num4lcp: Numerical methods (NUM) for (4) linear complementarity problems (LCP) in physics-based animation. This library contains a toolbox of Matlab functions that implements numerical methods for computing solutions for linear complementarity problems (LCPs). The intend with this library is that users can learn and study the algorithms behind the numerical methods before selecting their favorite method and porting it to whatever target language or platform they wish for. The hope is that this will allow other researchers and practitioners to easily adopt new numerical methods into their own projects.