Journal of Research in Mathematics Trends and Technology <p class="western" lang="en-US" align="justify">Journal of Research in Mathematics Trends and Technology (JoRMTT) is an international journal, open access which provides advance forum and focused to study in every aspect of pure mathematics and its application. Besides, JoRMTT also publishes real time articles survey, recently trends, new theoretical techniques, new ideas, and mathematical tools in whole branches of mathematics. One of the purpose is to reflect research progress in Indonesia and by providing international forum, to stimulate future progress.</p> <p class="western" lang="en-US" align="justify">Every paper will be published by TALENTA Publisher under management of Department of Mathematics, Faculty of Mathematics and Science, University of Sumatera Utara. The frequency of the publishing are twice in a year which are on March and September with maximum papers to be published are 5 papers.</p> Talenta Publisher en-US Journal of Research in Mathematics Trends and Technology 2656-1514 <p><a name="coptf"></a>Authors submitting a manuscript do so on the understanding that if accepted for publication, copyright of the article shall be assigned to Journal of Research in Mathematics Trends and Technology (JoRMTT) and Faculty of Mathematics and Natural Sciences as well as TALENTA Publisher Universitas Sumatera Utara as publisher of the journal.</p> <p>Authors understand that they will maintain/hold/keep the copyright of the articles submitted to JoRMTT. Consecutively, authors still retain the rights to use and share the published articles without written permission from JoRMTT, as long as they follow the <a href="" target="_blank" rel="noopener">Creative Commons Licensing Terms</a>&nbsp;as set forth by Creative Commons. 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You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use)</li> <li class="show">NonCommercial (may not use the material for commercial purposes)</li> <li class="show">ShareAlike (If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original)</li> <li class="show">No additional restrictions (You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits)</li> </ol> <p><strong>Notices:</strong><br>You do not have to comply with the license for elements of the material in the public domain or where your use is permitted by an applicable exception or limitation.<br>No warranties are given. The license may not give you all of the permissions necessary for your intended use. For example, other rights such as publicity, privacy, or moral rights may limit how you use the material.</p> Monte Carlo Simulation Approach to Determine the Optimal Solution of Probabilistic Supply Cost <p><span class="fontstyle0">Monte Carlo simulation is a probabilistic simulation where the solution of problem is given based on random process. The random process involves a probability<br>distribution from data variable collected based on historical data. The used model is probabilistic Economic Order Quantity Model (EOQ). This model then assumed use Monte Carlo simulation, so that obtained the total of optimal supply cost in the future. Based on data processing, the result of probabilistic EOQ is $486128,19. After simulation using Monte Carlo simulation where the demand data follows normal distribution and it is obtained the total of supply cost is $46116,05 in 23 months later. Whereas the demand data uses Weibull distribution is obtained the total of supply stock is $482301,76. So that, Monte Carlo simulation can calculate the total of optimal supply in the future based on historical demand data.</span></p> Helmi Ramadan Prana Ugiana Gio Elly Rosmaini Copyright (c) 2020 Journal of Research in Mathematics Trends and Technology 2020-02-24 2020-02-24 2 1 1 6 10.32734/jormtt.v2i1.3752 Existence of Polynomial Combinatorics Graph Solution <p><span class="fontstyle0">The Polynomial Combinatorics comes from optimization problem combinatorial in form the nonlinear and integer programming. This paper present a condition such that the polynomial combinatorics has solution. Existence of optimum value will be found by restriction of decision variable and properties of feasible solution set or polyhedra.