integrator.h

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//
// APFEL++ 2017
//
// Author: Valerio Bertone: valerio.bertone@cern.ch
//
 
#pragma once
 
#include <functional>
#include <vector>
 
namespace apfel
{
  class Integrator
  {
  public:
    enum IntegrationMethod: int {GAUSS_LEGENDRE, GAUSS_KRONROD};
 
 
    Integrator(std::function<double(double const&)> const& func, IntegrationMethod const& method = GAUSS_KRONROD);
 
    double integrate(double const& xmin, double const& xmax, double const& eps) const;
 
    double integrate(double const& xmin, double const& xmax, std::vector<double> const& FixPts, double const& eps) const;
 
    double integrate(std::vector<double> const& FixPts, double const& eps) const;
 
    double integrate(double const& xmin, double const& xmax, int const& n = 1) const;
 
    double integrate(double const& xmin, double const& xmax, std::vector<double> const& FixPts, int const& n = 1) const;
 
    double integrate(std::vector<double> const& FixPts, int const& n = 1) const;
 
    double integrand(double const& x) const { return _func(x); };
 
    IntegrationMethod Method() const { return _method; };
 
  private:
    std::pair<double, double> integrateGL(double const& xmin, double const& xmax) const;
 
    std::pair<double, double> integrateGK(double const& xmin, double const& xmax) const;
 
    double integrateGL(double const& xmin, double const& xmax, int const& n) const;
 
    double integrateGK(double const& xmin, double const& xmax, int const& n) const;
 
  private:
    std::function<double(double const&)> const _func;   
    IntegrationMethod                    const _method; 
  };
}