Floating point error handling: Linux vs OS X

ROOT
1

ROOT Version: 5.34
Platform: Ubuntu 16.04, OS X El Capitan
Compiler: gcc, cling

Hi,

I have two installations of root 5.34, one on Ubuntu 16.04, one on OS X El Capitan. I noticed that when I run
gSystem->GetFPEMask()
I get 7 on Ubuntu and 0 on OS X. That means that without running TSystem::SetFPEMask(), if for example I divide by zero in my program, on Ubuntu it is a fatal error, while on OS X the result is inf and program continues.
Is this difference in default behaviour intended? If yes, why?

Thanks,
Michal

2

ROOT never calls feenableexcept itself - which would mean that we use the defaults. OTOH in a hand-compiled C++ source I see no difference in behavior on Linux and MacOS.

On Macs, ROOT uses SSE2 and its fp exceptions; on Linux it’s using feenableexcept. I’m not sure that this explains a difference in behavior.

3

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