In practice, I don't think IEEE 754 floating point is deterministic, especially not across multiple ISAs, multiple vendors of the same ISA (Intel, AMD), different generations of the same vendor's cpus, different compilers and different math libraries, even just C's libm.

So just a warning to everyone out there: unless you are very, very careful your floating point code will not be deterministic. If you thought you can just use floats and expect it to "just work" the same, then you're out of luck.

Here's a couple of articles which go into more detail about problems with floating point determinism:

http://gafferongames.com/networking-for-game-programmers/flo...

https://randomascii.wordpress.com/2013/07/16/floating-point-...