G4DNASmoluchowskiDiffusion Class Reference

#include <G4DNASmoluchowskiDiffusion.hh>

Data Structures
struct	BoundingBox

Public Member Functions
double	EstimateCrossingTime (double proba, double distance, double D)
	G4DNASmoluchowskiDiffusion (double epsilon=1e-5)
double	GetInverseProbability (double proba)
double	GetRandomDistance (double _time, double D)
double	GetRandomTime (double distance, double D)
void	InitialiseInverseProbability (double xmax=3e28)
double	Plot (double *x, double *)
double	PlotInverse (double *x, double *)
void	PrepareReverseTable (double xmin, double xmax)
virtual	~G4DNASmoluchowskiDiffusion ()

Static Public Member Functions
static double	ComputeDistance (double sTransform, double D, double t)
static double	ComputeS (double r, double D, double t)
static double	ComputeTime (double sTransform, double D, double r)
static double	GetCumulativeProbability (double sTransform)
static double	GetDensityProbability (double r, double _time, double D)
static double	GetDifferential (double sTransform)

Data Fields
double	fEpsilon
std::vector< double >	fInverse
int	fNbins

Detailed Description

Definition at line 70 of file G4DNASmoluchowskiDiffusion.hh.

Constructor & Destructor Documentation

G4DNASmoluchowskiDiffusion()

G4DNASmoluchowskiDiffusion::G4DNASmoluchowskiDiffusion

(

double

epsilon = 1e-5

)

Definition at line 50 of file G4DNASmoluchowskiDiffusion.cc.

                                                                     :  fEpsilon(epsilon)
{
  fNbins = (int) trunc(1/fEpsilon);
  // std::cout << "fNbins: " << fNbins << std::endl;
#ifdef DNADEV
  assert(fNbins > 0);
#endif
  fInverse.resize(fNbins+2); // trunc sous-estime + borne max a rajouter ==> 2
 
  // std::cout << "fInverse.capacity(): "<< fInverse.capacity() << std::endl;
}

References fEpsilon, fInverse, and fNbins.

~G4DNASmoluchowskiDiffusion()

G4DNASmoluchowskiDiffusion::~G4DNASmoluchowskiDiffusion ( )

virtual

Definition at line 62 of file G4DNASmoluchowskiDiffusion.cc.

{
}

Member Function Documentation

ComputeDistance()

static double G4DNASmoluchowskiDiffusion::ComputeDistance ( double  sTransform, double  D, double  t  )

inlinestatic

Definition at line 82 of file G4DNASmoluchowskiDiffusion.hh.

  {
    return sTransform * 2. * std::sqrt(D * t);
  }

References D().

Referenced by GetRandomDistance().

ComputeS()

static double G4DNASmoluchowskiDiffusion::ComputeS ( double  r, double  D, double  t  )

inlinestatic

Definition at line 76 of file G4DNASmoluchowskiDiffusion.hh.

  {
    double sTransform = r / (2. * std::sqrt(D * t));
    return sTransform;
  }

References D().

ComputeTime()

static double G4DNASmoluchowskiDiffusion::ComputeTime ( double  sTransform, double  D, double  r  )

inlinestatic

Definition at line 87 of file G4DNASmoluchowskiDiffusion.hh.

  {
    return std::pow(r / sTransform, 2.) / (4. * D);
  }

References D().

Referenced by EstimateCrossingTime(), and GetRandomTime().

EstimateCrossingTime()

double G4DNASmoluchowskiDiffusion::EstimateCrossingTime ( double  proba, double  distance, double  D  )

inline

Definition at line 110 of file G4DNASmoluchowskiDiffusion.hh.

  {
    double sTransform = GetInverseProbability(proba);
    return ComputeTime(sTransform, D, distance);
  }

References ComputeTime(), D(), and GetInverseProbability().

GetCumulativeProbability()

static double G4DNASmoluchowskiDiffusion::GetCumulativeProbability ( double  sTransform )

inlinestatic

Definition at line 304 of file G4DNASmoluchowskiDiffusion.hh.

