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This commit is contained in:
Gabriele Cosmo
2016-06-09 15:58:43 +02:00
parent 96c8bcd0af
commit b79225fb37
7544 changed files with 245407 additions and 91099 deletions
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source/global/HEPRandom/include/G4RandomDirection.hh
+15 -37
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@@ -24,8 +24,8 @@
// ********************************************************************
//
//
// $Id: G4RandomDirection.hh,v 1.3 2006/06/29 19:00:47 gunter Exp $
// GEANT4 tag $Name: geant4-09-01 $
// $Id: G4RandomDirection.hh,v 1.5 2008/03/19 17:00:20 gcosmo Exp $
// GEANT4 tag $Name: geant4-09-02 $
//
//
// ------------------------------------------------------------
@@ -33,11 +33,16 @@
// ------------------------------------------------------------
// Class description:
//
// Funtion returning a unit 3-vector homogeneously randomised over 4pi
// Function returning a unit 3-vector homogeneously randomised over 4pi
// solid angle. It can be used in any particle scattering methods
// instead of:
// z=R1, x=SQRT(1-R1*R1)*SIN(2*pi*R2), y=SQRT(1-R1*R1)*COS(2*pi*R2)
// providing more performant results.
// History:
// 18.03.08 V. Grichine, unit radius sphere surface based algorithm
// ~ 2007 M. Kossov, algorithm based on 8 Quadrants technique
//
// ------------------------------------------------------------
#ifndef G4RANDOMDIR_HH
#define G4RANDOMDIR_HH
@@ -48,40 +53,13 @@
inline G4ThreeVector G4RandomDirection()
{
// Randomization in one of 8 Quadrants (x>0, y>0, z>0)
//
G4double x=G4UniformRand(), y=G4UniformRand(), z=G4UniformRand();
G4double r2= x*x+y*y+z*z;
while(r2>1.||r2<.000001)
{
x = G4UniformRand(); y = G4UniformRand(); z = G4UniformRand();
r2=x*x+y*y+z*z;
}
G4double r=std::sqrt(r2), quad=G4UniformRand();
if(quad>0.5)
{
if(quad>0.75)
{
if(quad>0.875) return G4ThreeVector(-x/r,-y/r,-z/r);
else return G4ThreeVector(-x/r,-y/r, z/r);
}
else
{
if(quad>0.625) return G4ThreeVector(-x/r, y/r,-z/r);
else return G4ThreeVector(-x/r, y/r, z/r);
}
}
else
{
if(quad>0.25)
{
if(quad>0.375) return G4ThreeVector( x/r,-y/r,-z/r);
else return G4ThreeVector( x/r,-y/r, z/r);
}
else if(quad>0.125) return G4ThreeVector( x/r, y/r,-z/r);
}
return G4ThreeVector( x/r, y/r, z/r);
G4double cosTheta = 2.*G4UniformRand()-1.;
G4double sinTheta2 = 1. - cosTheta*cosTheta;
if( sinTheta2 < 0.) sinTheta2 = 0.;
G4double sinTheta = std::sqrt(sinTheta2);
G4double phi = twopi*G4UniformRand();
return G4ThreeVector(sinTheta*std::cos(phi),
sinTheta*std::sin(phi), cosTheta).unit();
}
#endif /* G4RANDOMDIR_HH */