  Sharp two- and three-dimensional phase transitional magnetization curves are
obtained by an iterative renormalization-group coupling of Ising chains, which
are solved exactly. The chains by themselves do not have a phase transition or
non-zero magnetization, but the method reflects crossover from temperature-like
to field-like renormalization-group flows as the mechanism for the
higher-dimensional phase transitions. The magnetization of each chain acts, via
the interaction constant, as a magnetic field on its neighboring chains, thus
entering its renormalization-group calculation. The method is highly flexible
for wide application.
