In November 2011, I wrote in <http://lists.gnu.org/archive/html/bug-gnulib/2011-11/msg00069.html>:
glibc 2.11: NaN, fenv bit, errno MacOS X 10.5: NaN, fenv bit math_errhandling (always=MATH_ERREXCEPT) FreeBSD 6.4: NaN, fenv bit math_errhandling (always=MATH_ERREXCEPT) OpenBSD 4.9: NaN NetBSD 5.1: NaN, errno AIX 7.1: NaN, fenv bit, errno math_errhandling (always=MATH_ERRNO) HP-UX 11.31: NaN, fenv bit, errno IRIX 6.5: NaN OSF/1 5.1: 0, errno (<fenv.h> incomplete) Solaris 10: NaN, fenv bit, errno math_errhandling (always=MATH_ERREXCEPT) Cygwin 1.7.9: NaN, errno mingw: NaN, fenv bit, errno MSVC 9: NaN, errno Now I recall that we have a gnulib module 'fpieee', and with this module the table looks like this: glibc 2.11: NaN, fenv bit, errno MacOS X 10.5: NaN, fenv bit math_errhandling (always=MATH_ERREXCEPT) FreeBSD 6.4: NaN, fenv bit math_errhandling (always=MATH_ERREXCEPT) OpenBSD 4.9: NaN NetBSD 5.1: NaN, errno AIX 7.1: NaN, fenv bit, errno math_errhandling (always=MATH_ERRNO) HP-UX 11.31: NaN, fenv bit, errno IRIX 6.5: NaN OSF/1 5.1: NaN, errno (<fenv.h> incomplete) Solaris 10: NaN, fenv bit, errno math_errhandling (always=MATH_ERREXCEPT) Cygwin 1.7.9: NaN, errno mingw: NaN, fenv bit, errno MSVC 9: NaN, errno This means, the most natural way to report exceptional values on all platforms is through a NaN value. This is simpler to achieve than the <fenv.h> replacement. I'm going to write unit tests and support for this convention in the first place. Bruno
