  A general formalism for the evaluation of time reversal odd parton
distributions is applied here to calculate the Boer-Mulders function. The same
formalism when applied to evaluate the Sivers function led to results which
fulfill the Burkardt sum rule quite well. The calculation here has been
performed for two different models of proton structure: a constituent quark
model and the MIT bag model. In the latter case, important differences are
found with respect to a previous evaluation in the same framework, a feature
already encountered in the calculation of the Sivers function. The results
obtained are consistent with the present wisdom, i.e., the contributions for
the $u$ and $d$ flavors turn out to have the same sign, following the pattern
suggested analyzing the model independent features of the impact parameter
dependent generalized parton distributions. It is therefore confirmed that the
present approach is suitable for the analysis of time reversal odd distribution
functions. A critical comparison between the outcomes of the two models, as
well as between the results of the calculations for the Sivers and Boer-Mulders
functions, is also carried out.
