  Results for the late-time regime of phase ordering in three dimensions are
reported, based on numerical integration of the time-dependent Ginzburg-Landau
equation with nonconserved order parameter at zero temperature. For very large
systems ($700^3$) at late times, $t \ge 150,$ the characteristic length grows
as a power law, $R(t) \sim t^n$, with the measured $n$ in agreement with the
theoretically expected result $n=1/2$ to within statistical errors. In this
time regime $R(t)$ is found to be in excellent agreement with the analytical
result of Ohta, Jasnow, and Kawasaki [Phys. Rev. Lett. {\bf 49}, 1223 (1982)].
At early times, good agreement is found between the simulations and the
linearized theory with corrections due to the lattice anisotropy.
