1. Mathematics Department, Faculty of Sciences and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim 35900, Malaysia
2. Faculty of Science and Technology, UIN Sultan Syarif Kasim, Pekanbaru 28293, Indonesia
3. Statistics Department, Giresun University, Giresun 28200, Turkey
4. Power Distribution Unit Pekanbaru, State Electricity Company Indonesia, P. Sekaki, Pekanbaru 28291, Indonesia
5. Electrical Engineering Department, Politeknik Caltex Riau, Rumbai 28265, Indonesia
6. Electrical Department, Universitas Riau, Pekanbaru 28291, Indonesia