/*
  *  MoMEMta: a modular implementation of the Matrix Element Method
  *  Copyright (C) 2016  Universite catholique de Louvain (UCL), Belgium
  *
  *  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
  *  (at your option) 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 <momemta/ParameterSet.h>
 #include <momemta/Module.h>
 
 #include <cmath>
 
 class NarrowWidthApproximation: public Module {
     public:
 
         NarrowWidthApproximation(PoolPtr pool, const ParameterSet& parameters): Module(pool, parameters.getModuleName())
         {
             double mass = parameters.get<double>("mass");
             double width = parameters.get<double>("width");
 
             *jacobian = M_PI;
             if(parameters.get<bool>("propagator_in_me", true))
                 *jacobian *= mass*width;
             else
                 *jacobian /= mass*width;
 
             *s = mass*mass;
         }
 
     private:
 
         std::shared_ptr<double> s = produce<double>("s");
         std::shared_ptr<double> jacobian = produce<double>("jacobian");
 };
 
 REGISTER_MODULE(NarrowWidthApproximation)
         .Output("s")
         .Output("jacobian")
         .Attr("mass:double")
         .Attr("width:double")
         .Attr("propagator_in_me:bool=true");