G4DNASmoluchowskiDiffusion Class Reference

#include <G4DNASmoluchowskiDiffusion.hh>

Collaboration diagram for G4DNASmoluchowskiDiffusion:

Classes
struct	BoundingBox

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

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

Public Attributes
std::vector< double >	fInverse
int	fNbins
double	fEpsilon

Detailed Description

Definition at line 68 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;
}

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~G4DNASmoluchowskiDiffusion()

G4DNASmoluchowskiDiffusion::~G4DNASmoluchowskiDiffusion ( )

virtual

Definition at line 62 of file G4DNASmoluchowskiDiffusion.cc.

{
}

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Member Function Documentation

ComputeDistance()

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

inlinestatic

Definition at line 80 of file G4DNASmoluchowskiDiffusion.hh.

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

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ComputeS()

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

inlinestatic

Definition at line 74 of file G4DNASmoluchowskiDiffusion.hh.

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

ComputeTime()

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

inlinestatic

Definition at line 85 of file G4DNASmoluchowskiDiffusion.hh.

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

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EstimateCrossingTime()

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

inline

Definition at line 108 of file G4DNASmoluchowskiDiffusion.hh.

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

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GetCumulativeProbability()

static double G4DNASmoluchowskiDiffusion::GetCumulativeProbability ( double  sTransform )

inlinestatic

Definition at line 302 of file G4DNASmoluchowskiDiffusion.hh.

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

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GetDensityProbability()

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

inlinestatic

Definition at line 127 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)*std::exp(-r*r/(4. * D * _time))*constant;
  }

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GetDifferential()

static double G4DNASmoluchowskiDiffusion::GetDifferential ( double  sTransform )

inlinestatic

Definition at line 121 of file G4DNASmoluchowskiDiffusion.hh.

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

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GetInverseProbability()

double G4DNASmoluchowskiDiffusion::GetInverseProbability ( double  proba )

inline

Definition at line 308 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);
  }

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GetRandomDistance()

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

inline

Definition at line 92 of file G4DNASmoluchowskiDiffusion.hh.

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

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GetRandomTime()

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

inline

Definition at line 101 of file G4DNASmoluchowskiDiffusion.hh.

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

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InitialiseInverseProbability()

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

inline

Definition at line 355 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);
  }

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Plot()

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

inline

Definition at line 349 of file G4DNASmoluchowskiDiffusion.hh.

  {
    return GetDifferential(x[0]);
  }

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PlotInverse()

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

inline

Definition at line 344 of file G4DNASmoluchowskiDiffusion.hh.

  {
    return GetInverseProbability(x[0]);
  }

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PrepareReverseTable()

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

inline

Definition at line 261 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();
  }

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Member Data Documentation

fEpsilon

double G4DNASmoluchowskiDiffusion::fEpsilon

Definition at line 370 of file G4DNASmoluchowskiDiffusion.hh.

fInverse

std::vector<double> G4DNASmoluchowskiDiffusion::fInverse

Definition at line 368 of file G4DNASmoluchowskiDiffusion.hh.

fNbins

int G4DNASmoluchowskiDiffusion::fNbins

Definition at line 369 of file G4DNASmoluchowskiDiffusion.hh.

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

• G4DNASmoluchowskiDiffusion.hh
• G4DNASmoluchowskiDiffusion.cc