Combination of Excel Functions and VBA as Tools to Solve Linear Equation System (LES) Models (Simulation of Mathematical Model for Daily Nutritional Intake Portions for School-Aged Children Aged 7 to 9 Years Old)

Abstract

The solution of Linear Equation Systems (LES) is essential in solving problems in various fields such as agriculture, healthcare, industry, economics, and engineering, providing a foundation for modeling and solving complex issues. The integration of Microsoft Excel's built-in functions and Visual Basic for Applications (VBA) offers an effective and efficient approach to solving these LES models. This study explores the theory behind converting LES to matrix equations, the advantages of using Excel functions and VBA, as well as the application of functions like MDeterm, MInverse, and MMult. In the research trials on LES models with daily intake portions (energy, protein, fat, carbohydrate) for school-aged children 7 to 9 years old with 4 variables (plant-based, animal-based, vegetables, fruits) and the algorithm in this study can be extended for n variables, also discussing the conditions for single solutions, multiple solutions, and no solutions. The discussion includes the creation of programming algorithms and VBA Excel code, as well as the visualization of the program's results.