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0001 //
0002 // ********************************************************************
0003 // * License and Disclaimer                                           *
0004 // *                                                                  *
0005 // * The  Geant4 software  is  copyright of the Copyright Holders  of *
0006 // * the Geant4 Collaboration.  It is provided  under  the terms  and *
0007 // * conditions of the Geant4 Software License,  included in the file *
0008 // * LICENSE and available at  http://cern.ch/geant4/license .  These *
0009 // * include a list of copyright holders.                             *
0010 // *                                                                  *
0011 // * Neither the authors of this software system, nor their employing *
0012 // * institutes,nor the agencies providing financial support for this *
0013 // * work  make  any representation or  warranty, express or implied, *
0014 // * regarding  this  software system or assume any liability for its *
0015 // * use.  Please see the license in the file  LICENSE  and URL above *
0016 // * for the full disclaimer and the limitation of liability.         *
0017 // *                                                                  *
0018 // * This  code  implementation is the result of  the  scientific and *
0019 // * technical work of the GEANT4 collaboration.                      *
0020 // * By using,  copying,  modifying or  distributing the software (or *
0021 // * any work based  on the software)  you  agree  to acknowledge its *
0022 // * use  in  resulting  scientific  publications,  and indicate your *
0023 // * acceptance of all terms of the Geant4 Software license.          *
0024 // ********************************************************************
0025 //
0026 // Author:  Dennis Wright (SLAC)
0027 // Date:    28 January 2013
0028 //
0029 // Description: implementation base for numerically integrated two-body
0030 //              final state angular distributions in Bertini-style cascade
0031 //
0032 // 20130219 M. Kelsey: Move to .icc file, required for templated classes
0033 // 20130620  Fix Coverity #50295, recursive #include.
0034 // 20130924  M. Kelsey -- Use G4Log, G4Exp for CPU speedup
0035 
0036 #ifndef G4NumIntTwoBodyAngDst_icc
0037 #define G4NumIntTwoBodyAngDst_icc 1
0038 
0039 #include "G4Log.hh"
0040 #include "G4Exp.hh"
0041 #include "Randomize.hh"
0042 
0043 
0044 template <G4int NKEBINS, G4int NANGLES> G4double
0045 G4NumIntTwoBodyAngDst<NKEBINS,NANGLES>::
0046 GetCosTheta(const G4double& ekin, const G4double& pcm) const
0047 {
0048   G4double costh=1.0, slope=1.0;        // Buffers for final result
0049   G4double xrand = G4UniformRand();     // Random value to sample CDF
0050 
0051   if (ekin < labKE[nDists-1]) {
0052     Interpolate(ekin);              // Get intermediate CDF @ energy
0053     for (G4int i=1; i<nAngles; i++) {
0054       if (xrand < angDist[i]) {
0055         slope = (cosBins[i] - cosBins[i-1])/(angDist[i] - angDist[i-1]);
0056         costh = (xrand - angDist[i-1])*slope + cosBins[i-1];
0057         break;
0058       }
0059     }
0060   } else {
0061     slope = 2.*tcoeff*pcm*pcm; 
0062     costh = G4Log(1.0 - xrand*(1. - G4Exp(2.*slope) ) )/slope - 1.0;
0063   }
0064   return costh;
0065 }
0066 
0067 
0068 // Find normalized indefinite integral of angular distribution at interpolated
0069 // kinetic energy
0070 
0071 template <G4int NKEBINS, G4int NANGLES>
0072 void G4NumIntTwoBodyAngDst<NKEBINS,NANGLES>::Interpolate(const G4double& ekin) const
0073 {
0074   for (G4int j=1; j<nDists; j++) {
0075     if (ekin >= labKE[j]) continue; // Find desired pair of cos(theta) CDFs
0076 
0077     G4double frac = (ekin - labKE[j-1])/(labKE[j] - labKE[j-1]);
0078     for (G4int i=0; i < nAngles; i++) {
0079       angDist[i] = (1.0 - frac)*angDists[j-1][i] + frac*angDists[j][i];
0080     }
0081 
0082     break;
0083   }
0084 }
0085 
0086 #endif  /* G4NumIntTwoBodyAngDst_icc */