MPRVFIT is an IDL based procedure for fitting Keplerian models to radial velocity data. It was developed as part of the SDSS-III MARVELS radial velocity survey. The primary purpose of MPRVFIT is to provide a fast first pass Keplerian fit to a large number of radial velocity curves. It starts by generating a Lomb-Scargle periodogram, and selects out a specified number of periodogram peaks. It then runs a Levenberg-Marquardt non-linear least sqaures fitter to determine the best orbital elements. The MPRVFIT procedure contains a complete header detailing the available options, and providing examples. For more details consult De Lee et al. (2013, submitted). The procedure can be downloaded here.
The above images show output from MPRVFIT.PRO when run on radial velocity data from the host star of MARVELS-6b (De Lee et al. 2013). The output includes a Lomb-Scargle periodogram, unphased and phased Keplerian fits, and a residual plot.