  In this work we investigate the classical ferromagnetic XY-model in two
dimensions subject to a symmetry breaking field which impose a $Z_2$ symmetry
to the system. We used the broad histogram method combined with microcanonical
simulations and finite-size scaling analysis to estimate the critical
temperature and critical exponents of this system with little computational
effort. In addition, we present a general procedure which makes possible to use
the broad histogram method for continuous systems, also when the macroscopic
quantities needed by the method cannot be obtained analytically. Our results
are robust under the choice of four different pseudo-random number generators.
