@node fenv.h
@section @file{fenv.h}

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/fenv.h.html}

Gnulib module: fenv

Portability problems fixed by Gnulib:
@itemize
@item
This header file is missing on some platforms:
FreeBSD 5.2.1, NetBSD 5.0, OpenBSD 3.8, AIX 5.1, IRIX 6.5, Cygwin 1.7.7, MSVC 9.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
On MSVC, the values of the rounding direction macros have changed:
@c https://github.com/MicrosoftDocs/cpp-docs/issues/4796
In MSVC 14, @code{FE_UPWARD} is 0x100 and @code{FE_DOWNWARD} is 0x200,
whereas in MSVC 14.30, it's the opposite.
@end itemize