Calculation of binary-star orbits is simple with modern computers, and several such codes can be found. The FORTRAN code ORBITX for calculation of visual, spectroscopic, or combined visual-spectroscopic orbits has been used in the 1990-s. I adapted it to IDL now. It can plot the orbit and the data on the sky or in radial velocity, adjust orbital elements by differential corrections, and do some auxiliary service like ephemeris.
Reference for ORBITX: Tokovinin A. Speckle-spectroscopic studies of late-type stars. Proc. IAU Coll. 135, Ed. H.A. McAlister and W.I. Hartkopf. ASP Conf. Ser., 1992, V.32, P. 573-576.
Get the code [tar.gz] and use it at your own risk. The distribution contains examples of data files and the short Instruction on the data format and use. The code can be further adapted, starting from this example.
The code is posted on ZENODO: http://dx.doi.org/10.5281/zenodo.61119
ORBIT3.PRO for fitting triple stars: orbit3.tar.gz
on ZENODO: http://dx.doi.org/10.5281/zenodo.321854
Last change: Feb 23, 2017. A. Tokovinin