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// ************************************************************************************************
//
// BornAgain: simulate and fit reflection and scattering
//
//! @file Fit/Residual/RootResidualFunction.cpp
//! @brief Implements class RootResidualFunction.
//!
//! @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)
//
// ************************************************************************************************
#include "Fit/Residual/RootResidualFunction.h"
#include <utility>
RootResidualFunction::RootResidualFunction(const scalar_function_t& objective_fun,
const gradient_function_t& gradient_fun, size_t npars,
size_t ndatasize)
: ROOT::Math::FitMethodFunction(static_cast<int>(npars), static_cast<int>(ndatasize))
, m_objective_fun(objective_fun)
, m_gradient_fun(gradient_fun)
, m_npars(npars)
, m_datasize(ndatasize)
{
}
RootResidualFunction::Type_t RootResidualFunction::Type() const
{
return ROOT::Math::FitMethodFunction::kLeastSquare;
}
ROOT::Math::IMultiGenFunction* RootResidualFunction::Clone() const
{
return new RootResidualFunction(m_objective_fun, m_gradient_fun, m_npars, m_datasize);
}
//! Returns residual value for given data element index. Transform call of ancient
//! pointer based function to safer gradient_function_t.
//! @param pars: array of fit parameter values from the minimizer
//! @param index: index of residual element
//! @param gradients: if not zero, then array where we have to put gradients
//! @return value of residual for given data element index
double RootResidualFunction::DataElement(const double* pars, unsigned int index,
double* gradients) const
{
std::vector<double> par_values;
par_values.resize(m_npars, 0.0);
std::copy(pars, pars + m_npars, par_values.begin());
std::vector<double> par_gradients;
if (gradients)
par_gradients.resize(m_npars);
// retrieving result from user function
double result = m_gradient_fun(par_values, index, par_gradients);
// packing result back to minimizer's array
if (gradients)
for (size_t i = 0; i < m_npars; ++i)
gradients[i] = par_gradients[i];
return result;
}
double RootResidualFunction::DoEval(const double* pars) const
{
std::vector<double> par_values;
par_values.resize(m_npars, 0.0);
std::copy(pars, pars + m_npars, par_values.begin());
return m_objective_fun(par_values);
}
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