File: src/rho.cc
  The C++ code for the rho functions is based on the C code distributed with
  the R package robustbase_0.92-5 with Copyright (C)
    * Peter Rousseeuw and Christophe Croux;
    * Valentin Todorov <valentin.todorov@chello.at>
    * Andreas Ruckstuhl <andreas.ruckstuhl@zhaw.ch>
    * Matias Salibian-Barrera <matias@stat.ubc.ca>
    * Tobias Verbeke <tobias.verbeke@openanalytics.eu>
    * Manuel Koller <mkoller@ispm.unibe.ch>
    * Martin Maechler <maechler@stat.math.ethz.ch>
