// $Id$
//-----------------------------------------------------------------------
//       The GSI Online Offline Object Oriented (Go4) Project
//         Experiment Data Processing at EE department, GSI
//-----------------------------------------------------------------------
// Copyright (C) 2000- GSI Helmholtzzentrum fuer Schwerionenforschung GmbH
//                     Planckstr. 1, 64291 Darmstadt, Germany
// Contact:            http://go4.gsi.de
//-----------------------------------------------------------------------
// This software can be used under the license agreements as stated
// in Go4License.txt file which is part of the distribution.
//-----------------------------------------------------------------------

#ifndef TGO4FITMODELPOLYNOM_H
#define TGO4FITMODELPOLYNOM_H

#include "TGo4FitModel.h"

class TArrayD;

/**
 * @brief Model objects, which reproduce component of polynomial function.
 *
 * @details Expression can be written like:
 * ~~~
 * Ampl * x^nx * y^ny * z^nz * ...
 * ~~~
 * * The order of polynomial function should be sets up in constructor like:
 * ~~~{cpp}
 *   TGo4FitModelPolynom *p1 = new TGo4FitModelPolynom("Pol1",orderx,ordery,orderz);
 * ~~~
 *   or
 * ~~~{cpp}
 *   TArrayD orders(5);
 *   Orders[0] = 1.; Orders[1] = 0.; ...
 *   TGo4FitModelPolynom *p2 = new TGo4FitModelPolynom("Pol2",Orders);
 * ~~~
 *
 * According to number of parameters in constructor TGo4FitModelPolynom has set of parameters "Order0", "Order1" and so on, representing polynom orders for axis x, y and so on correspondingly.
 * By default, these parameters are fixed and not fitted in optimizations. To change this default behavior, use:
 * ~~~{cpp}
 * p1->FindPar("Order0")->SetFixed(kFALSE);
 * ~~~
 *
 * TGo4FitModelPolynom class always has amplitude parameter, named "Ampl". It can be accessed by its name, for instance:
 * ~~~{cpp}
 * p1->FindPar("Ampl")->SetValue(1000.);
 * ~~~
 * or
 * ~~~{cpp}
 * p1->GetAmplitudePar("Ampl")->SetValue(1000.);
 * ~~~
 *
 * GetAmplitudePar() method can be used in other models classes only if they create amplitude parameters, otherwise method returns 0.
 *
 * @ingroup go4_fit
 */
class TGo4FitModelPolynom : public TGo4FitModel {
   public:

      /**
       * Default constructor.
       */
      TGo4FitModelPolynom();

      /**
       * Creates TGo4FitModelPolynom object with given name for 1-dim case.
       * The order of polynom for x axis can be specified (0 by default).
       */
      TGo4FitModelPolynom(const char *iName, Double_t iOrderX = 0.);

      /**
       * Creates TGo4FitModelPolynom object with given name for 2-dim case.
       * The order of polynom for x and y axes should be specified.
       */
      TGo4FitModelPolynom(const char *iName, Double_t iOrderX, Double_t iOrderY);

      /**
       * Creates TGo4FitModelPolynom object with given name for 3-dim case.
       * The order of polynom for x, y and z axes should be specified.
       */
      TGo4FitModelPolynom(const char *iName, Double_t iOrderX, Double_t iOrderY, Double_t iOrderZ);

      /**
       * Creates TGo4FitModelPolynom object with given name for n-dim case.
       * An array of polynoms orders for appropriate axis should be specified.
       * The size of array will be a dimensions size of polynom. But the n-dim polynom can be used for m-dim case.
       * If n > m, orders for missing axis will be set 0. If n<m, only necessary orders will be used.
       */
      TGo4FitModelPolynom(const char *iName, const TArrayD& iPolynomOrders);

      /**
       * Destroys TGo4FitModelPolynom object.
       */
      virtual ~TGo4FitModelPolynom();

      /**
       * Get polynom order for specified axis.
       */
      Double_t GetPolynomOrder(Int_t naxis);

      /**
       * Returns maximum axis number (dimensions number) in polynom.
       */
      Int_t GetMaxNumAxis();

      /**
       * Sets number of dimensions (maximum axis numbers) in polynom.
       */
      Bool_t SetMaxNumAxis(Int_t numaxis);

      /**
       * Print information on standard output.
       */
      void Print(Option_t *option = "") const override;

      Bool_t BeforeEval(Int_t NDimension) override;
      Double_t EvalN(const Double_t *v) override;
      void AfterEval() override;

   protected:
      TString GetOrderParName(Int_t naxis) const;

   private:
      void CreateOrdersPars(const Double_t *orders, Int_t startaxis, Int_t maxaxis, Int_t AtIndx = -1);

      /**
       * Temporary variable for EvalN() function.
       */
      Int_t Par_ndim{0};                       //!

      /**
       * Temporary variable for EvalN() function.
       */
      TArrayD *fxAllOrders{nullptr};             //!

      /**
       * Temporary variable for EvalN() function.
       */
      Double_t *Par_orders{nullptr};              //!

   ClassDefOverride(TGo4FitModelPolynom,1)
};

#endif // TGO4FITMODELPOLYNOM_H