  The framework of anisotropic hydrodynamics is generalized to include finite
particle masses. Two schemes are introduced and their predictions compared with
exact solutions of the kinetic equation in the relaxation time approximation.
The first formulation uses the zeroth and first moments of the kinetic
equation, whereas the second formulation uses the first and second moments. For
the case of one-dimensional boost-invariant expansion, our numerical results
indicate that the second formulation yields much better agreement with the
exact solutions.
