  In this paper, we select a sample of quiescent luminous red galaxies (LRGs)
from Sloan Digital Sky Survey Data Release 7 (SDSS DR7) with signal-to-noise
ratio (S/N) substantially high to study the consistency of the full spectrum
fitting method by using different packages, mainly, ULySS and STARLIGHT. The
spectrum of each galaxy in the sample is fitted by the full spectrum fitting
packages ULySS and STARLIGHT, respectively. We find: (1) for spectra with
higher S/Ns, the ages of stellar populations obtained from ULySS are slightly
older than that from STARLIGHT, and metallicities derived from ULySS are
slightly richer than that from STARLIGHT. In general, both packages can give
roughly consistent fitting results. (2) for low S/N spectra, it is possible
that the fitting by ULySS can be trapped some local minimum parametric regions
during execution and thus may give unreliable results, while STARLIGHT can
still give reliable results. Based on the fitting results of LRGs, we further
analyse their star formation history (SFH) and the relation between their age
and velocity dispersion, and find that those highly agrees with conclusions
from others' previous work.
