FCNGradAdapter.h

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// @(#)root/minuit2:$Id$
// Author: L. Moneta    10/2006
 
/**********************************************************************
 *                                                                    *
 * Copyright (c) 2006 ROOT Foundation,  CERN/PH-SFT                   *
 *                                                                    *
 **********************************************************************/
 
#ifndef ROOT_Minuit2_FCNGradAdapter
#define ROOT_Minuit2_FCNGradAdapter
 
#include "Minuit2/FCNGradientBase.h"
#include "Minuit2/MnPrint.h"
 
#include <vector>
 
namespace ROOT {
 
namespace Minuit2 {
 
/**
 
 
template wrapped class for adapting to FCNBase signature a IGradFunction
 
@author Lorenzo Moneta
 
@ingroup Minuit
 
*/
 
template <class Function>
class FCNGradAdapter : public FCNGradientBase {
 
public:
   FCNGradAdapter(const Function &f, double up = 1.) : fFunc(f), fUp(up), fGrad(std::vector<double>(fFunc.NDim())) {}
 
   ~FCNGradAdapter() {}
 
   double operator()(const std::vector<double> &v) const override { return fFunc.operator()(&v[0]); }
   double operator()(const double *v) const { return fFunc.operator()(v); }
 
   double Up() const override { return fUp; }
 
   std::vector<double> Gradient(const std::vector<double> &v) const override
   {
      fFunc.Gradient(&v[0], &fGrad[0]);
 
      MnPrint("FCNGradAdapter").Debug([&](std::ostream &os) {
         os << "gradient in FCNAdapter = {";
         for (unsigned int i = 0; i < fGrad.size(); ++i)
            os << fGrad[i] << (i == fGrad.size() - 1 ? '}' : '\t');
      });
      return fGrad;
   }
   std::vector<double> GradientWithPrevResult(const std::vector<double> &v, double *previous_grad, double *previous_g2,
                                              double *previous_gstep) const override
   {
      fFunc.GradientWithPrevResult(&v[0], &fGrad[0], previous_grad, previous_g2, previous_gstep);
 
      MnPrint("FCNGradAdapter").Debug([&](std::ostream &os) {
         os << "gradient in FCNAdapter = {";
         for (unsigned int i = 0; i < fGrad.size(); ++i)
            os << fGrad[i] << (i == fGrad.size() - 1 ? '}' : '\t');
      });
      return fGrad;
   }
   // forward interface
   // virtual double operator()(int npar, double* params,int iflag = 4) const;
   bool CheckGradient() const override { return false; }
 
   GradientParameterSpace gradParameterSpace() const override {
      if (fFunc.returnsInMinuit2ParameterSpace()) {
         return GradientParameterSpace::Internal;
      } else {
         return GradientParameterSpace::External;
      }
   }
 
private:
   const Function &fFunc;
   double fUp;
   mutable std::vector<double> fGrad;
};
 
} // end namespace Minuit2
 
} // end namespace ROOT
 
#endif // ROOT_Minuit2_FCNGradAdapter