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// $Id: G4PhysicsFreeVector.hh,v 1.12 2008/09/22 14:49:57 gcosmo Exp $
// GEANT4 tag $Name: geant4-09-02-cand-01 $
//
// 
//--------------------------------------------------------------------
//      GEANT 4 class header file
//
//  G4PhysicsFreeVector.hh
//
//  Class description:
//
//    A physics vector which has values of energy-loss, cross-section, 
//    and other physics values of a particle in matter in a given 
//    range of the energy, momentum, etc. The scale of energy/momentum
//    bins is in free, ie. it is NOT need to be linear or log. Only 
//    restrication is that bin values alway have to increase from
//    a lower bin to a higher bin. This is necessary for the binary
//    search to work correctly.

//  History:
//    02 Dec. 1995, G.Cosmo : Structure created based on object model
//    06 Jun. 1996, K.Amako : Implemented the 1st version
//    01 Jul. 1996, K.Amako : Cache mechanism and hidden bin from the 
//                            user introduced
//    26 Sep. 1996, K.Amako : Constructor with only 'bin size' added
//    11 Nov. 2000, H.Kurashige : Use STL vector for dataVector and binVector
//
//--------------------------------------------------------------------

#ifndef G4PhysicsFreeVector_h
#define G4PhysicsFreeVector_h 1

#include "globals.hh"
#include "G4PhysicsVector.hh"
#include "G4DataVector.hh"

class G4PhysicsFreeVector : public G4PhysicsVector  
{
  public: // with description

    G4PhysicsFreeVector();
    explicit G4PhysicsFreeVector(size_t theNbin);
    G4PhysicsFreeVector(const G4DataVector& binVector, 
                        const G4DataVector& dataVector);
         // Constructors:
         // 'binVector' has the low edge value of each scale bin. 
         // 'dataVector' has the cross-section/energy-loss/etc at 
         // the energy/momenturm of the corresponding a bin of 
         // 'binVector'. 'binVector' and 'dataVector' need to have 
         // the same vector length.
  
    ~G4PhysicsFreeVector();
         // Destructor

    void PutValue( size_t binNumber, G4double binValue, 
                                     G4double dataValue );   
         // To use this method to fill a PhysicsFreeVector, you have
         // to Construct a PhysicsFreeVector of the size you need
         // using G4PhysicsFreeVector(size_t theNbin). Also take
         // note that you have to fill all bin values and data 
         // values before you the PhysicsFreeVector.

  protected:

    size_t FindBinLocation(G4double theEnergy) const;
         // Find bin# in which theEnergy belongs - virtual function
};


inline 
size_t G4PhysicsFreeVector::FindBinLocation(G4double theEnergy) const
{
  // For G4PhysicsFreeVector, FindBinLocation is implemented using
  // the binary search algorithm.
  //
  // Because this is a virtual function, it is accessed through a
  // pointer to the G4PhysicsVector object for most usages. In this
  // case, 'inline' will not be invoked. However, there is a possibility 
  // that the user access to the G4PhysicsFreeVector object directly and 
  // not through pointers or references. In this case, the 'inline' will
  // be invoked. (See R.B.Murray, "C++ Strategies and Tactics", Chap.6.6)

  size_t lowerBound = 0;
  size_t upperBound = numberOfBin-1;

  while (lowerBound <= upperBound)
  {
    size_t midBin = (lowerBound + upperBound)/2;
    if( theEnergy < binVector[midBin] )
       { upperBound = midBin-1; }
    else
       { lowerBound = midBin+1; }
  }

  return upperBound;
}

#endif
