ResidualFunctionAdapter.h

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// ************************************************************************** //
//
//  BornAgain: simulate and fit scattering at grazing incidence
//
//! @file      Fit/RootAdapter/ResidualFunctionAdapter.h
//! @brief     Defines class ResidualFunctionAdapter.
//!
//! @homepage  http://www.bornagainproject.org
//! @license   GNU General Public License v3 or higher (see COPYING)
//! @copyright Forschungszentrum Jülich GmbH 2018
//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
//
// ************************************************************************** //
 
#ifndef BORNAGAIN_FIT_ROOTADAPTER_RESIDUALFUNCTIONADAPTER_H
#define BORNAGAIN_FIT_ROOTADAPTER_RESIDUALFUNCTIONADAPTER_H
 
#include "Fit/Kernel/IFunctionAdapter.h"
#include "Fit/Kernel/KernelTypes.h"
#include "Fit/Kernel/Parameters.h"
#include <functional>
#include <memory>
#include <vector>
 
class RootResidualFunction;
 
namespace Fit
{
 
//! Provides RootResidualFunction which will be minimizer by ROOT.
//! Converts ROOT calls to the call of fcn_residual_t.
 
class ResidualFunctionAdapter : public IFunctionAdapter
{
public:
    ResidualFunctionAdapter(fcn_residual_t func, const Parameters& parameters);
 
    const RootResidualFunction* rootResidualFunction();
 
private:
    void calculate_gradients(const std::vector<double>& pars);
    std::vector<double> get_residuals(const std::vector<double>& pars);
 
    //! evaluate method for gradients and residuals called directly from the minimizer
    double element_residual(const std::vector<double>& pars, unsigned int index,
                            std::vector<double>& gradients);
    //! Evaluate chi2
    double chi2(const std::vector<double>& pars);
 
    //! Length of vector with residuals, should stay the same during minimization.
    size_t m_datasize;
    fcn_residual_t m_fcn; //!< user function to minimize
    Parameters m_parameters;
    std::vector<double> m_residuals;
    std::vector<std::vector<double>> m_gradients; // [m_npars][m_ndatasize]
    std::unique_ptr<RootResidualFunction> m_root_objective;
};
 
} //  namespace Fit
 
#endif // BORNAGAIN_FIT_ROOTADAPTER_RESIDUALFUNCTIONADAPTER_H