SIGFPE, Arithmetic exception with well-defined division

Question

I have the following piece of c++ code:

void update(const int step, const int total) const
{
   double s = static_cast<double>(step);

   double t = static_cast<double>(total);

   std::cout << s/t <<"------\n";

   // etc...
}

I am using the intel c++ compiler with the -fp-trap=all flag activated. When running the code through gdb I get the following error:

Program received signal SIGFPE, Arithmetic exception.
0x000000000040ee07 in NilDa::progressBar::update (this=0x7fffffffbc9c, step=1, total=60000) at /home/d2d/dev/NilDa/sources/utils/progressBar.h:69
69  std::cout << s/t <<"------\n";

I don't really understand what is going on. The division seems to be well defined.

Answer 1

I'm assuming you're using the Intel C++ compiler (I'm not aware of any other compiler having such a flag). If so you can take a look here: https://software.intel.com/content/www/us/en/develop/documentation/cpp-compiler-developer-guide-and-reference/top/compiler-reference/compiler-options/compiler-option-details/floating-point-options/fp-trap-qfp-trap.html#

As stated within that documentation the argument all inherits the trap for inexact results ([no]inexact)

Enables or disables the IEEE trap for inexact result.

Since 1/60000 can not be represented by an floating point number the result is inexact (1.66667e-05).