/usr/include/shark/Rng/Geometric.h is in libshark-dev 3.0.1+ds1-2ubuntu1.
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*
*
* \brief Implements a 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_GEOMETRIC_H
#define SHARK_RNG_GEOMETRIC_H
#include <cmath>
namespace shark{
/**
* \brief Implements the geometric distribution.
*
* Note that a support {1,2,3,...} is assumed here.
*/
template<typename RngType = shark::DefaultRngType>
class Geometric:public boost::variate_generator<RngType*,boost::geometric_distribution<long> > {
private:
typedef boost::variate_generator<RngType*,boost::geometric_distribution<long> > Base;
public:
/**
* \brief C'tor, initializes the parameter p modelling the probability of success. Associates
* the distribution with a custom RNG.
* \param [in,out] rng The RNG to associate the distribution with.
* \param [in] p Parameter p, the probability of success.
*/
Geometric( RngType & rng, double p = 0.5 )
:Base(&rng,boost::geometric_distribution<long>(1.0-p))
{}
/** \brief Injects the default sampling operator. */
using Base::operator();
/**
* \brief Reinitializes the distribution with the supplied success probability and samples a random number.
* \param [in] p The new success probability.
*/
long operator()(double p) {
boost::geometric_distribution<long> dist( p );
return dist(Base::engine());
}
/**
* \brief Accesses the success probability.
*/
double prob() const {
return 1-Base::distribution().p();
}
/**
* \brief Adjusts the success probability.
*/
void prob(double newMean) {
Base::distribution()=boost::geometric_distribution<long>(1-newMean);
}
/**
* \brief Calculates the probability of x.
*/
double p( long x ) {
return( x > 0 ? prob() * std::pow(1 - prob(), (double) x - 1) : 0 );
}
};
}
#endif
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