G4SmpIsoDir.cc

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// $Id: G4SmpIsoDir.cc 67966 2013-03-13 09:38:38Z gcosmo $
//

#include <cmath>
#include "G4fissionEvent.hh"
#include "G4Pow.hh"
#include "G4PhysicalConstants.hh"

void G4fissionEvent::G4SmpIsoDir(G4double* cosdiru, G4double* cosdirv, G4double* cosdirw) {

/*
  Description
    determine the 3 direction cosines of a particle emitted isotropically
*/

/*
  Input
  Output
            - 3 components of the direction cosines
              (cosdiru, cosdirv, cosdirw)
*/

   G4double cospolang, sinpolang, phi;

/*
   Choose emission angle isotropically.
   Select a polar angle direction cosine.
*/
   G4Pow* Pow=G4Pow::GetInstance();
   cospolang = 1.-2.*fisslibrng();
   sinpolang = std::sqrt(1.-Pow->powA(cospolang, 2.));
/*
   Select an azimuthal angle uniformly on (0,2*pi)
*/
   phi = twopi*fisslibrng();
   *cosdiru = sinpolang * std::cos(phi);
   *cosdirv = sinpolang * std::sin(phi);
   *cosdirw = cospolang;
}