  We present a comprehensive spectral analysis of black hole X-ray binaries,
LMC X-1 and LMC X-3, based on BeppoSAX observations. We test both the
multi-color disk plus power law (MCD+PL) model and a newly-developed
Monte-Carlo simulation- based model for a Comptonized MCD (CMCD) with either a
spherical or a slab-like corona, by comparing the inferred parameters with
independent direct measurements. While all models give an adequate description
of the spectra, we find a significant discrepancy between the MCD+PL inferred
X-ray-absorbing gas column density and the absorption-edge measurement based on
dispersed X-ray spectra. The MCD+PL fits to the LMC X-1 spectra also require a
change in the inner disk radius during the BeppoSAX observation, which may be
due to the nonphysical effects inherited in the model. In contrast, the CMCD
model with the spheric corona gives the predictions of both the disk
inclination angle and the absorption that are consistent with the direct
measurements, and only slightly under-predicts the black hole mass of LMC X-3.
The model explains the spectral state evolution of LMC X-1 within the BeppoSAX
observation as a change in the accretion rate, which leads to an increase in
both the inner disk temperature and the Comptonization opacity. On the other
hand, the CMCD model with the slab-like corona is more problematic in the test
and is thus not recommended.
