/usr/include/shark/Rng/DiffGeometric.h is in libshark-dev 3.0.1+ds1-2ubuntu1.
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*
*
* \brief Diff geometric distribution.
*
*
*
* \author O. Krause
* \date 2010-01-01
*
*
* \par Copyright 1995-2015 Shark Development Team
*
* <BR><HR>
* This file is part of Shark.
* <http://image.diku.dk/shark/>
*
* Shark is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Shark 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Shark. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef SHARK_RNG_DIFFGEOMETRIC_H
#define SHARK_RNG_DIFFGEOMETRIC_H
#include <shark/Rng/Rng.h>
#include <boost/random.hpp>
#include <boost/random/geometric_distribution.hpp>
#ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
#include <iostream>
#endif
#include <cmath>
namespace shark{
/**
* \brief Implements a diff geometric distribution.
*/
template<class IntType = int, class RealType = double>
class DiffGeometric_distribution
{
public:
typedef RealType input_type;
typedef IntType result_type;
explicit DiffGeometric_distribution(const RealType& p = RealType(0.5))
:geom(p) {}
RealType p() const
{
return geom.p();
}
void reset() { }
template<class Engine>
result_type operator()(Engine& eng)
{
return geom(eng)-geom(eng);
}
#ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
template<class CharT, class Traits>
friend std::basic_ostream<CharT,Traits>&
operator<<(std::basic_ostream<CharT,Traits>& os, const DiffGeometric_distribution& gd)
{
os << gd.geom;
return os;
}
template<class CharT, class Traits>
friend std::basic_istream<CharT,Traits>&
operator>>(std::basic_istream<CharT,Traits>& is, DiffGeometric_distribution& gd)
{
is >> gd.geom;
return is;
}
#endif
private:
boost::geometric_distribution<IntType,RealType> geom;
};
/**
* \brief Random variable with diff geometric distribution.
*/
template<typename RngType = shark::DefaultRngType>
class DiffGeometric: public boost::variate_generator<RngType*,DiffGeometric_distribution<> >
{
private:
typedef boost::variate_generator<RngType*,DiffGeometric_distribution<> > Base;
public:
DiffGeometric( RngType & rng, double mean = 0.5 )
:Base(&rng,DiffGeometric_distribution<>(1.0-mean))
{}
using Base::operator();
double operator()(double mean)
{
DiffGeometric_distribution<> dist(mean);
return dist(Base::engine());
}
double mean()const
{
return 1-Base::distribution().p();
}
void mean(double newMean)
{
Base::distribution()=DiffGeometric_distribution<>(1-newMean);
}
double p(double x)const
{
return( mean() * std::pow( 1 - mean(), std::abs(x) ) / ( 2 - mean() ) );
}
};
}
#endif
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