  We present PlanetPack, a new software tool that we developed to facilitate
and standardize the advanced analysis of radial velocity (RV) data for the goal
of exoplanets detection, characterization, and basic dynamical $N$-body
simulations. PlanetPack is a command-line interpreter, that can run either in
an interactive mode or in a batch mode of automatic script interpretation.
  Its major abilities include: (i) Advanced RV curve fitting with the proper
maximum-likelihood treatment of unknown RV jitter; (ii) User-friendly
multi-Keplerian as well as Newtonian $N$-body RV fits; (iii) Use of more
efficient maximum-likelihood periodograms that involve the full multi-planet
fitting (sometimes called as ``residual'' or ``recursive'' periodograms); (iv)
Easily calculatable parametric 2D likelihood function level contours,
reflecting the asymptotic confidence regions; (v) Fitting under some useful
functional constraints is user-friendly; (vi) Basic tasks of short- and
long-term planetary dynamical simulation using a fast Everhart-type integrator
based on Gauss--Legendre spacings; (vii) Fitting the data with red noise
(auto-correlated errors); (viii) Various analytical and numerical methods for
the tasks of determining the statistical significance.
  It is planned that further functionality may be added to PlanetPack in the
future. During the development of this software, a lot of effort was made to
improve the calculational speed, especially for CPU-demanding tasks. PlanetPack
was written in pure C++ (standard of 1998/2003), and is expected to be
compilable and usable on a wide range of platforms.
