GLATPsfV3.hpp

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/***************************************************************************
 *     GLATPsfV3.hpp - Fermi/LAT point spread function version 3 class     *
 * ----------------------------------------------------------------------- *
 *  copyright (C) 2012-2014 by Juergen Knoedlseder                         *
 * ----------------------------------------------------------------------- *
 *                                                                         *
 *  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/>.  *
 *                                                                         *
 ***************************************************************************/
/**
 * @file GLATPsfV3.hpp
 * @brief Fermi/LAT point spread function version 3 class definition
 * @author Juergen Knoedlseder
 */
 
#ifndef GLATPSFV3_HPP
#define GLATPSFV3_HPP
 
/* __ Includes ___________________________________________________________ */
#include <vector>
#include <cmath>
#include "GLATPsfBase.hpp"
#include "GFits.hpp"
#include "GFitsTable.hpp"
#include "GFunction.hpp"
 
 
/***********************************************************************//**
 * @class GLATPsfV3
 *
 * @brief Fermi/LAT point spread function version 3 class
 *
 * Version 3 of the Fermi/LAT PSF is the sum of two King model functions.
 * In contrast to version 2, this class interpolates the distributions
 * rather than the parameters.
 *
 * This class has been inspired by code from the Fermi/LAT ScienceTools.
 * For comparison check the file irfs/latResponse/src/Psf3.h
 ***************************************************************************/
class GLATPsfV3 : public GLATPsfBase {
 
public:
    // Constructors and destructors
    GLATPsfV3(void);
    GLATPsfV3(const GLATPsfV3& psf);
    virtual ~GLATPsfV3(void);
 
    // Operators
    GLATPsfV3& operator=(const GLATPsfV3& psf);
 
    // Methods
    void        clear(void);
    GLATPsfV3*  clone(void) const;
    std::string classname(void) const;
    void        read(const GFitsTable& table);
    void        write(GFits& file) const;
    double      psf(const double& offset, const double& logE,
                    const double& ctheta);
    int         version(void) const;
    std::string print(const GChatter& chatter = NORMAL) const;
 
private:
    // Methods
    void          init_members(void);
    void          copy_members(const GLATPsfV3& psf);
    void          free_members(void);
    static double base_fct(const double& u, const double& gamma);
    static double base_int(const double& u, const double& gamma);
    double        eval_psf(const double& offset, const double& energy,
                           const int& index);
    double        integrate_psf(const double& energy, const int& index);
    void          normalize_psf(void);
 
    // Integrand class. This class is used to perform the radial
    // integration of the PSF to assure the proper normalization.
    // Note that score and stail need to be scaled by energy.
    class base_integrand : public GFunction {
    public:
        base_integrand(double ncore, double ntail,
                       double score, double stail,
                       double gcore, double gtail) :
                       m_ncore(ncore), m_ntail(ntail),
                       m_score(score), m_stail(stail),
                       m_gcore(gcore), m_gtail(gtail) { }
        double eval(const double& x) {
            double rc = x / m_score;
            double uc = 0.5 * rc * rc;
            double rt = x / m_stail;
            double ut = 0.5 * rt * rt;
            double f = m_ncore * (base_fct(uc, m_gcore) + 
                                  m_ntail * base_fct(ut, m_gtail));
            return (f*std::sin(x));
        }
    private:
        double m_ncore;
        double m_ntail;
        double m_score;
        double m_stail;
        double m_gcore;
        double m_gtail;
    };
    
    // Protected members
    std::vector<double> m_ncore;        //!< PSF ncore parameter
    std::vector<double> m_ntail;        //!< PSF ntail parameter
    std::vector<double> m_score;        //!< PSF score parameter
    std::vector<double> m_stail;        //!< PSF stail parameter
    std::vector<double> m_gcore;        //!< PSF gcore parameter
    std::vector<double> m_gtail;        //!< PSF gtail parameter
};
 
 
/***********************************************************************//**
 * @brief Return class name
 *
 * @return String containing the class name ("GLATPsfV3").
 ***************************************************************************/
inline
std::string GLATPsfV3::classname(void) const
{
    return ("GLATPsfV3");
}
 
 
/***********************************************************************//**
 * @brief Return point spread function version number
 *
 * @return Point spread function version number (3).
 ***************************************************************************/
inline
int GLATPsfV3::version(void) const
{
    return 3;
}
 
#endif /* GLATPSFV3_HPP */