  For a universe with massive neutrinos, cold dark matter, and baryons, we
solve the linear perturbation equations analytically in the small-scale limit
and find agreement with numerical codes at the 1-2% level. The inclusion of
baryons, a cosmological constant, or spatial curvature reduces the small-scale
power and tightens limits on the neutrino density from observations of high
redshift objects. Using the asymptotic solution, we investigate neutrino infall
into potential wells and show that it can be described on all scales by a
growth function that depends on time, wavenumber, and cosmological parameters.
The growth function may be used to scale the present-day transfer functions
back in redshift. This allows us to construct the time-dependent transfer
function for each species from a single master function that is independent of
time, cosmological constant, and curvature.
