TF1Helper.h

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// @(#)root/hist:$Id$
// Author: Lorenzo Moneta 12/06/07

/**********************************************************************
 *                                                                    *
 * Copyright (c) 2007  LCG ROOT Math Team, CERN/PH-SFT                *
 *                                                                    *
 *                                                                    *
 **********************************************************************/

// helper functions used internally by TF1

#ifndef ROOT_TF1Helper
#define ROOT_TF1Helper

#include "TF1.h"

namespace ROOT {

   namespace TF1Helper {

      double IntegralError(TF1 * func, int dim, const double * a, const double * b, const double * params, const double * covmat, double eps);

  /**
     function class representing the derivative with respect a parameter of a given TF1
  */
      class TGradientParFunction {

      public:

         TGradientParFunction(int ipar, TF1 * f)  :
            fPar(ipar),
            fFunc(f)
         {}

         double operator() (double * x, double *) const
         {
            // evaluate gradient vector of functions at point x
            return fFunc->GradientPar(fPar,x);
         }

      private:

         unsigned int fPar;
         mutable TF1 * fFunc;
      };


   } // end namespace TF1Helper

} // end namespace TF1

#endif