The Lorenz system is defined by the third order set of ordinary differential equations:
dx/dt = sigma( y - x ),
dy/dt = rx - y - xz,
dz/dt = -bz + xy
If the parameter set is sigma=10, r=28, b=8/3, then the system response is chaotic. The Lorenz is one the hallmark examples used in illustrating nonlinear deterministic chaotic motion.