G4RandomTools.hh File Reference

#include <CLHEP/Units/PhysicalConstants.h>
#include "G4RandomDirection.hh"
#include "G4ThreeVector.hh"
#include "G4TwoVector.hh"
#include "Randomize.hh"
#include "globals.hh"

Go to the source code of this file.

Functions
G4ThreeVector	G4LambertianRand (const G4ThreeVector &normal)
G4ThreeVector	G4PlaneVectorRand (const G4ThreeVector &normal)
G4TwoVector	G4RandomPointInEllipse (G4double a, G4double b)
G4TwoVector	G4RandomPointOnEllipse (G4double a, G4double b)
G4ThreeVector	G4RandomPointOnEllipsoid (G4double a, G4double b, G4double c)
G4double	G4RandomRadiusInRing (G4double rmin, G4double rmax)

Function Documentation

G4LambertianRand()

G4ThreeVector G4LambertianRand ( const G4ThreeVector &  normal )

inline

Definition at line 58 of file G4RandomTools.hh.

{
  G4ThreeVector vect;
  G4double ndotv;
  G4int count            = 0;
  const G4int max_trials = 1024;
 
  do
  {
    ++count;
    vect  = G4RandomDirection();
    ndotv = normal * vect;
 
    if(ndotv < 0.0)
    {
      vect  = -vect;
      ndotv = -ndotv;
    }
 
  } while(!(G4UniformRand() < ndotv) && (count < max_trials));
 
  return vect;
}

References G4RandomDirection(), G4UniformRand, and CLHEP::normal().

Referenced by G4OpBoundaryProcess::DoReflection().

G4PlaneVectorRand()

G4ThreeVector G4PlaneVectorRand ( const G4ThreeVector &  normal )

inline

Definition at line 85 of file G4RandomTools.hh.

{
  G4ThreeVector vec1 = normal.orthogonal();
  G4ThreeVector vec2 = vec1.cross(normal);
 
  G4double phi    = CLHEP::twopi * G4UniformRand();
  G4double cosphi = std::cos(phi);
  G4double sinphi = std::sin(phi);
 
  return cosphi * vec1 + sinphi * vec2;
}

References CLHEP::Hep3Vector::cross(), G4UniformRand, CLHEP::normal(), and CLHEP::twopi.

G4RandomPointInEllipse()

G4TwoVector G4RandomPointInEllipse ( G4double  a, G4double  b  )

inline

Definition at line 115 of file G4RandomTools.hh.

{
  G4double aa = (a * a == 0) ? 0 : 1 / (a * a);
  G4double bb = (b * b == 0) ? 0 : 1 / (b * b);
  for(G4int i = 0; i < 1000; ++i)
  {
    G4double x = a * (2 * G4UniformRand() - 1);
    G4double y = b * (2 * G4UniformRand() - 1);
    if(x * x * aa + y * y * bb <= 1)
      return G4TwoVector(x, y);
  }
  return G4TwoVector(0, 0);
}

References G4UniformRand.

Referenced by G4Ellipsoid::GetPointOnSurface(), G4EllipticalCone::GetPointOnSurface(), and G4EllipticalTube::GetPointOnSurface().

G4RandomPointOnEllipse()

G4TwoVector G4RandomPointOnEllipse ( G4double  a, G4double  b  )

inline

Definition at line 133 of file G4RandomTools.hh.

{
  G4double A      = std::abs(a);
  G4double B      = std::abs(b);
  G4double mu_max = std::max(A, B);
 
  G4double x, y;
  for(G4int i = 0; i < 1000; ++i)
  {
    G4double phi = CLHEP::twopi * G4UniformRand();
    x            = std::cos(phi);
    y            = std::sin(phi);
    G4double mu  = std::sqrt((B * x) * (B * x) + (A * y) * (A * y));
    if(mu_max * G4UniformRand() <= mu)
      break;
  }
  return G4TwoVector(A * x, B * y);
}

References A, B(), G4UniformRand, G4INCL::Math::max(), and CLHEP::twopi.

Referenced by G4EllipticalTube::GetPointOnSurface().

G4RandomPointOnEllipsoid()

G4ThreeVector G4RandomPointOnEllipsoid ( G4double  a, G4double  b, G4double  c  )

inline

Definition at line 156 of file G4RandomTools.hh.

{
  G4double A      = std::abs(a);
  G4double B      = std::abs(b);
  G4double C      = std::abs(c);
  G4double mu_max = std::max(std::max(A * B, A * C), B * C);
 
  G4ThreeVector p;
  for(G4int i = 0; i < 1000; ++i)
  {
    p            = G4RandomDirection();
    G4double xbc = p.x() * B * C;
    G4double yac = p.y() * A * C;
    G4double zab = p.z() * A * B;
    G4double mu  = std::sqrt(xbc * xbc + yac * yac + zab * zab);
    if(mu_max * G4UniformRand() <= mu)
      break;
  }
  return G4ThreeVector(A * p.x(), B * p.y(), C * p.z());
}

References A, B(), C(), G4RandomDirection(), G4UniformRand, G4INCL::Math::max(), CLHEP::Hep3Vector::x(), CLHEP::Hep3Vector::y(), and CLHEP::Hep3Vector::z().

G4RandomRadiusInRing()

G4double G4RandomRadiusInRing ( G4double  rmin, G4double  rmax  )

inline

Definition at line 100 of file G4RandomTools.hh.

{
  if(rmin == rmax)
  {
    return rmin;
  }
  G4double k = G4UniformRand();
  return (rmin <= 0) ? rmax * std::sqrt(k)
                     : std::sqrt(k * rmax * rmax + (1. - k) * rmin * rmin);
}

References G4UniformRand.

Referenced by G4EllipticalCone::GetPointOnSurface().