// @(#)root/minuit2:$Id$
// Author: L. Moneta Wed Oct 18 11:48:00 2006

/**********************************************************************
 *                                                                    *
 * Copyright (c) 2006  LCG ROOT Math Team, CERN/PH-SFT                *
 *                                                                    *
 *                                                                    *
 **********************************************************************/

// Header file for class Minuit2Minimizer

#ifndef ROOT_Minuit2_Minuit2Minimizer
#define ROOT_Minuit2_Minuit2Minimizer

#ifndef ROOT_Math_Minimizer
#include "Math/Minimizer.h"
#endif

#ifndef ROOT_Minuit2_MnUserParameterState
#include "Minuit2/MnUserParameterState.h"
#endif

#ifndef ROOT_Math_IFunctionfwd
#include "Math/IFunctionfwd.h"
#endif

#ifndef ROOT_Math_IParamFunctionfwd
#include "Math/IParamFunctionfwd.h"
#endif





namespace ROOT { 

   namespace Minuit2 { 

      class ModularFunctionMinimizer; 
      class FCNBase; 
      class FunctionMinimum;

      // enumeration specifying the type of Minuit2 minimizers
      enum EMinimizerType { 
         kMigrad, 
         kSimplex, 
         kCombined, 
         kScan,
         kFumili
      };

   }

   namespace Minuit2 { 
//_____________________________________________________________________________________________________
/** 
   Minuit2Minimizer class implementing the ROOT::Math::Minimizer interface for 
   Minuit2 minimization algorithm. 
   In ROOT it can be instantiated using the plug-in manager (plug-in "Minuit2")
   Using a string  (used by the plugin manager) or via an enumeration 
   an one can set all the possible minimization algorithms (Migrad, Simplex, Combined, Scan and Fumili).  
*/ 
class Minuit2Minimizer : public ROOT::Math::Minimizer {

public: 

   /** 
      Default constructor
   */ 
   Minuit2Minimizer (ROOT::Minuit2::EMinimizerType type = ROOT::Minuit2::kMigrad); 

   /** 
      Constructor with a char (used by PM) 
   */ 
   Minuit2Minimizer (const char *  type); 

   /** 
      Destructor (no operations)
   */ 
   virtual ~Minuit2Minimizer (); 

private:
   // usually copying is non trivial, so we make this unaccessible

   /** 
      Copy constructor
   */ 
   Minuit2Minimizer(const Minuit2Minimizer &); 

   /** 
      Assignment operator
   */ 
   Minuit2Minimizer & operator = (const Minuit2Minimizer & rhs); 

public: 

   // clear resources (parameters) for consecutives minimizations
   virtual void Clear();

   /// set the function to minimize
   virtual void SetFunction(const ROOT::Math::Minimizer::IObjFunction & func); 

   /// set gradient the function to minimize
   virtual void SetFunction(const ROOT::Math::Minimizer::IGradObjFunction & func); 

   /// set free variable 
   virtual bool SetVariable(unsigned int ivar, const std::string & name, double val, double step); 

   /// set lower limit variable  (override if minimizer supports them )
   virtual bool SetLowerLimitedVariable(unsigned int  ivar , const std::string & name , double val , double step , double lower );
   /// set upper limit variable (override if minimizer supports them )
   virtual bool SetUpperLimitedVariable(unsigned int ivar , const std::string & name , double val , double step , double upper ); 
   /// set upper/lower limited variable (override if minimizer supports them )
   virtual bool SetLimitedVariable(unsigned int ivar , const std::string & name , double val , double step , double /* lower */, double /* upper */); 
   /// set fixed variable (override if minimizer supports them )
   virtual bool SetFixedVariable(unsigned int /* ivar */, const std::string & /* name */, double /* val */);  

   /// method to perform the minimization
   virtual  bool Minimize(); 

   /// return minimum function value
   virtual double MinValue() const { return fState.Fval(); } 

   /// return expected distance reached from the minimum
   virtual double Edm() const { return fState.Edm(); }

   /// return  pointer to X values at the minimum 
   virtual const double *  X() const { 
      // need to copy them since MnUserParameterState returns them by value
      fValues=fState.Params();
      return &fValues.front(); 
   }

   /// return pointer to gradient values at the minimum 
   virtual const double *  MinGradient() const { return 0; } // not available in Minuit2 

   /// number of function calls to reach the minimum 
   virtual unsigned int NCalls() const { return fState.NFcn(); } 

   /// this is <= Function().NDim() which is the total 
   /// number of variables (free+ constrained ones) 
   virtual unsigned int NDim() const { return fDim; }   

   /// number of free variables (real dimension of the problem) 
   /// this is <= Function().NDim() which is the total 
   virtual unsigned int NFree() const { return fState.VariableParameters(); }  

   /// minimizer provides error and error matrix
   virtual bool ProvidesError() const { return true; } 

   /// return errors at the minimum 
   virtual const double * Errors() const { 
      fErrors = fState.Errors(); 
      return  &fErrors.front(); 
   }

   /** return covariance matrices elements 
       if the variable is fixed the matrix is zero
       The ordering of the variables is the same as in errors
   */ 
   virtual double CovMatrix(unsigned int i, unsigned int j) const;  

   /// minos error for variable i, return false if Minos failed
   virtual bool GetMinosError(unsigned int i, double & errLow, double & errUp); 

   /// return reference to the objective function
   ///virtual const ROOT::Math::IGenFunction & Function() const; 


protected: 
   
   // protected function for accessing the internal Minuit2 object. Needed for derived classes

   virtual const ROOT::Minuit2::ModularFunctionMinimizer * GetMinimizer() const { return fMinimizer; } 

   virtual void SetMinimizer( ROOT::Minuit2::ModularFunctionMinimizer * m)  { fMinimizer = m; } 

   void SetMinimizerType( ROOT::Minuit2::EMinimizerType type);

   virtual const  ROOT::Minuit2::FCNBase * GetFCN() const { return fMinuitFCN; } 

   /// examine the minimum result 
   bool ExamineMinimum(const ROOT::Minuit2::FunctionMinimum & min); 

private: 
   
   // dimension of the function to be minimized 
   unsigned int fDim; 
   // error code
   int fErrorCode; 
   bool fUseFumili; 

   ROOT::Minuit2::MnUserParameterState fState;
   // std::vector<ROOT::Minuit2::MinosError> fMinosErrors;
   ROOT::Minuit2::ModularFunctionMinimizer * fMinimizer;
   ROOT::Minuit2::FCNBase * fMinuitFCN;
   ROOT::Minuit2::FunctionMinimum * fMinimum;
   mutable std::vector<double> fValues;
   mutable std::vector<double> fErrors;

}; 

   } // end namespace Fit

} // end namespace ROOT



#endif /* ROOT_Minuit2_Minuit2Minimizer */