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Faculty of Mathematics and Natural Sciences, Brawijaya University. Jl. Veteran, Malang City, East Java, Indonesia
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INDONESIA
Indonesian Journal of Mathematics and Applications
Published by Universitas Brawijaya
ISSN : -     EISSN : 29868149     DOI : https://doi.org/10.21776/ub.ijma
Core Subject : Science, Education,
Computer Science & IT Education Mathematics Other
The Indonesian Journal of Mathematics and Applications is a journal managed by Universitas Brawijaya, Malang, Indonesia, that is published twice a year (in March and September). IJMA is devoted to research articles of the highest quality in all areas of mathematics and its applications, statistics, and data science. The journal covers the following topics: Mathematical Analysis, Algebra, Biomathematics, Industrial Mathematics, Operasion Research, and Optimization, Data Sciences/Soft computing, Mathematical Physics, Financial Mathematics and Actuarial Sciences, Statictics. Upon its submission, the Editor-in-Chief decides on the suitability of the paper’s content for the aim and scope of the IJMA. If the Editor in Chief considers the paper is suitable, then the paper will be sent for peer reviewing by two peer reviewers. The Indonesian Journal of Mathematics and Applications maintains double anonymity, so neither the peer reviewers nor the author(s) can be identified by one another. The peer reviewers are respected scholars in the areas. The Indonesian Journal of Mathematics and Applications is an open access, peer-reviewed journal that considers articles describing novel computational algorithms and software, models and tools, including statistical methods, machine learning, and artificial intelligence, as well as systems biology.
Arjuna Subject : Matematika - Matematika Terapan
Articles 55 Documents
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Implementation of Holt-Winter Exponential Smoothing Method to Forecast The Spread of Covid-19 Pangestu, Adhitama Ihza; Andayani, Puji
Indonesian Journal of Mathematics and Applications Vol. 1 No. 2 (2023): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2023.001.02.2

Abstract

This research examines the Holt winters exponential smoothing method to solve forecasting problems using case studies of the spread of Covid-19. The data source uses the transmission of Covid-19 in Indonesia. MAPE is used to measure errors in data forecasting. The results are structured to serve as a recommendation for other researchers in choosing a method for predicting the spread of the disease. Based on the results, forecasting with the Holt-Winters model in positive cases produces a MAPE value of 9.21% using the Multiplicative model and the best parameter values of alpha, beta and gamma (0.4, 0.05, 0.25). Whereas in the case of human recovery, the MAPE value was 11.86% using the Multiplicative model and the best values for the parameters alpha, beta and gamma (0.4, 0.03, 0.1). And in the case of death it produces a MAPE of 17.97% using the Multiplicative model and the parameter values alpha, beta and gamma (0.4, 0.01, 0.1). So, it can be concluded that the Holt-Winters method on human positive case data shows a good outcome performance while recovered and deceased cases produce a well-being analysis performance.
Finite Difference Scheme for Nonlinear Finite Grating without and with Defect Purnomo, Reymond
Indonesian Journal of Mathematics and Applications Vol. 1 No. 1 (2023): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2023.001.01.5

Abstract

We present a simple numerical scheme based on finite difference method (FDM) with different boundary treatments to study the nonlinear optical response of finite one-dimensional grating with Kerr medium. For linear and nonlinear case, we use the second order numerical scheme for interior with different treatments of boundary conditions. The resulting of nonlinear system of equations is solved using Newton method with continuation method. To illustrate this method, we consider a periodic medium with and without defect. As the result, this method is able to show the bandgap and optical bistability phenomena for both mediums.
Numerical Solution of Burgers Equation using Cubic B-Spline Collocation Method and Neumann Boundary Condition Mulya Lezani, Nadine; Habibah, Ummu
Indonesian Journal of Mathematics and Applications Vol. 1 No. 2 (2023): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2023.001.02.3

Abstract

Burgers equation is one of the nonlinear differential equations which is generally difficult to determine its analytical solution, so it is necessary to do a numerical approach. This article discusses the numerical solution of the Burgers equation using the Cubic B-Spline Collocation method. The first step is to derive the numerical scheme using the Cubic B-Spline Collocation method for the space variable and the Crank-Nicholson method for the time variable. Furthermore, based on von Neumann stability analysis, it is obtained that the numerical scheme of Burgers equation is unconditionally stable. By performing numerical simulations using different  and    step sizes, it can be shown that the absolute value of the resulting error will be smaller for the step sizes of   and which is getting smaller.
Comparison of Random Forest, XGBoost, and LightGBM Methods in Estimating Airbnb Accommodation Rental Prices Based on Customers in New York City Tauryawati, meylista
Indonesian Journal of Mathematics and Applications Vol. 1 No. 2 (2023): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2023.001.02.5

Abstract

The research data was taken from a dataset provided by Inside Airbnb, and the analysis was conducted using machine learning techniques with Random Forest, XGBoost, and LightGBM algorithms. The research stages include data understanding, data preprocessing, data analysis, modeling, model evaluation, and rental price estimation. It is expected that the results of this study can help customers estimate the rental price of Airbnb rooms.
Neutral Caputo-Fabrizio Fractional Differential Equation with Hyers-Ulam Stability Rohman, Minanur; Eryilmaz, Ilker; Huda, M. N.
Indonesian Journal of Mathematics and Applications Vol. 1 No. 2 (2023): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2023.001.02.1

