  We study two schemes for a time-fractional Fokker-Planck equation with space-
and time-dependent forcing in one space dimension. The first scheme is
continuous in time and is discretized in space using a piecewise-linear
Galerkin finite element method. The second is continuous in space and employs a
time-stepping procedure similar to the classical implicit Euler method. We show
that the space discretization is second-order accurate in the spatial
$L_2$-norm, uniformly in time, whereas the corresponding error for the
time-stepping scheme is $O(k^\alpha)$ for a uniform time step $k$, where
$\alpha\in(1/2,1)$ is the fractional diffusion parameter. In numerical
experiments using a combined, fully-discrete method, we observe convergence
behaviour consistent with these results.
