I encountered this problem running N03 for 4.8.1p1 on SLC4 compiling geant4 with g++4 -O2 -funsafe-math-optimizations -fno-math-errno -msse3 -mfpmath=sse,387 0x006f929c in G4UrbanMscModel::ComputeGeomPathLength (this=0x9072850) at src/ G4UrbanMscModel.cc:582 582 zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ; (gdb) print tPathLength/currentRange $2 = 1 (gdb) print tPathLength $3 = 0.0095235382324220224 (gdb) print currentRange $4 = 0.0095235382324220224 The problem is solved changing the code as follows diff /afs/cern.ch/sw/geant4/releases/share/geant4.8.1.p01/source/processes/electromagnetic/ standard/src/G4UrbanMscModel.cc ../../../source/processes/electromagnetic/standard/src/ G4UrbanMscModel.cc 582c582,586 < zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ; --- > G4double u = 1.-tPathLength/currentRange; > if (float(u)>0.0) > zmean = (1.-exp(par3*log(u)))/(par1*par3) ; > else > zmean = 1./(par1*par3) ;
more nan Program received signal SIGFPE, Arithmetic exception. 0x00348a1e in G4UrbanMscModel::SampleCosineTheta (this=0x8867020, trueStepLength=0, KineticEnergy=1.4207528465018906) at src/G4UrbanMscModel.cc:763 763 lambdaeff = trueStepLength/currentTau; (gdb) print trueStepLength $1 = 0 (gdb) print currentTau $2 = 0 I protected it with lambdaeff = (trueStepLength>0) ? trueStepLength/currentTau : 0; and at the same place I've also a division by zero in G4UrbanMscModel::SampleCosineTheta (this=0x8655020, trueStepLength=0.015376148707796944, KineticEnergy=0.47799742059990835) at src/G4UrbanMscModel.cc:763 763 lambdaeff = (trueStepLength>0) ? trueStepLength/currentTau : 0; (gdb) print trueStepLength>0 $1 = true (gdb) print trueStepLength $2 = 0.015376148707796944 (gdb) print currentTau $3 = -0 I decided Not to trap them...
THe problem was identified and fixed by author; the results were not effected
*** Problem 962 has been marked as a duplicate of this problem. ***
