GammaDiscreteDistribution.h

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// SPDX-FileCopyrightText: The Bio++ Development Group
//
// SPDX-License-Identifier: CECILL-2.1

#ifndef BPP_NUMERIC_PROB_GAMMADISCRETEDISTRIBUTION_H
#define BPP_NUMERIC_PROB_GAMMADISCRETEDISTRIBUTION_H


#include "../Constraints.h"
#include "../Random/RandomTools.h"
#include "AbstractDiscreteDistribution.h"

namespace bpp
{
class GammaDiscreteDistribution :
  public AbstractDiscreteDistribution
{
private:
  double alpha_, beta_;

  double offset_;

  // To prevent useless computations
  double ga1_;

public:
  std::string getName() const {return "Gamma";}

  GammaDiscreteDistribution(size_t n, double alpha = 1., double beta = 1., double minimumAlpha = 0.05, double minimumBeta = 0.05, bool paramOffset = false, double offset = 0);

  GammaDiscreteDistribution(const GammaDiscreteDistribution&);

  GammaDiscreteDistribution& operator=(const GammaDiscreteDistribution&);

  virtual ~GammaDiscreteDistribution();

  GammaDiscreteDistribution* clone() const { return new GammaDiscreteDistribution(*this); }

  void fireParameterChanged(const ParameterList& parameters);

  double randC() const
  {
    double x = RandomTools::randGamma(getParameterValue("alpha"),
          getParameterValue("beta"));
    while (!intMinMax_->isCorrect(x))
      x = RandomTools::randGamma(getParameterValue("alpha"),
            getParameterValue("beta"));

    return x + offset_;
  }

  double qProb(double x) const;

  double pProb(double x) const;

  double Expectation(double a) const;
};
} // end of namespace bpp.
#endif // BPP_NUMERIC_PROB_GAMMADISCRETEDISTRIBUTION_H