  The general context of this study is the inversion of stellar fundamental
parameters from high-resolution Echelle spectra. We aim indeed at developing a
fast and reliable tool for the post-processing of spectra produced by Espadons
and Narval spectropolarimeters. Our inversion tool relies on principal
component analysis. It allows reduction of dimensionality and the definition of
a specific metric for the search of nearest neighbours between an observed
spectrum and a set of observed spectra taken from the Elodie stellar library.
Effective temperature, surface gravity, total metallicity and projected
rotational velocity are derived. Various tests presented in this study, and
done from the sole information coming from a spectral band centered around the
Mg I b-triplet and with spectra from FGK stars are very promising.
