POSIX specification:
http://www.opengroup.org/onlinepubs/9699919799/basedefs/math.h.html
Gnulib module: math
Portability problems fixed by Gnulib:
int to long double in incorrect on some
platforms:
glibc 2.7 on Linux/SPARC64.
NAN is not defined on some platforms:
OpenBSD 4.0, AIX 5.1, IRIX 6.5, OSF/1 5.1.
NAN is not exposed outside of C99 compilation on some
platforms:
glibc.
NAN and HUGE_VAL expand to a function address
rather than a floating point constant on some platforms:
Solaris 10.
HUGE_VALF and HUGE_VALL are not defined on some
platforms:
glibc/HPPA, glibc/SPARC, AIX 5.1, IRIX 6.5, Solaris 9, MSVC 9.
FP_ILOGB0 and FP_ILOGBNAN are not defined on some
platforms:
NetBSD 5.1, AIX 5.1, IRIX 6.5, Solaris 9, MSVC 9.
Portability problems not fixed by Gnulib:
NAN is not a compile time constant with some compilers:
OSF/1 with Compaq (ex-DEC) C 6.4.
math_errhandling is not defined on some platforms:
glibc 2.11, OpenBSD 4.9, NetBSD 5.1, UP-UX 11, IRIX 6.5, OSF/1 5.1, Cygwin 1.7.9, mingw, MSVC 9.