1. Change Rate Concepts and their Realization in the MM&S: A Computer Program for Modeling and Simulation of Dynamic Systems

The concept of “four element groups” means that all elements of a dynamic system can be divided into four groups: (1) constant elements, (2) state elements, (3) intermediate elements, (4) listed elements. This concept is realized in my MM&S-computer program with two facts. The first one is that four above mentioned element groups are correspondingly assigned four symbols: circle, square, rhombus, circle with three signs (these signs signal how we should handle this listed element at time point where its value has not been declared). These symbols are used to draw simulation scheme of interaction of the system elements. The concept of “change rate” means that every state element has a change rate as its attribute. Other elements of the system affect current state element by affecting its change rate. The current state element affects other elements of the system with its value. This concept is realized in my MM&S-computer program with the fact, that the links connect the state elements directly. In case if a state element has a incoming link, we understand that the change rate of this state element is being affected. Once change rate is an attribute of the state element, the value of the state element can be automatically used for the calculation of change rate. Realization of these above concepts make the simulation scheme of a dynamic system more clear and simple. This paper gives the reasoning for these concepts and also describes the model formats, model calculation in MM&S-computer program.