Showing posts with label MCP. Show all posts
Showing posts with label MCP. Show all posts

Sunday, May 23, 2021

Solving linear complementarity problems without an LCP solver

Introduction


The linear complementarity problem (LCP) can be stated as [1]: 


LCP Problem
\[\begin{align} &\text{Find $\color{darkred}x\ge 0,\color{darkred}w\ge 0$ such that:}\\ & \color{darkred}x^T\color{darkred}w = 0 \\ &\color{darkred}w =\color{darkblue}M  \color{darkred}x + \color{darkblue}q\end{align}\]


In many cases we require that \(\color{darkblue}M\) is positive definite.

The LCP has different applications, including in finance, physics, and economics [2]. Off-the-shelf LCP solvers are not widely available. Here I will show how to solve LCPs with other solvers. This question comes up now and then, so here is a short recipe post.