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//
// INCL++ intra-nuclear cascade model
// Pekka Kaitaniemi, CEA and Helsinki Institute of Physics
// Davide Mancusi, CEA
// Alain Boudard, CEA
// Sylvie Leray, CEA
// Joseph Cugnon, University of Liege
//
#define INCLXX_IN_GEANT4_MODE 1

#include "globals.hh"

/** \file G4INCLIFunction1D.hh
 * \brief Functor for 1-dimensional mathematical functions
 *
 * \date 16 July 2012
 * \author Davide Mancusi
 */

#ifndef G4INCLIFUNCTION1D_HH_
#define G4INCLIFUNCTION1D_HH_ 1

#include <vector>

namespace G4INCL {

  // Forward declaration
  class InverseInterpolationTable;

  /**
   * 1D function interface
   */
  class IFunction1D {
    public:
      IFunction1D() :
        xMin(0.),
        xMax(0.)
    {};
      IFunction1D(const G4double x0, const G4double x1) :
        xMin(x0),
        xMax(x1)
    {};

      virtual ~IFunction1D() {};

      /// \brief Return the minimum allowed value of the independent variable
      virtual inline G4double getXMinimum() const { return xMin; }

      /// \brief Return the maximum allowed value of the independent variable
      virtual inline G4double getXMaximum() const { return xMax; }

      /// \brief Compute the value of the function
      virtual G4double operator()(const G4double x) const = 0;

      /** \brief Integrate the function between two values
       *
       * \param x0 lower integration bound
       * \param x1 upper integration bound
       * \param step largest integration step size; if <0, 45 steps will be used
       * \return \f$\int_{x_0}^{x_1} f(x) dx\f$
       */
      virtual G4double integrate(const G4double x0, const G4double x1, const G4double step=-1.) const;

      /// \brief Return a pointer to the (numerical) primitive to this function
      IFunction1D *primitive() const;

      /// \brief Return a pointer to the inverse of the CDF of this function
      InverseInterpolationTable *inverseCDFTable(const G4int nNodes=60) const;

    protected:
      /// \brief Minimum value of the independent variable
      G4double xMin;
      /// \brief Maximum value of the independent variable
      G4double xMax;

    private:
      /// \brief Coefficients for numerical integration
      static const G4double integrationCoefficients[];
  };

}

#endif // G4INCLIFUNCTION1D_HH_