RandomGenerator.cpp

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/*
 *  CepGen: a central exclusive processes event generator
 *  Copyright (C) 2023-2024  Laurent Forthomme
 *
 *  This program 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
 *  any later version.
 *
 *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <TRandom1.h>
#include <TRandom2.h>
#include <TRandom3.h>
#include <TRandomGen.h>
 
#include <memory>
 
#include "CepGen/Core/Exception.h"
#include "CepGen/Modules/RandomGeneratorFactory.h"
#include "CepGen/Utils/RandomGenerator.h"
 
namespace cepgen {
  namespace root {
    class RandomGenerator : public utils::RandomGenerator {
    public:
      explicit RandomGenerator(const ParametersList& params) : utils::RandomGenerator(params) {
        const auto& type = steer<std::string>("type");
        if (type == "Ranlux")
          rng_.reset(new TRandom1);
        else if (type == "Tausworthe")
          rng_.reset(new TRandom2);
        else if (type == "MersenneTwister")
          rng_.reset(new TRandom3);
        else if (type == "Ranluxpp")
          rng_.reset(new TRandomRanluxpp);
        else if (type == "MixMax")
          rng_.reset(new TRandomMixMax);
        else if (type == "MixMax17")
          rng_.reset(new TRandomMixMax17);
        else if (type == "MixMax256")
          rng_.reset(new TRandomMixMax256);
        else
          throw CG_FATAL("root:RandomGenerator") << "Random number generator engine invalid: '" << type << "'.";
 
        rng_->SetSeed(seed_);
      }
 
      static ParametersDescription description() {
        auto desc = utils::RandomGenerator::description();
        desc.setDescription("ROOT random number generator engine");
        desc.add<std::string>("type", "Ranlux")
            .setDescription("random number engine")
            .allow("Ranlux")
            .allow("Tausworthe")
            .allow("MersenneTwister")
            .allow("Ranluxpp")
            .allow("MixMax")
            .allow("MixMax17")
            .allow("MixMax256");
        return desc;
      }
 
      int uniformInt(int min, int max) override { return min + rng_->Integer(max - min + 1); }
      double uniform(double min, double max) override { return rng_->Uniform(min, max); }
      double normal(double mean, double rms) override { return rng_->Gaus(mean, rms); }
      double exponential(double exponent) override { return rng_->Exp(exponent); }
      double breitWigner(double mean, double scale) override { return rng_->BreitWigner(mean, scale); }
      double landau(double location, double width) override { return rng_->Landau(location, width); }
      int poisson(double mean) override { return rng_->Poisson(mean); }
 
    private:
      void* enginePtr() override { return rng_.get(); }
      std::unique_ptr<TRandom> rng_;
    };
  }  // namespace root
}  // namespace cepgen
using ROOTRandomGenerator = cepgen::root::RandomGenerator;
REGISTER_RANDOM_GENERATOR("root", ROOTRandomGenerator);