We discuss the diffusion of magnetic flux in a field-cooled (''hard'')
superconducting slab in a creep regime in which E proportional to \J\
(sigma)J. Bryksin and Dorogovtsev recently discussed flux diffusion in
a pinningless (''soft'') superconductor in which E proportional to \B
\J. This problem is closely related to the flux-creep one with sigma=1
, and provides additional insight into the possible types of behaviour
. We list a series of possible long-term asymptotic solutions of a sca
ling form, which are either analytically exact or accurately calculate
d. We check numerically that the relevant long-term solution is approa
ched after various initial conditions. Amongst other conclusions we fi
nd S=d(1n\M\)/d(1n t)-->-1/sigma or -1/2 sigma, after application and
removal of an additional field, according to whether the disturbance h
as reached the sample centre or not. A relaxing sandpile model appears
to have wide validity when creep is only a small correction to the cr
itical state, as when sigma-->infinity.