GCTAModelRadialGauss.hpp

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/***************************************************************************
 *       GCTAModelRadialGauss.hpp - Radial Gaussian CTA model class        *
 * ----------------------------------------------------------------------- *
 *  copyright (C) 2011-2018 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 GCTAModelRadialGauss.hpp
 * @brief Radial Gaussian model class interface definition
 * @author Juergen Knoedlseder
 */

#ifndef GCTAMODELRADIALGAUSS_HPP
#define GCTAMODELRADIALGAUSS_HPP

/* __ Includes ___________________________________________________________ */
#include <string>
#include <cmath>
#include "GModelPar.hpp"
#include "GCTAModelRadial.hpp"
#include "GFunction.hpp"

/* __ Forward declarations _______________________________________________ */
class GRan;
class GXmlElement;
class GCTAObservation;
class GCTAInstDir;


/***********************************************************************//**
 * @class GCTAModelRadialGauss
 *
 * @brief Radial Gaussian CTA model class
 *
 * This class implements the radial function
 * \f[f(\theta) = \exp \left(-\frac{1}{2}
 *                     \left( \frac{\theta^2}{\sigma} \right)^2 \right)\f]
 * where
 * \f$\theta\f$ is the offset angle (in degrees), and
 * \f$\sigma\f$ is the width parameter (in degrees\f$^2\f$).
 *
 * This function represents a Gaussian in \f$\theta^2\f$.
 ***************************************************************************/
class GCTAModelRadialGauss  : public GCTAModelRadial {

public:
    // Constructors and destructors
    GCTAModelRadialGauss(void);
    explicit GCTAModelRadialGauss(const double& sigma);
    explicit GCTAModelRadialGauss(const GXmlElement& xml);
    GCTAModelRadialGauss(const GCTAModelRadialGauss& model);
    virtual ~GCTAModelRadialGauss(void);

    // Operators
    virtual GCTAModelRadialGauss& operator= (const GCTAModelRadialGauss& model);

    // Implemented pure virtual methods
    virtual void                  clear(void);
    virtual GCTAModelRadialGauss* clone(void) const;
    virtual std::string           classname(void) const;
    virtual std::string           type(void) const;
    virtual double                eval(const double& offset,
                                       const bool& gradients = false) const;
    virtual GCTAInstDir           mc(GRan& ran) const;
    virtual double                mc_max_value(const GCTAObservation& obs) const;
    virtual double                omega(void) const;
    virtual void                  read(const GXmlElement& xml);
    virtual void                  write(GXmlElement& xml) const;
    virtual std::string           print(const GChatter& chatter = NORMAL) const;

    // Other methods
    double sigma(void) const;
    void   sigma(const double& sigma);

protected:
    // Protected methods
    void init_members(void);
    void copy_members(const GCTAModelRadialGauss& model);
    void free_members(void);

    // Radial integration class (used by omega() method). Note that the
    // sigma parameter is given in rad^2
    class integrand : public GFunction {
    public:
        integrand(double sigma) : m_sigma(sigma) { }
        double eval(const double& x) {
            double arg  = x * x / m_sigma;
            double arg2 = arg * arg;
            double f    = std::exp(-0.5 * arg2);
            return (f*std::sin(x));
        }
    private:
        double m_sigma;
    };

    // Protected members
    GModelPar m_sigma;        //!< Width parameter (degrees^2)
};


/***********************************************************************//**
 * @brief Return class name
 *
 * @return String containing the class name ("GCTAModelRadialGauss").
 ***************************************************************************/
inline
std::string GCTAModelRadialGauss::classname(void) const
{
    return ("GCTAModelRadialGauss");
}


/***********************************************************************//**
 * @brief Return model type
 *
 * @return Model type "Gaussian".
 ***************************************************************************/
inline
std::string GCTAModelRadialGauss::type(void) const
{
    return ("Gaussian");
}


/***********************************************************************//**
 * @brief Return Gaussian width parameter
 *
 * @return Gaussian width parameter.
 ***************************************************************************/
inline
double GCTAModelRadialGauss::sigma(void) const
{
    return (m_sigma.value());
}


/***********************************************************************//**
 * @brief Set Gaussian width parameter
 *
 * @param[in] sigma Gaussian width parameter.
 ***************************************************************************/
inline
void GCTAModelRadialGauss::sigma(const double& sigma)
{
    m_sigma.value(sigma);
    return;
}

#endif /* GCTAMODELRADIALGAUSS_HPP */