</span></p> Mardiningsih Saib Suwilo Ihda Hasbiyati Copyright (c) 2020 Journal of Research in Mathematics Trends and Technology 2020-02-24 2020-02-24 2 1 7 13 10.32734/jormtt.v2i1.3755 Estimation of Heteroskedasticity Semiparametric Regression Curve Using Fourier Series Approach <p>A heteroskedastic semiparametric regression model consists of two main <br>components, i.e. parametric component and nonparametric component. The model assumes <br>that any data (x̰ i′ , t i , y i ) follows y i = x̰ i′ β̰+ f(t i ) + σ i ε i , where i = 1,2, … , n , x̰ i′ = (1, x i1 , x i2 , … , x ir ) and t i <br>is the predictor variable. Parameter vector β̰ = (β 1 , β 2 , … , β r ) ′ ∈ ℜ r is unknown and f(t i ) is also unknown and is assumed to be in interval of C[0,π] . <br>Random error ε i is independent on zero mean and variance<br>σ 2 . Estimation of the <br>heteroskedastic semiparametric regression model was conducted to evaluate the parametric <br>and nonparametric components. The nonparametric component f(t i ) regression was <br>approximated by Fourier series F(t) = bt + 1<br>2 α 0 + ∑ α k 𝑐 𝑜𝑠 kt Kk=1 . The estimation was <br>obtained by means of Weighted Penalized Least Square (WPLS): min f∈C(0,π) {n −1 (y̰− Xβ̰−<br>f̰) ′ W −1 (y̰− Xβ̰− f̰) + λ ∫ 2<br>π [f ′′ (t)] 2 dt π<br>0 } . The WPLS solution provided nonparametric <br>component f̰̂ λ (t) = M(λ)y̰ ∗ for a matrix M(λ) and parametric component β̰̂ = [X ′ T(λ)X] −1 X ′ T(λ)y̰</p> Rahmawati Pane Sutarman Copyright (c) 2020 Journal of Research in Mathematics Trends and Technology 2020-02-24 2020-02-24 2 1 14 20 10.32734/jormtt.v2i1.3744 Comparison of Rainfall Forecasting in Simple Moving Average (SMA) and Weighted Moving Average (WMA) Methods (Case Study at Village of Gampong Blang Bintang, Big Aceh District-Sumatera-Indonesia <p><span class="fontstyle0">The changing climate causes rainfall to vary from period to period. This change has an impact on society, especially in agriculture such as crop failure. This study aims to predict rainfall in 2018 and 2019 with the Simple Moving Average (SMA) method and the Weighted Moving Average (WMA) method. Based on 2004-2018 data, the dry season occurs in February-October and the rainy season in November-January. The level of validation of forecasters in 2018 according to each the SMA method and the WMA method were 43.43% and 40.69%, respectively. Both of these methods are low and reasonable or acceptable. Based on the SMA method, the division of the dry season in 2019 is estimated in February-October while the distribution of the rainy season in the same year is in December-January. Based on the WMA Method that the distribution of the dry season is estimated in February-April, June-September and the rainy season in October-January and May.</span></p> Siti Rusdiana Syarifah Meurah Yuni Delia Khairunnisa Copyright (c) 2020 Journal of Research in Mathematics Trends and Technology 2020-02-24 2020-02-24 2 1 21 27 10.32734/jormtt.v2i1.3753 Loglinear Model Formation using Hierachial Backward Method <p><span class="fontstyle0">The loglinear model is a special case of a general linear model for poisson<br>distributed data. The loglinear model is also a number of models in statistics that are used to<br>determine dependencies between several variables on a categorical scale. The number of<br>variables discussed in this study were three variables. After the variables are investigated,<br>the formation of the loglinear model becomes important because not all the model<br>interaction factors that exist in the complete model become significant in the resulting<br>model. The formation of the loglinear model in this study uses the Backward Hierarchical<br>method. This research makes loglinear modeling to get the model using the Hierarchical<br>Backward method to choose a good method in making models with existing examples.<br>From the challenging examples that have been done, it is known that the Hierarchical<br>Reverse method can model the third iteration or scroll. Then, also use better assessment<br>methods about faster workmanship and computer-sponsored assessments that are used more<br>efficiently through compatibility testing for each model made</span></p> Siti Fatimah Sihotang Zuhri Copyright (c) 2020 Journal of Research in Mathematics Trends and Technology 2020-02-24 2020-02-24 2 1 28 36 10.32734/jormtt.v2i1.3754