RootFinder.h

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// @(#)root/tmva $Id$
// Author: Andreas Hoecker, Joerg Stelzer, Helge Voss, Kai Voss
 
/**********************************************************************************
 * Project: TMVA - a Root-integrated toolkit for multivariate data analysis       *
 * Package: TMVA                                                                  *
 * Class  : RootFinder                                                            *
 *                                             *
 *                                                                                *
 * Description:                                                                   *
 *      Root finding using Brents algorithm                                       *
 *      (translated from CERNLIB function RZERO)                                  *
 *                                                                                *
 * Authors (alphabetical):                                                        *
 *      Andreas Hoecker <Andreas.Hocker@cern.ch> - CERN, Switzerland              *
 *      Helge Voss      <Helge.Voss@cern.ch>     - MPI-K Heidelberg, Germany      *
 *      Kai Voss        <Kai.Voss@cern.ch>       - U. of Victoria, Canada         *
 *                                                                                *
 * Copyright (c) 2005:                                                            *
 *      CERN, Switzerland                                                         *
 *      U. of Victoria, Canada                                                    *
 *      MPI-K Heidelberg, Germany                                                 *
 *                                                                                *
 * Redistribution and use in source and binary forms, with or without             *
 * modification, are permitted according to the terms listed in LICENSE           *
 * (see tmva/doc/LICENSE)                                          *
 **********************************************************************************/
 
#ifndef ROOT_TMVA_RootFinder
#define ROOT_TMVA_RootFinder
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
// RootFinder                                                           //
//                                                                      //
// Root finding using Brents algorithm                                  //
// (translated from CERNLIB function RZERO)                             //
//                                                                      //
//////////////////////////////////////////////////////////////////////////
 
#include "TObject.h"
 
namespace TMVA {
 
   class MsgLogger;
   class MethodBase;
 
   class RootFinder : public TObject {
 
   public:
 
      RootFinder( MethodBase *method,
                  Double_t rootMin, Double_t rootMax,
                  Int_t    maxIterations = 100,
                  Double_t absTolerance  = 0.0 );
      virtual ~RootFinder( void );
 
      // returns the root of the function
      Double_t Root( Double_t refValue );
 
   private:
 
      Double_t fRootMin;  ///< minimum root value
      Double_t fRootMax;  ///< maximum root value
      Int_t    fMaxIter;  ///< maximum number of iterations
      Double_t fAbsTol;   ///< absolute tolerance deviation
 
      // Methods pointer
      MethodBase *fMethod;
 
      mutable MsgLogger* fLogger;   ///<! message logger
      MsgLogger& Log() const { return *fLogger; }
 
      ClassDef(RootFinder,0); // Root finding using Brents algorithm
   };
 
} // namespace TMVA
 
#endif