  We analyze the scaling behavior of the two smallest Lyapunov exponents for
electrons propagating on two-dimensional lattices with energies within a very
narrow interval around the chiral critical point at E=0 in the presence of a
perpendicular random magnetic flux. By a numerical analysis of the energy and
size dependence we confirm that the two smallest Lyapunov exponents are
functions of a single parameter. The latter is given by ln L/ln xi(E), which is
the ratio of the logarithm of the system width L to the logarithm of the
correlation length xi(E). Close to the chiral critical point and energy |E| <<
E_0, we find a logarithmically divergent energy dependence lnxi(E)proporitonal
to |\ln(E_0/|E|)|^{1/2}, where E_0 is a characteristic energy scale. Our data
are in agreement with the theoretical prediction of M. Fabrizio and C.
Castelliani [Nucl.\Phys.B 583, 542 (2000)] and resolve an inconsistency of
previous numerical work.
