  The continued-fraction method was developed systematically by Risken and
co-workers to solve problems of arbitrary fluctuations in nonlinear systems.
However, this efficient technique is limited to problems with a few variables,
which in practice means systems of noninteracting entities (particles, spins,
etc.) We illustrate how to extend the continued-fraction method to weakly
coupled systems with the problem of relaxation in classical spins.

Statistical Mechanics