POSIX 1003.1-2001 contains text about overflow (which might set errno to
ERANGE, or raise an exception). In practice, the result cannot overflow on any
current machine, so this error-handling stuff is just nonsense. (More
precisely, overflow can happen only when the maximum value of the exponent is
smaller than the number of mantissa bits. For the IEEE-754 standard 32-bit and
64-bit floating point numbers the maximum value of the exponent is 128 (resp.
1024), and the number of mantissa bits is 24 (resp. 53).)