An introduction to the physical modeling language Modelica.

A new language called Modelica TM for physical modeling is developed in an international effort. The main objective is to make it easy to exchange models and model libraries. The design approach builds on noncausal modeling with true ordinary differential and algebraic equations and the use of object-oriented constructs to facilitate reuse of modeling knowledge. There are already several modeling language based on these ideas available from universities and small companies. There is also significant experience of using them in various applications. The aim of the Modelica effort is to unify the concepts and to design a new uniform language for model representation. The paper describes the effort and gives an overview of Modelica.