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
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
Aha! TY. Sun's floating point people were world class but I still think this was a dumb thing to do.
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.
> this was a dumb thing to do.
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