source: trunk/yat/regression/TukeyBiweight.h @ 2508

#ifndef _theplu_yat_regression_tukey_biweight_
#define _theplu_yat_regression_tukey_biweight_

// $Id: TukeyBiweight.h 2508 2011-07-08 20:56:29Z peter $

/*
  Copyright (C) 2011 Peter Johansson

  This file is part of the yat library, http://dev.thep.lu.se/yat

  The yat library is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 3 of the
  License, or (at your option) any later version.

  The yat library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with yat. If not, see <http://www.gnu.org/licenses/>.
*/

#include "Kernel.h"

namespace theplu {
namespace yat {
namespace regression {

  /**
     Functor returning \f$ (1-x^2)^2 \f$ if |x|<1 and 0 otherwise.
   */
  class TukeyBiweight : public Kernel
  {
  public:
    /**
       \return \f$ (1-x^2)^2 \f$ if |x|<1 and 0 otherwise.
     */
    double operator()(const double x) const;
  };

}}} // of namespaces regression, yat, and theplu

#endif