Abstract

In this paper, we will discuss the existence and uniqueness of a neutral Caputo-Fabrizio differential equation which fulfills several required conditions. Furthermore, using the Picard operator, we show that the problem has Hyers-Ulam type stability.
Multiplication of Matrices Keleş, Hasan
Indonesian Journal of Mathematics and Applications Vol. 2 No. 1 (2024): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2024.002.01.1

Abstract

This study is about multiplication of matrices. Multiplication of real numbers, which can be written along a line, is also two way. Here, the direction is not an influential factor even when the elements are switched. For example $3.2=6$ and $2.3=6. $ In matrices this makes left and right multiplication is mandatory. Left multiplication is already defined. This is multiplication in known matrices. Left multiplication is used in the studies since the definition of this operation until today. The most insurmountable situation here is that matrices do not commutative Property according to this operation. The left product is taken into account, when $AB $ is written. Here the matrix $A$ is made to be effective. This left product is denoted by $AB. $ The right definition in this study is denoted by $\underleftarrow{AB}. $ This operation multiplication is seen to be compatible with the left multiplication. The commutativity property in matrices is reinvestigated with this approach. The relation between the right multiplication and the Cracovian Product is given by J. Koci´nski (2004).
A Classical Survey On Rotundity of Norms in Banach Spaces Wanjara, Amos Otieno
Indonesian Journal of Mathematics and Applications Vol. 2 No. 1 (2024): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2024.002.01.5

Abstract

The study on rotundity of norms in Banach spaces is of interest to many mathematicians. This is because rotundity properties are strongly applicable in many branches of Mathematics including but not restricted to functional analysis and topology. Some of the properties include: Rotund, Locally Uniformly Rotund, Uniformly Rotund in every direction, Uniformly Rotund in Weakly Compact sets of direction among others. In this paper, we give a survey of the standard results that will really revolutionize the study and research on rotundity of norms in the fields of functional analysis and topology among others.
Conditional Beta Approximation: Two Applications Habibi, Reza
Indonesian Journal of Mathematics and Applications Vol. 2 No. 1 (2024): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2024.002.01.2

Abstract

Suppose that X,Y are two independent positive continuous random variables. Let P=X/(X+Y) and Z=X+Y. If X, Y have gamma distributions with the same scale parameter, then P distribution will be beta and P, Z are independent.  In the case that the distributions of these two variables are not gamma, the P distribution is well approximated by the beta distribution. However, P,Z are dependent. According to matching moment method, it is necessary to compute the moments of conditional distribution for beta fitting. In this paper, some new methods for computing moments of conditional distribution of P given Z are proposed. First of all, it is suggested to consider the regression method. Then Monte Carlo simulation is advised. The Bayesian posterior distribution of P is suggested. Applications of differential equations are also reviewed. These results are applied in two applications namely variance change point detection and winning percentage of gambling game are proposed. The probability of change in variance in a sequence of variables, as a leading indicator of possible change, is proposed. Similarly, the probability of winning in a sequential gambling framework is proposed. The optimal time to exit of gambling game is proposed. A game theoretic approach to problem of optimal exit time is proposed. In all cases, beta approximations are proposed. Finally, a conclusion section is also given.
A Convex Polygon of Twist Influenced by Nandakumar and Ramana Rao Rellon, Louie Resti S.; Gardose, Angelito D.; Cal, Kesler Jason P.; Licong, Nikko Syrus L.; Sarte, Karl Madison E.
Indonesian Journal of Mathematics and Applications Vol. 2 No. 1 (2024): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2024.002.01.4

Abstract

In this study, the researchers address the conundrum: To divide a 2-dimensional convex polygonal region Q into a specified natural number n of convex pieces, all of which have equal areas although perimeters could be different, such that the total length of cuts used is maximized. With the aid of AutoCAD software, the results show that a convex polygon Q divided into n=2 equal area partitions must have its cut line λ or its area bisector originate in some vertex "v" _"α" of Q with the least measure. We claim that this cut line λ is the maximum possible cut length that divides polygon Q into n=2 equal area partitions. The resulting proof of this conjecture can be used recursively for a convex polygon Q divided into n=2k equal area partitions, where k∈N
Optimization Algorithms for Enhanced Parameter Estimation in Mathematical Modelling Hasan, Ahmed; Mzedawee, Asaad Naser Hussein; Alsharify, Fouad Hamza Abd
Indonesian Journal of Mathematics and Applications Vol. 2 No. 1 (2024): Indonesian Journal of Mathematics and Applications
Publisher : Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.ijma.2024.002.01.3

Abstract

Identifying optimization algorithms for parameter estimation is an important consideration in the dynamic landscape of computational science and mathematical modeling. This paper explores the complex relationship between mathematical models and optimization techniques, providing a comprehensive analysis of synergies a lies between them for they were established in order search. Our study attempted to shed light on its role in theoretical and practical terms: three important factors: perception, meeting behavior, and mathematical efficiency. In doing so, we found valuable insights into the art of algorithm selection, which provided useful insights into improving the accuracy and efficiency of mathematical models. Based on the presented results, the Powell optimization algorithm emerged as an outstanding tool, and model and algorithm continued to demonstrate multiple applicability in various sampling scenarios. By revealing complex interconnections, this study contributes to a growing discourse about mathematical modeling and optimization, and equips scientists, engineers, and decision-makers with the tools needed to meet complex real-world challenges with confidence and accuracy. Finally, the numerical results of the optimization show the superiority of Powell's algorithm in reaching the optimal solution and demonstrated its ability to deal with a wide range of scenarios.

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