  {
    static double constant = 2./std::sqrt(3.141592653589793);
    return erfc(sTransform) + constant*sTransform*G4Exp(-sTransform*sTransform);
  }

References G4Exp().

Referenced by G4DNASmoluchowskiDiffusion::BoundingBox::BoundingBox(), and PrepareReverseTable().

GetDensityProbability()

static double G4DNASmoluchowskiDiffusion::GetDensityProbability ( double  r, double  _time, double  D  )

inlinestatic

Definition at line 129 of file G4DNASmoluchowskiDiffusion.hh.

  {
    static double my_pi = 3.141592653589793;
    static double constant = 4.*my_pi/std::pow(4.*my_pi, 1.5);
    return r*r/std::pow(D * _time,1.5)*G4Exp(-r*r/(4. * D * _time))*constant;
  }

References D(), and G4Exp().

GetDifferential()

static double G4DNASmoluchowskiDiffusion::GetDifferential ( double  sTransform )

inlinestatic

Definition at line 123 of file G4DNASmoluchowskiDiffusion.hh.

  {
    static double constant = -4./std::sqrt(3.141592653589793);
    return sTransform*sTransform*G4Exp(-sTransform*sTransform)*constant; // -4*sTransform*sTransform*exp(-sTransform*sTransform)/sqrt(3.141592653589793)
  }

References G4Exp().

Referenced by Plot().

GetInverseProbability()

double G4DNASmoluchowskiDiffusion::GetInverseProbability ( double  proba )

inline

Definition at line 310 of file G4DNASmoluchowskiDiffusion.hh.

  {
    size_t index_low = (size_t) trunc(proba/fEpsilon);
    
    if(index_low == 0) // assymptote en 0
    {
      index_low = 1;
      size_t index_up = 2;
      double low_y = fInverse[index_low];
      double up_y = fInverse[index_up];
      double low_x = index_low*fEpsilon;
      double up_x = proba+fEpsilon;
      double tangente = (low_y-up_y)/(low_x - up_x); // ou utiliser GetDifferential(proba) ?
      // double tangente = GetDifferential(proba);
      return low_y + tangente*(proba-low_x);
    }
 
    size_t index_up = index_low+1;
    if(index_low > fInverse.size()) return fInverse.back();
    double low_y = fInverse[index_low];
    double up_y = fInverse[index_up];
 
    double low_x = index_low*fEpsilon;
    double up_x = low_x+fEpsilon;
 
    if(up_x > 1) // P(1) = 0
    {
      up_x = 1;
      up_y = 0; // more general : fInverse.back()
    }
 
    double tangente = (low_y-up_y)/(low_x - up_x);
 
    return low_y + tangente*(proba-low_x);
  }

References fEpsilon, and fInverse.

Referenced by EstimateCrossingTime(), GetRandomDistance(), GetRandomTime(), and PlotInverse().

GetRandomDistance()

double G4DNASmoluchowskiDiffusion::GetRandomDistance ( double  _time, double  D  )

inline

Definition at line 94 of file G4DNASmoluchowskiDiffusion.hh.

  {
    double proba = G4UniformRand();
//    G4cout << "proba = " << proba << G4endl;
    double sTransform = GetInverseProbability(proba);
//    G4cout << "sTransform = " << sTransform << G4endl;
    return ComputeDistance(sTransform, D, _time);
  }

References ComputeDistance(), D(), G4UniformRand, and GetInverseProbability().

GetRandomTime()

double G4DNASmoluchowskiDiffusion::GetRandomTime ( double  distance, double  D  )

inline

Definition at line 103 of file G4DNASmoluchowskiDiffusion.hh.

  {
    double proba = G4UniformRand();
    double sTransform = GetInverseProbability(proba);
    return ComputeTime(sTransform, D, distance);
  }

References ComputeTime(), D(), G4UniformRand, and GetInverseProbability().

