Indonesian Journal of Electrical Engineering and Computer Science Vol. 24, No. 3, December 2021, pp. 1399~1404 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v24.i3.pp1399-1404  1399 Journal homepage: http://ijeecs.iaescore.com Centroidal-polygon: a new modified Euler to improve speed of resistor-inductor circuit equation Nur Shahirah Zulkifli 1 , Nooraida Samsudin 2 , Suzanna Ridzuan Aw 3 , Wan Farah Hanan Wan Osman 4 , Shahreen Kasim 5 , Tole Sutikno 6 1,2,3,4 Department of Information Technology, TATI University College, Chukai, Malaysia 5 Faculty of Computing Science and Information Technology, Universiti Tun Hussein Onn, Parit Raja, Malaysia 6 Department of Electrical Engineering, Faculty of Industrial Technology, Universitas Ahmad Dahlan, Yogyakarta, Indonesia Article Info ABSTRACT Article history: Received Jul 17, 2021 Revised Oct 6, 2021 Accepted Oct 23, 2021 Two types of first-order circuits are resistor-capacitor (RC) and resistor- inductor (RL). This paper focuses on the RL circuit equation. The centroidal- polygon (CP) scheme will be tested using SCILAB 6.0 software. This new scheme (CP scheme) is addressed to improve the speed. For the first order circuit equation, the complexity is focused on the time complexity, which is speed of the time taken to complete the simulation in the electrical part. The CP scheme is compared with the previous studies, polygon (P) and harmonic-polygon (HP). The result shows that the CP scheme is less computational and an alternative to solve the first order circuit equation, and get the result quickly compared with the previous research. Keywords: Centroidal mean Euler method First-order circuit Harmonic-polygon Resistor-inductor This is an open access article under the CC BY-SA license. Corresponding Author: Nur Shahirah Zulkifli Department of Information Technology, TATI University College Kemaman, 24000 Chukai, Terengganu, Malaysia Email: shahirah.zulkifli.md@gmail.com 1. INTRODUCTION Euler method produces simple numerical solutions and enforces low computational cost to solve the ordinary differential equation (ODE) for a given initial value problem (IVP) [1]–[9]. Although the Euler method gives a simple solution, this method lacks accuracy [5], [9]. The Euler method will contribute to an error at every step size implied in the solution [8]. This is because the contribution of error is proportional to the phase size implied in the solution. Regarding this problem, it makes researchers enhance the Euler method known as the new modified Euler method [2], [8], [10]–[16]. Usually, the improved Euler approach is explicitly applied to mathematical fields only. This new modified Euler named centroidal polygon (CP) [17] has been tested into the linear and non-linear equation. The results proved that the mathematical problem could be solved using CP. Thus, this approach will be tested in the engineering field [18]. In mechanical engineering, the Euler method has also been known for studying the behavior of flow [19], [6], such as fluid dynamic computations. In this research, the CP concept is applied to electrical engineering. Ordinarily, in the electrical field, the calculation of speed will be conducted manually by reading the output from the oscillator using an analytical solution [20]. Thus, this research aims to examine the speed of the circuit equation using the modified Euler method. The arithmetic mean is one of the means used to improve the Euler. Arithmetic mean is the simplest form of mean,