Modelica

Modelica language is an object-oriented language for physics-based modeling — or physical modeling — for virtual prototyping of engineering.

It enables a very easy definition of a system model by graphically describing its topology. An electric circuit looks like an electric circuit on a computer screen: this circuit can then be easily connected to a mechanical system model through motor models, shafts, gears, and so on.

Learn more about it @ modelica.org

The language specifications may be found @ http://www.modelica.org/documents/ModelicaSpec22.pdf