”This behavior might not be IEEE defined, but even as IEEE undefined (and implementation dependent), it still qualifies those IEEE compliant implementations as

”This behavior might not be IEEE defined, but even as IEEE undefined (and implementation dependent), it still qualifies those IEEE compliant implementations as non-deterministic.” Although IEEE is non-deterministic for other reasons (the transcendental example below is a good illustration) this argument is incorrect. Performing operations on a non-IEEE 80-bit representation and then using a non-IEEE comparison is not a valid argument about non-determinism in IEEE.