Dymola

Dymola is an object-oriented language and a program for modeling large systems. Reuse of modeling knowledge is supported by use of libraries containing model classes and through inheritance. The user need not convert the equations to assignment statements. This is done symbolically by Dymola. Matrix equations facilitate convenient modeling of 3-D mechanical systems, control systems, etc. Discontinuous equations and instantaneous equations are supported to model friction, impact and difference equations. Dymola automatically generates the needed time and state events. 

Typical Dymola users have complex models with tens of thousands of equations mostly from the multibody domain, and also need support for electrical circuits, drivetrains and control systems. Many universities use Dymola because of the unified approach to physical modeling. Dymola can translate a physical model to an S-function, MATLAB code, or MEX-file which can be used as a block in Simulink. Algebraic loops are automatically solved. Approximate state event handling suitable for real-time simulation is supported.