https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98701
--- Comment #11 from Bahram.shahrooz at uc dot edu --- Thanks! This is how I compiled: gfortran FiberAnalysis.f -finit-real=nan -fcheck=all -ffpe-trap=zero,invalid -o FiberAnalysis_v2 This what I get after running (the answers are correct): Program received signal SIGFPE: Floating-point exception - erroneous arithmetic operation. Backtrace for this error: #0 0x105c4ad3d #1 0x105c4a16d #2 0x7fff203c4d7c #3 0x105c34e45 #4 0x105c3c653 #5 0x105c3cae6 zsh: floating point exception /Users/bahram/FiberAnalysis_v2 Saving session... ...copying shared history... ...saving history...truncating history files... ...completed. Deleting expired sessions...none found. Do you've any suggestions for how to trace the source of error so I can fix the code?