InitialiseInverseProbability()

void G4DNASmoluchowskiDiffusion::InitialiseInverseProbability ( double  xmax = 3e28 )

inline

Definition at line 357 of file G4DNASmoluchowskiDiffusion.hh.

  {
    // x > x'
    // P'(x) = p(x') = lim(x->x') (P(x') - P(x))/(x'-x)
    // x'-x = (P(x') - P(x))/p(x')
    // x = x' - (P(x') - P(x))/p(x')
 
    // fInverse initialized in the constructor
 
    assert(fNbins !=0);
    PrepareReverseTable(0,xmax);
  }

References fNbins, and PrepareReverseTable().

Plot()

double G4DNASmoluchowskiDiffusion::Plot ( double *  x, double *    )

inline

Definition at line 351 of file G4DNASmoluchowskiDiffusion.hh.

  {
    return GetDifferential(x[0]);
  }

References GetDifferential().

PlotInverse()

double G4DNASmoluchowskiDiffusion::PlotInverse ( double *  x, double *    )

inline

Definition at line 346 of file G4DNASmoluchowskiDiffusion.hh.

  {
    return GetInverseProbability(x[0]);
  }

References GetInverseProbability().

PrepareReverseTable()

void G4DNASmoluchowskiDiffusion::PrepareReverseTable ( double  xmin, double  xmax  )

inline

Definition at line 263 of file G4DNASmoluchowskiDiffusion.hh.

  {
    double x = xmax;
    int index = 0;
    double nextProba = fEpsilon;
    double proposedX;
 
    BoundingBox boundingBox(xmin, xmax, fEpsilon*1e-5);
 
    while(index <= fNbins)
    // in case GetCumulativeProbability is exact (digitally speaking), replace with:
    // while(index <= fNbins+1)
    {
      nextProba = fEpsilon*index;
 
      double newProba = GetCumulativeProbability(x);
 
      if(boundingBox.Propose(x, newProba, nextProba, proposedX))
      {
        fInverse[index] = x;
        index++;
      }
      else
      {
        if(x == proposedX)
        {
          G4cout << "BREAK : x= " << x << G4endl;
          G4cout << "index= " << index << G4endl;
          G4cout << "nextProba= " << nextProba << G4endl;
          G4cout << "newProba= " << newProba << G4endl;
          abort();
        }
        x = proposedX;
      }
    }
    
    fInverse[fNbins+1] = 0; // P(1) = 0, because we want it exact !
    // Tips to improve the exactness: get an better value of pi, get better approximation of erf and exp, use long double instead of double
//    boundingBox.Print();
  }

References fEpsilon, fInverse, fNbins, G4cout, G4endl, GetCumulativeProbability(), and G4DNASmoluchowskiDiffusion::BoundingBox::Propose().

Referenced by InitialiseInverseProbability().

Field Documentation

fEpsilon

double G4DNASmoluchowskiDiffusion::fEpsilon

Definition at line 372 of file G4DNASmoluchowskiDiffusion.hh.

Referenced by G4DNASmoluchowskiDiffusion(), GetInverseProbability(), and PrepareReverseTable().

fInverse

std::vector<double> G4DNASmoluchowskiDiffusion::fInverse

Definition at line 370 of file G4DNASmoluchowskiDiffusion.hh.

Referenced by G4DNASmoluchowskiDiffusion(), GetInverseProbability(), and PrepareReverseTable().

fNbins

int G4DNASmoluchowskiDiffusion::fNbins

Definition at line 371 of file G4DNASmoluchowskiDiffusion.hh.

Referenced by G4DNASmoluchowskiDiffusion(), InitialiseInverseProbability(), and PrepareReverseTable().

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The documentation for this class was generated from the following files:

• source/processes/electromagnetic/dna/models/include/G4DNASmoluchowskiDiffusion.hh
• source/processes/electromagnetic/dna/models/src/G4DNASmoluchowskiDiffusion.cc