Several tools exist to create and work with computational models. Proprietary tools like MATLAB66 as well as free tools like Scilab67 are used by hundreds of thousands of researchers, academics and engineers around the world to build complex computational models to design everything ranging from space crafts to smart power grids. Computational models can also be built using almost any programming languages although declarative programming paradigms such as those offered by languages like Modelica68 are typically best suited for this.