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Poisson.cpp

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/*******************************************************************************
 * This file is part of openWNS (open Wireless Network Simulator)
 * _____________________________________________________________________________
 *
 * Copyright (C) 2004-2007
 * Chair of Communication Networks (ComNets)
 * Kopernikusstr. 16, D-52074 Aachen, Germany
 * phone: ++49-241-80-27910,
 * fax: ++49-241-80-22242
 * email: info@openwns.org
 * www: http://www.openwns.org
 * _____________________________________________________________________________
 *
 * openWNS is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License version 2 as published by the
 * Free Software Foundation;
 *
 * openWNS 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
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#include <WNS/distribution/Poisson.hpp>

#include <WNS/module/Base.hpp>

using namespace wns::distribution;

STATIC_FACTORY_REGISTER_WITH_CREATOR(
    Poisson,
    Distribution,
    "Poisson",
    wns::PyConfigViewCreator);
STATIC_FACTORY_REGISTER_WITH_CREATOR(
    Poisson,
    Distribution,
    "Poisson",
    wns::distribution::RNGConfigCreator);

Poisson::Poisson(double mean, wns::rng::RNGen* rng) :
    Distribution(rng),
    mean_(mean),
    dis_(getRNG())
{
}

Poisson::Poisson(const pyconfig::View& config) :
    Distribution(),
    mean_(config.get<double>("mean")),
    dis_(getRNG())
{
}

Poisson::Poisson(wns::rng::RNGen* rng, const pyconfig::View& config) :
    Distribution(rng),
    mean_(config.get<double>("mean")),
    dis_(getRNG())
{
}


Poisson::~Poisson()
{
}


double
Poisson::operator()()
{
    double product;
    double bound = exp(-1.0 * mean_);
    int16_t i = 0;
    
    for (product = 1.0; product >= bound; product *= dis_())
    {
        i++;
    }
    return i - 1;
}


double
Poisson::getMean() const
{
    return mean_;
}


std::string
Poisson::paramString() const
{
    std::ostringstream tmp;
    tmp << "Poisson(mean=" << this->getMean() <<")";
    return tmp.str();
}

/*
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  End:
*/

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