  We present a systematic study of the pure deflagration model of Type Ia
supernovae using three-dimensional, high-resolution, full-star hydrodynamical
simulations, nucleosynthetic yields calculated using Lagrangian tracer
particles, and light curves calculated using radiation transport. We evaluate
the simulations by comparing their predicted light curves with many observed
SNe Ia using the SALT2 data-driven model and find that the simulations may
correspond to under-luminous SNe Iax. We explore the effects of the initial
conditions on our results by varying the number of randomly selected ignition
points from 63 to 3500, and the radius of the centered sphere they are confined
in from 128 to 384 km. We find that the rate of nuclear burning depends on the
number of ignition points at early times, the density of ignition points at
intermediate times, and the radius of the confining sphere at late times. The
results depend primarily on the number of ignition points, but we do not expect
this to be the case in general. The simulations with few ignition points
release more nuclear energy $E_{\mathrm{nuc}}$, have larger kinetic energies
$E_{\mathrm{K}}$, and produce more $^{56}$Ni than those with many ignition
points, and differ in the distribution of $^{56}$Ni, Si, and C/O in the ejecta.
For these reasons, the simulations with few ignition points exhibit higher peak
B-band absolute magnitudes $M_\mathrm{B}$ and light curves that rise and
decline more quickly; their $M_\mathrm{B}$ and light curves resemble those of
under-luminous SNe Iax, while those for simulations with many ignition points
are not.
