[ODE] Good reference for solving LCP's?

[Andrew Riehm]

I'm trying to understand how the physics engine works, from a numerical 
computing perspective, and I am having a hard time finding a good 
comprehensive overview of what a linear complimentarity problem is and 
what methods are used to solve them.  Can anyone point me to a good 
reference (be it an online article, a book, or a journal)?

--
Andrew Riehm