Gabriele Cosmo
66 lines
2.9 KiB
C++
66 lines
2.9 KiB
C++
//
|
|
// ********************************************************************
|
|
// * License and Disclaimer *
|
|
// * *
|
|
// * The Geant4 software is copyright of the Copyright Holders of *
|
|
// * the Geant4 Collaboration. It is provided under the terms and *
|
|
// * conditions of the Geant4 Software License, included in the file *
|
|
// * LICENSE and available at http://cern.ch/geant4/license . These *
|
|
// * include a list of copyright holders. *
|
|
// * *
|
|
// * Neither the authors of this software system, nor their employing *
|
|
// * institutes,nor the agencies providing financial support for this *
|
|
// * work make any representation or warranty, express or implied, *
|
|
// * regarding this software system or assume any liability for its *
|
|
// * use. Please see the license in the file LICENSE and URL above *
|
|
// * for the full disclaimer and the limitation of liability. *
|
|
// * *
|
|
// * This code implementation is the result of the scientific and *
|
|
// * technical work of the GEANT4 collaboration. *
|
|
// * By using, copying, modifying or distributing the software (or *
|
|
// * any work based on the software) you agree to acknowledge its *
|
|
// * use in resulting scientific publications, and indicate your *
|
|
// * acceptance of all terms of the Geant4 Software license. *
|
|
// ********************************************************************
|
|
//
|
|
//
|
|
// $Id: G4RandomDirection.hh,v 1.5 2008/03/19 17:00:20 gcosmo Exp $
|
|
// GEANT4 tag $Name: geant4-09-02 $
|
|
//
|
|
//
|
|
// ------------------------------------------------------------
|
|
// GEANT 4 class header file
|
|
// ------------------------------------------------------------
|
|
// Class description:
|
|
//
|
|
// 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
|
|
|
|
#include "globals.hh"
|
|
#include "Randomize.hh"
|
|
#include "G4ThreeVector.hh"
|
|
|
|
inline G4ThreeVector G4RandomDirection()
|
|
{
|
|
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 */
|