Sun wanted the jvm to "replicate exactly" between machines so they chopped off the precision of all intermediate operations to 64 or 32 (double/single) which infuriated kahan
With the NAS Parallel Benchmarks we were trying to encourage as wide a diversity of hardware and algorithms as possible so we were lenient with the acceptable "valid" interval of "correct" behavior. I've already discussed heretical Cray FP. Those were fantastic systems. No way would we disqualify some weird/different algorithm/architecture if it meaningfully advanced the SOA in performance/efficiency. OTOH wars were fought over having any firm accuracy requirements at all. So this jvm thing looked... pointless at best?
This is all nostalgia for a past that actually was. Those were the days my friends.
Spoken like someone who never had to implement multi precision library. Thankfully Sun's idea won, the 80bit shape shifting to 64 bit upon register spill is a distant past, all modern processors implement fully deterministic +-*/ float64 ops, which allows sane and portable libraries for quadfloats, multi precision, interval arithmetic and the like
The 80 bit format was an at-the-time (ATT) engineering optimization that made ATT double precision (DP) more attractive given the better round-off behavior, at "no-cost".
So the interesting question here (that I don't know) is: is "deterministic" quad-precision (QP) as the accuracy upgrade from "non-deterministic" 80bit internal DP, always better economically?
Depends on what the computational problem is, given a budget. And that budget buys things that are only available on the market.
I used to think technology monocultures were a good thing but given the current state of things I have reversed myself. I am happy that life has simplified for you though.
I've been watching, lightly, interval arithmetic for 40 years. As you know algorithm sensitivity information is mandatory. We used intel 80bit FP do evaluate that, slowly, back in the day. We didn't use interval arithmetic, though we knew about it. It wasn't economically viable. Hey C++ what can you do for us? Templates, damn.
How important is interval arithmetic, economically, now?
I spent months in all the corners of P754 and can attest to it being the most carefully thought through and subtly powerful document.
At this time we built custom FPUs for non P754 such as DEC format which iirc was deliberately close to P754 but slightly twisted to maintain code incompatibility.
Anyone who thinks FPU math is deterministic has not got close to circuit design for these beasts. I suppose MAYBE that got fixed in the last 40 years, but the move to GPU leads me to suspect that determinism in all the myriad corner cases is not top of the list.