin of the parameter space where the sequence converges to $0$.  The limiting behavior on the boundary of this domain are: convergence to a nontrivial limit, $k$-periodic ($k\in \mathbb{N}$), or quasi-periodic.  We use the ratio of two consecutive terms of the sequence to construct a rational approximation for algebraic numbers of the form: $\sqrt{r}, r\in \mathbb{Q}$.  Using a similar idea, we extend this to higher dimension to construct a rational approximation for  $\sqrt[3]{ a + b\sqrt{c}} +  \sqrt[3]{ a - b\sqrt{c}} + d$.DOI : http://dx.doi.org/10.22342/jims.21.1.173.1-17
Application of Lagrange Multiplier Method for Computing Fold Bifurcation Point in A Two-Prey One Predator Dynamical System Marwan, Marwan; Tuwankotta, Johan Matheus; Harjanto, Eric
Journal of the Indonesian Mathematical Society Volume 24 Number 2 (October 2018)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.24.2.595.7-19

Abstract

We propose by means of an example of applications of the classical Lagrange Multiplier Method for computing fold bifurcation point of an equilibrium ina one-parameter family of dynamical systems. We have used the fact that an equilibrium of a system, geometrically can be seen as an intersection between nullcline manifolds of the system. Thus, we can view the problem of two collapsing equilibria as a constrained optimization problem, where one of the nullclines acts as the cost function while the other nullclines act as the constraints.
Co-Authors Harjanto, Eric Marwan Marwan