Hi all, the criticism of Kahan is essentially about the replacement of the variety of rounding modes by interval arithmetic, ubox and SORN (decomposition in union of smaller intervals to refine the bounds) as a universal solution. It's not a criticism of the Posit format per se. Implementing a single rounding mode certainly participates in the simplification of the arithmetic unit, but it's not mandatory, it's orthogonal to the representation. Posits have a formal beauty and may reduce the complexity of hardware, power consumption, etc... I like the idea of using short Posits in neural networks. It remains to see if it does not complicate error analysis, because precision is floating (like denormals in IEEE754). Maybe that could be a grief for Kahan too, but that would deserve an update from his side.
Nicolas
Le sam. 12 nov. 2022 à 00:10, Craig Latta craig@blackpagedigital.com a écrit :
Hi Marcel--
Hmm... Patrick just pointed out to me that this critique addresses Unum I. "Posits" are Unum III (Wikipedia link).
Sure, the Wikipedia article is where I noticed the critique. Not
all of its criticisms are addressed by Unum II and III. And it's still interesting, given who wrote it. :) I think posits are lovely, and I've never enjoyed dealing with IEEE 754, but it's not clear to me that the resource-use discussion is closed.
Hmm...
What are you trying to say?
-C
-- Craig Latta :: research computer scientist :: Black Page Digital :: Berkeley, California :: 663137D7940BF5C0AF :: C1349FB2ADA32C4D5314CE ::