  Motivated by a class of orbit problems in astrophysics, this paper considers
solutions to Hill's equation with forcing strength parameters that vary from
cycle to cycle. The results are generalized to include period variations from
cycle to cycle. The development of the solutions to the differential equation
is governed by a discrete map. For the general case of Hill's equation in the
unstable limit, we consider separately the case of purely positive matrix
elements and those with mixed signs; we then find exact expressions, bounds,
and working estimates for the growth rates. We also find exact expressions,
estimates, and bounds for the infinite products of several $2 \times 2$
matrices with random variables in the matrix elements. In the limit of sharply
spiked forcing terms (the delta function limit), we find analytic solutions for
each cycle and for the discrete map that matches solutions from cycle to cycle;
for this case we find the growth rates and the condition for instability in the
limit of large forcing strength, as well as the widths of the stable/unstable
zones.
