Hello, this bug occurs in a very particular situation when the Polycone using the plane (Z=0) as an extremity. In that case, the normal at the center of the extrimity is given by the function : G4ThreeVector G4PolyconeSide::Normal( const G4ThreeVector &p, G4double *bestDistance ) { if (p == G4ThreeVector(0.,0.,0.)) { return p; } G4ThreeVector dFrom; G4double dOut2; dFrom = DistanceAway( p, false, dOut2 ); *bestDistance = std::sqrt( dFrom*dFrom + dOut2 ); G4double rad = p.perp(); return G4ThreeVector( rNorm*p.x()/rad, rNorm*p.y()/rad, zNorm ); } with p=(0,0,0) so rad=(0,0,0) and the Vector return is (nan,nan,0). I changed it to if (rad != 0) return G4ThreeVector( rNorm*p.x()/rad, rNorm*p.y()/rad, zNorm ); else return G4ThreeVector( rNorm*p.x()*1000000., rNorm*p.y()*1000000., zNorm ); which gives acceptable results, but you may come up with a better solution. Regards, Pierre
Dear Pierre, Thank you for reporting this problem. For p(0,0,z) rad=p.perp() is equal to zero. In calculation of Normal division by rad is causing nan: return G4ThreeVector( rNorm*p.x()/rad, rNorm*p.y()/rad, zNorm ). But in this case p.x() and p.y() are zeros and Normal can be given by : return G4ThreeVector( 0,0, zNorm ).unit(). Fix will be provided in the next Geant4 release. Best Regards, Tatiana Nikitina
