  A new method is developed to extend the histogram method to lattices with any
type of disorder. The Monte Carlo single- and multiple-histogram methods were
developed to get the most out of only a few simulations, but are restricted to
simulations with identical lattice configurations. The method introduced here
expands on the histogram method to allow data from various disordered lattice
configurations to be optimally combined in a single weighted average result.
This method is applied to a simple Ising-like model of the relaxor
ferroelectric perovskite solid solution $BaTiO_3$ - $Bi(Zn_{1/2}Ti_{1/2})O_3$
(BT-BZT), in which disorder plays a pivotal role.
