FcnAdapter.h

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// @(#)root/mathcore:$Id$
// Author: L. Moneta    10/2005
 
/**********************************************************************
 *                                                                    *
 * Copyright (c) 2005 ROOT Foundation,  CERN/PH-SFT                   *
 *                                                                    *
 **********************************************************************/
 
#ifndef ROOT_Fit_FcnAdapter_H_
#define ROOT_Fit_FcnAdapter_H_
 
#include "Math/IFunction.h"
 
 
//___________________________________________________________
//
// Adapt the interface used in TMinuit (and the TVirtualFitter) for
// passing the objective function in a IFunction  interface
// (ROOT::Math::IMultiGenFunction)
//
 
namespace ROOT {
 
   namespace Fit {
 
class FcnAdapter : public ROOT::Math::IMultiGenFunction {
 
public:
 
   FcnAdapter(void (*fcn)(int&, double*, double&, double*, int ), int dim = 0) :
      fDim(dim),
      fFCN(fcn)
   {}
 
   ~FcnAdapter() override {}
 
    unsigned int NDim() const override { return fDim; }
 
   ROOT::Math::IMultiGenFunction * Clone() const override {
      return new FcnAdapter(fFCN,fDim);
   }
 
   void SetDimension(int dim) { fDim = dim; }
 
private:
 
   double DoEval(const double * x) const override {
      double fval = 0;
      int dim = fDim;
      // call with flag 4
      fFCN(dim, nullptr, fval, const_cast<double *>(x), 4);
      return fval;
   }
 
private:
 
   unsigned int fDim;
   void (*fFCN)(int&, double*, double&, double*, int);
 
};
 
   } // end namespace Fit
 
} // end namespace ROOT
 
#endif //ROOT_Fit_FcnAdapter