  We consider the zero-temperature random-field Ising model in the presence of
an external field, on ladders and in one dimension with finite range
interactions, for unbounded continuous distributions of random fields, and show
that there is no jump discontinuity in the magnetizations for any quasi-one
dimensional model. We show that the evolution of the system at an external
field can be described by a stochastic matrix and the magnetization can be
obtained using the eigenvector of the matrix corresponding to the eigenvalue
one, which is continuous and differentiable function of the external field.
