3 ms·
> floating point math is deterministic. This is news? Isn't this the entire point of the IEEE754 standard, to save us from the days when programs that were we
by derleth 14y ago
> floating point math is deterministic.
This is news? Isn't this the entire point of the IEEE754 standard, to save us from the days when programs that were well-conditioned on a VAX would become numerically unstable on a Cray?
'Cray instability' sounds like a Star Trek episode but it is apparently something that could happen.
http://www.jargon.net/jargonfile/c/crayinstability.html http://www.jargon.net/jargonfile/c/crayinstability.html
- tedunangst 14y agoDepends on compiler options. x86 floating point is 80-bit internally, but 64-bit in memory. Compile the same function with different optimization, for a different CPU, or whatever and get different answers. For gcc, the answer is to use -ffloat-store. But you have to remember to use it.